DOF Subsea DOM-A-Rev 0 Air & Emerg Proc

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DOF SUBSEA

DIVING OPERATIONS MANUAL

ANNEXE A

AIR DIVING OPERATIONS AND

EMERGENCY PROCEDURES

DOF Subsea Pty Ltd

Level 1, 181 St Georges Terrace

Perth, WA 6000, Australia

Date Rev Description Prepared Checked Approved

14/08/07 A Issued for revision K.Sinclair J.Rossier

10/12/07 B Issued for Review K.Sinclair J.Rossier

14/01/08 0 Issued for Use K.Sinclair J.Rossier S.Brown

Diving Operations Manual – Annexe A Air Diving Operations and Emergency Procedures

Document No: CS-DV-MN-001 Annexe A 2 Rev 0

TABLE OF CONTENTS

1.0 DIVING OPERATIONS ..........................................................................................................5 1.1 STANDARD OPERATIONAL PROCEDURES....................................................................................................5 1.1.1 Site ........................................................................................................................................................................5 1.1.2 Access To The Job Site .....................................................................................................................................5 1.1.3 Dive Tables ..........................................................................................................................................................5 1.2 MOBILISATION - REQUIREMENTS ................................................................................................................6 1.2.1 Safety Meeting Vessel Induction ......................................................................................................................6 1.2.2 Dive Spread Setup ..............................................................................................................................................6 1.2.3 Time Keeping And Recording ...........................................................................................................................6 1.2.4 Air and Oxygen Requirements ..........................................................................................................................7 1.2.5 Purity of Air...........................................................................................................................................................8 1.2.6 Bail-out Bottle.......................................................................................................................................................8 1.2.7 Air Quads..............................................................................................................................................................8 1.2.8 Stage Onboard Air Supply .................................................................................................................................8 1.2.9 Diving Breathing Hose........................................................................................................................................8 1.3 DECK DECOMPRESSION CHAMBERS ..........................................................................................................9 1.3.1 Pre-Decompression Checks..............................................................................................................................9 1.3.2 Deck Decompression Chamber (DDC) Operation .......................................................................................10 1.3.3 Air Sample Procedures ....................................................................................................................................11 1.3.4 Equipment/Machinery Container ....................................................................................................................11 1.3.5 Compressors......................................................................................................................................................12 1.3.6 Video System.....................................................................................................................................................12 1.3.7 Launch and Recovery System ........................................................................................................................12 1.3.8 Cutting Equipment.............................................................................................................................................13 1.3.9 Communications................................................................................................................................................13 1.3.10 Diving Equipment General...........................................................................................................................13 1.4 DIVE TASK BRIEFINGS.............................................................................................................................15 1.4.1 Operator Briefings .............................................................................................................................................15 1.4.2 Vessel Master / PIC Briefings..........................................................................................................................15 1.5 EMERGENCY DRILLS ...............................................................................................................................17 1.5.1 Daily Checks ......................................................................................................................................................17 1.6 PRE-DIVE CHECKS .................................................................................................................................19 1.6.1 Dive Control Panel Prompt Lists .....................................................................................................................21 1.6.2 Diver’s Equipment Prompt List ........................................................................................................................22 1.6.3 LP Air Compressor Prompt List.......................................................................................................................23 1.6.4 DDC Prompt List ...............................................................................................................................................24 1.6.5 LARS Prompt List..............................................................................................................................................25 1.6.6 Dress ...................................................................................................................................................................26 1.7 LIFELINE SIGNALS (AS PER AS2299.1: 2007) ..........................................................................................27 1.7.1 Types of Signals ................................................................................................................................................27 1.7.2 Attendant to Diver .............................................................................................................................................28 1.7.3 Diver to Attendant .............................................................................................................................................28 1.7.4 Hand Signals......................................................................................................................................................29 1.8 DEMOBILISATION.....................................................................................................................................30 1.8.1 Demobilisation checklist ...................................................................................................................................31 2.0 DIVING PROCEDURES – US NAVY DECOMPRESSION TABLES................................... 32 2.1 US NAVY DECOMPRESSION TABLES ........................................................................................................32 2.1.2 Air Decompression Definitions ........................................................................................................................33 2.1.3 Accumulative Dives...........................................................................................................................................35



2.2 TABLE SELECTION...................................................................................................................................36 2.2.1 Selection of Decompression Schedule ..........................................................................................................36 2.2.2 Ascent Procedures............................................................................................................................................38 2.2.3 Diving At High Altitudes....................................................................................................................................39 2.2.4 Unlimited / No-Decompression Limits and Repetitive Group Designation Table for No-Decompression Air Dives..............................................................................................................................................40 2.3 US NAVY STANDARD AIR DECOMPRESSION TABLE...................................................................................43 2.3.1 Table — US Navy Standard Air Decompression Table ..............................................................................43 2.4 SURFACE DECOMPRESSION TABLE USING OXYGEN..................................................................................54 2.4.1 Procedure ...........................................................................................................................................................54 2.4.2 Oxygen System Failure (40-FSW Chamber Stop).......................................................................................55 2.4.3 CNS Oxygen Toxicity (40-FSW Chamber Stop). .........................................................................................56 2.4.4 Convulsions at the 40-FSW Chamber Stop. .................................................................................................57 2.4.5 Repetitive Dives. ...............................................................................................................................................57 2.4.6 Table – Surface Decompression Using Oxygen ..........................................................................................58 2.5 SURFACE DECOMPRESSION USING AIR....................................................................................................63 2.5.1 Table – Surface Decompression Using Air ...................................................................................................64 2.6 OMITTED DECOMPRESSION .....................................................................................................................73 2.6.1 Planned and Unplanned Omitted Decompression .......................................................................................73 2.6.2 Table – Management of Asymptomatic Decompression.............................................................................74 2.6.3 Omitted Decompression Procedures .............................................................................................................75 2.6.4 USN Table 5.......................................................................................................................................................77 2.6.5 USN Table 6.......................................................................................................................................................79 3.0 DIVING PROCEDURES – DCIEM DECOMPRESSION TABLES ....................................... 81 3.1 INTRODUCTION........................................................................................................................................81 3.1.2 Use Of Tables ....................................................................................................................................................81 3.1.3 Definitions...........................................................................................................................................................81 3.2 STANDARD AIR DECOMPRESSION (DECOMPRESSION IN THE WATER) ........................................................84 3.2.1 Procedure ...........................................................................................................................................................84 3.2.2 Standard Air Decompression Table (Metres) ...............................................................................................85 3.3 SURFACE DECOMPRESSION WITH OXYGEN (SUR D O2 ) ..........................................................................94 3.3.1 Procedure ...........................................................................................................................................................94 3.3.2 Oxygen related problems during Sur D O2....................................................................................................96 3.3.3 Surface Decompression Using Oxygen.........................................................................................................98 3.4 REPETITIVE DIVING ...............................................................................................................................108 3.4.1 Repetitive Factors (RF) For Surface Intervals (SI) For Repetitive Diving...............................................108 3.4.2 No-decompression Limits For Repetitive Diving ........................................................................................108 3.4.3 Repetitive Dives Not Requiring Decompression ........................................................................................109 3.4.4 Repetitive Dives Requiring Decompression................................................................................................111 3.4.5 Surface Intervals Less Than 15 Min.............................................................................................................112 3.4.6 Adjustments For Multiple Repetitive Dives..................................................................................................113 3.4.7 Flying after diving ............................................................................................................................................114 3.4.8 Table - Repetitive Factors (RF) For Surface Intervals (SI) For Repetitive Diving .................................115 3.4.9 Table - No-Decompression Limits For Repetitive Diving ..........................................................................116 3.5 OMITTED DECOMPRESSION ...................................................................................................................117 3.5.1 Compression Chamber Immediately Available (Less Than 7 Min) .........................................................118 3.5.2 Compression Chamber Not Immediately Available ...................................................................................119 3.5.3 Violation of 7 minute surface interval — Sur D O2 .....................................................................................120 3.5.4 Decompression Stress During Surface Interval—Sur D O2......................................................................120 3.5.5 DCIEM - Omitted Decompression Flow Chart ............................................................................................121 3.6 DEPTH CORRECTIONS FOR DIVING AT ALTITUDE....................................................................................122 3.6.1 Procedure .........................................................................................................................................................122 3.6.2 Table - Depth Corrections—Diving At Altitude (Metres)............................................................................124 4.0 EMERGENCIES - DIVING..................................................................................................125 4.1 PERSONNEL CASUALTY PROCEDURES ...................................................................................................126 4.2 RESUSCITATION....................................................................................................................................127



4.2.1 Expired Air Resuscitation (EAR) ...................................................................................................................127 4.2.2 Cardiac Resuscitation.....................................................................................................................................127 4.3 BLEEDING AND SHOCK ..........................................................................................................................128 4.3.1 Controlling Massive Bleeding ........................................................................................................................128 4.3.2 Shock ................................................................................................................................................................128 4.4 TEMPERATURE RELATED INJURY ...........................................................................................................129 4.4.1 Hypothermia.....................................................................................................................................................129 4.4.2 Heat Stroke ......................................................................................................................................................130 4.4.3 Treatment for Heat Exhaustion (Hyperthermia)..........................................................................................130 4.5 MARINE ANIMAL INJURIES......................................................................................................................131 4.5.1 Bites ..................................................................................................................................................................131 4.5.2 Puncture Wounds............................................................................................................................................134 4.5.3 Stings ................................................................................................................................................................134 4.5.4 Electric Shocks ................................................................................................................................................136 4.5.5 Marine Animal Injuries in Remote Areas .....................................................................................................136 4.6 GAS POISONINGS AND OTHER RELATED PROBLEMS ...............................................................................137 4.6.1 Respiratory Emergencies...............................................................................................................................138 4.6.2 Oxygen Deficiency ..........................................................................................................................................139 4.6.3 Nitrogen Narcosis............................................................................................................................................139 4.6.4 Oxygen Toxicity ...............................................................................................................................................141 4.6.5 Drowning ..........................................................................................................................................................143 4.7 BAROTRAUMAS .....................................................................................................................................144 4.7.1 Squeeze............................................................................................................................................................144 4.7.2 Gas Expansion and Reverse Squeeze........................................................................................................145 4.7.3 Round Or Oval Window Rupture ..................................................................................................................145 4.8 MEDICAL EMERGENCIES REQUIRING RECOMPRESSION...........................................................................146 4.8.1 Diagnosis..........................................................................................................................................................146 4.8.2 First Aid.............................................................................................................................................................148 4.8.3 Recompression Therapy ................................................................................................................................149 4.8.4 Recompression Treatment ............................................................................................................................150 4.8.5 No Recompression Chamber ........................................................................................................................150 4.8.6 Decompression & Recompression Treatment ............................................................................................151 5.0 NON-PRESSURE RELATED DIVING EMERGENCIES.................................................... 152 5.1 FIRE EMERGENCIES ..............................................................................................................................152 5.1.1 General Fires ...................................................................................................................................................152 5.1.2 Smoke / Fumes / Gas Procedure .................................................................................................................152 5.1.3 Chamber Fire - General .................................................................................................................................154 5.2 LOSS OF AIR / GAS PROCEDURE............................................................................................................156 5.3 LOST COMMUNICATIONS PROCEDURE....................................................................................................158 5.4 LAUNCH AND RECOVERY SYSTEM FAILURE PROCEDURE.........................................................................160 5.5 ENTANGLED DIVER PROCEDURE............................................................................................................161 5.6 INJURED / UNCONSCIOUS DIVER PROCEDURE ........................................................................................162 5.7 FIELD HAZARDS / INCIDENTS PROCEDURE..............................................................................................164 5.8 DANGER RESPONSE AIRWAY BREATHING CIRCULATION FLOW CHART.....................................................165



1.0 DIVING OPERATIONS

1.1 STANDARD OPERATIONAL PROCEDURES

1.1.1 Site

The dive site, which may be on land, a jetty, a platform or vessel that is at anchor, fixed to an installation or in DP mode, must provide the following facilities before diving operations may take place.

• Safe and suitable for the purpose of setting up a dive control station.

• Large enough for the dive equipment to be set up, maintained and securely stowed.

• Provide safe and suitable access to, and exit from the water, for both working divers or standby diver in an emergency.

1.1.2 Access To The Job Site

The distance from the diving platform to the water will determine how the diver will enter and exit and for distances of up to three metres, a diving ladder may be utilised. For distances beyond three metres, for example, from a jack up rig, a diver's stage (which must comply with the DOF Subsea DOM section 7.4.7.2) shall be used.

Whenever a diver is deployed, a down line to the job site shall be used. The down line must be at least 12 mm diameter for a diver, or 18 mm diameter for a stage, and shall be secured to the job site with a shackle and an eye on the rope end. It should be secured by means of a weak link.

If diving is taking place from a fixed platform and a stage is utilised, a tugger wire, if available, is the preferred option for down line purposes.

A dive ladder must be of sufficient size and build to support a fully dressed diver whilst allowing the diver to descend or ascend with or without fins.

It must also be able to be secured in such a fashion to the dive platform that it will not move excessively due to the swell or motion of a vessel or through use by the diver.

1.1.3 Dive Tables

Unless directed otherwise by the Operations Manager, the dive tables used on all DOF Subsea air diving work sites will be current US Navy Air Standard Diving Tables with the exception of surface decompression where USN (Modified) Tables will be used. Refer to the Tables in section 2.0 of this Annexe.



1.2 MOBILISATION - REQUIREMENTS

1.2.1 Safety Meeting Vessel Induction

Prior to setting up and function testing the dive system, the diving crew must be inducted onto the worksite, whether it be a barge, vessel, platform, wharf etc.

Apart from safety and procedures relevant to the site, the Diving Supervisor must discuss general diving procedures and safety relating to diving with the Site Safety Officer and PIC. All relevant legislation shall also be highlighted.

The diving system will not be set up until these matters are finalised.

1.2.2 Dive Spread Setup

Once mobilised onto a diving platform, the following must be adhered to:

• System set up and function tested.

• System sea fastened, if required.

• Safety railing installed, if required.

• Appropriate operational tags installed. In particular, "Do Not Touch" signs for divers' electrical compressor power outlet switch.

• System Function Testing

1.2.3 Time Keeping And Recording

All DOF Subsea dives will be conducted on an elapsed time basis, using a stop watch in conjunction with real time notation.

Divers' times, tasks, decompression, etc., will be recorded in the following:

• DOF Subsea Dive Log Book;

• DOF Subsea Daily / Narrative Job Log Book;

• DOF Subsea Supervisor Deck / Narrative Log Book; and will include all incidents and occurrences pertaining to the dive.

Note: For diving conducted under the jurisdiction of the P(SL)Diving Safety Regulations 2002, an audio tape will be used to record the dive. If no incidents occur during the dive day, the tapes may be reused on the following day.

All divers are to record their own personal dives on a daily basis in personnel dive log books whilst paying attention to the detail required in logging of dives as per DOF Subsea DOM, AS/NZS2299.1: 2007 and the P(SL)(Diving Safety) Regulations 2002.



Supervisor and diver log books, Australian certification, current medical qualifications, current divers medical and (T)BOSIET certification, must be carried by all members of the dive team on all DOF Subsea jobs.

1.2.4 Air and Oxygen Requirements

For all dives, two independent air supplies shall be available. These supplies can be either:

Supply Type

1 • Primary supply – LP compressor, and

• Reserve supply – HP air

2 • Primary supply – LP compressor, and

• Reserve supply – LP compressor

NOTE: If LP compressors are used as primary and secondary air supply they shall have independent power sources or back up power sources.

3 • Primary supply – HP air, and

• Reserve supply – HP air,

The supply source must be capable of delivering a minimum volume per diver of 42.5 litres/min/depth bar absolute, to a maximum depth of 50 msw (165 fsw).

Air supplies to the deck decompression chambers should be arranged in such a manner that pressurisation or ventilation of the chamber does not deprive the working diver of his supply

The following minimum quantities of air and oxygen must be available on site;

• Sufficient compressed air to perform a planned dive of normal duration to a chosen depth.

• Additional reserves of air for two emergency dives to the same depth.

• Air to pressurise the DDC to a maximum treatment depth of 50 msw and complete a full US Navy Treatment Table 6A with necessary ventilations.

• Oxygen for three complete surface decompressions.

• Reserves of oxygen for two divers on an extended US Navy Treatment Table 6.



1.2.5 Purity of Air

Supervisors must ensure that careful attention is paid to the sighting of compressor inlets to prevent dangerous gases being drawn into the compressor inlet.

On worksites where only air diving is taking place it may be necessary for the Supervisor to increase the frequency of air purity testing. Neither of these requirements however, negate the need for air from all worksites to comply with the specifications detailed within section 7.4.1 of the DOF Subsea DOM.

1.2.6 Bail-out Bottle

See Section 7.4.2 of the DOF Subsea DOM for details of bailout requirements for air diving operations.

1.2.7 Air Quads

All air quads to be analysed for O² content. Quads which are not filled with an HP compressor must be changed out at least once every 24 months.

• Check quad air analysis certificate is in date.

• All valves actioned at least weekly during a period of non use.

Minimum four bottles opened on HP air supply, pressures noted and regulator set to a minimum of 180 PSI. Regulator to be backed off at nights if not in use and whips bled down.

1.2.8 Stage Onboard Air Supply

Where a stage is used it will be fitted with onboard air reserve to support a diver at the maximum working depth for a period of not less than 10 minutes. This will normally be by provision of 1 “G” size bottle.

1.2.9 Diving Breathing Hose

A diver’s umbilical shall:

• Have a minimum internal diameter of 8mm.



1.3 DECK DECOMPRESSION CHAMBERS

Refer to the DOF Subsea DOM, Section 7.3 on the operational procedural requirements of the DDC before commencing any diving in which a DDC is used on the dive site.

The following procedures will be strictly adhered to with the use of DOF Subsea Deck Decompression Chambers.

1.3.1 Pre-Decompression Checks

1 Blow down valves, open on the inside, closed on the outside

2 Exhaust valves, open on the inside, closed on the outside

3 Equalisation valve, open on the inner lock, closed in the outer lock

4 Gas sample, open on the inside, closed on the outside

5 Medical lock, closed internally and externally

6 Pneumos open internally and externally. Crossovers closed on the outside panel

7 Chamber relief valves, open both internally and externally

8 Drain valves, closed externally. No valve required on the inside but a plug with a suitable cover should be kept in an accessible position, ready for use

9 Oxygen and overboard dumps closed on the outside and inside. Oxygen open at source, HP supply and LP supply pressures recorded.

10 LP supply valve open, HP supply valve closed on panel. Both open at source. HP supply and LP supply pressures recorded

Once the system has been function tested, the inner lock will be pressurised to a sufficient pressure to take the outer lock to a depth of 50 feet without assistance from HP or LP sources. For all DOF Subsea chambers, 75 feet in the inner lock is sufficient to achieve this.



1.3.2 Deck Decompression Chamber (DDC) Operation

The outer lock door will remain open when not in use.

Once it is known that surface decompression is to be undertaken, the chamber operator, in addition to conducting the pre-decompression check, will place in the outer lock items required by the diver during decompression. (These may consist of a towel, items of clothing, a drink and reading material, etc.)

If not told by the Diving Supervisor, the chamber operator will find out the decompression schedule to be used and enter it on the chamber dive log.

The diver, once entering the chamber, will use the equalisation valve at the same time as the chamber operator pressurizes the outer lock by actioning the blow down valve.

A tender on the outside will hold the door closed until a seal has been made. The diver inside the outer lock may have to assist by leaning on the door. A “strong back” shall be available if required.

Immediately, once a seal has been made, the diver will go onto oxygen. This will necessitate both internal and external oxygen and overboard dump valves being open. Time spent on oxygen in the outer lock does not count as decompression time but is mandatory.

As communication is difficult due to noise on blow down, the diver must indicate at the port that he is in a satisfactory condition. If he is experiencing difficulty with the pressurisation, he must immediately ask for it to be stopped until the problem is rectified.

Once the chamber has equalised, the equalisation valve in the outer lock will be closed, oxygen and overboard dumps internally and externally closed, blow down stopped and the diver transferred to the inner lock. Immediately before any other action, he will go onto oxygen by opening both the oxygen supply and overboard dump valve and donning a bib.

Only once the diver has transferred through and is preparing to don his bib, are the external, inner lock, oxygen and overboard dump valves to be opened.

Once the diver is on oxygen, the outer lock is taken away in the following manner:

• The diver will close the door and lean on it to assist gaining a seal.

• The chamber operator will open the outer lock exhaust whilst simultaneously opening the inner lock blow down to accelerate a pressure differential. Once a seal has been made, the blow down is closed and the exhaust of the entry lock continued until it is on the surface. Remember, the entry lock must be kept on the surface when not in use.

NOTE: It is of particular importance that the pressurisation of the inner lock, whilst depressurising the outer lock to force a seal, does not exceed 1-2 FSW.

• Once the seal has been made, ensure the inner lock is brought back to 50 feet or the depth required by the tables being used.



During the decompression, continually monitor the diver to determine he is not suffering any undue effects from the surface decompression.

Monitor the oxygen content of the chamber regularly and, at least once in every twenty minutes, flush the chamber by operating the exhaust and blow down valve simultaneously for five minutes. Maintain pressure as close as possible to the required depth.

Record the times and any unusual incident in the chamber log and report them to the Diving Supervisor.

Follow the USN (Modified) Tables or other designated tables religiously during the decompression.

NOTE: DCIEM Table Surface Decompression procedures vary significantly from listed here.

On ascent, DOF Subsea policy is for a ten minute bleed from 40 FSW to the surface. Always check on the diver prior to ascent, to ascertain his condition and advise him that ascent is due to start.

Control the rate of ascent by the use of the exhaust valve to maintain a rate of ascent of four feet per minute.

Once the diver has reached the surface, the chamber operator will check that he is physically fit and record the result on the dive log.

The operator will then close the oxygen and overboard dump valves on the outside, purge the oxygen internally and close both internal oxygen and overboard dump valves. Once purged, clean the bib used with a DOF Subsea approved disinfectant. Under no circumstances are oxygen and overboard dump valves, except for oxygen at source, to be left open when not in use.

Conduct pre-decompression check before pressurising the inner lock back to 75 FSW.

For cleaning, refer to the Maintenance Log Book for the individual DDC.

1.3.3 Air Sample Procedures

When taking an air sample for analysis refer to DOF Subsea DOM E- Section 1.4.2.

1.3.4 Equipment/Machinery Container

Ensure ship's electrician is informed of power supply requirements and checks the integrity of all power supplies before use. Do not plug into any electrical outlet before informing the Diving Supervisor.



1.3.5 Compressors

Site compressor so that only clean air is taken into the air intake.

Carry out daily checks as per compressor maintenance log book.

Display warning of compressor operation.

Ensure the delivery hose cannot be damaged and is unlikely to be caught by any moving object, ie., crane hook, winch wire, hot areas, eg: exhaust, etc.

1.3.6 Video System

Set up and run video system.

1.3.7 Launch and Recovery System

Ensure platform is securely fastened to the deck before use. Chains may be substituted for welding, provided they are certified and attached to certified tie down points. Welds may be subjected to NDT.

Set up and run LARS.

Check for an alternate means of recovering diver or dive stage. This may include the following:

• Crane.

• Tugger.

• Cargo slings.

• Standby vessel.

• Ship’s rescue boat.

• Ladder.

• Alternate power supply for LARS winch.

Ensure alternate diver recovery system or method explained at dive site induction.

Man riding winches shall incorporate two independent brake operating mechanisms, at least one of which should be applied automatically.

The wire rope and all attachments shall be certified as having a breaking load of at least weight (8) times the SWL.



Where a stage is used it shall:

• Be large enough to accommodate a minimum of two persons with all their equipment, in uncramped conditions.

• Be prevented from tipping or spinning.

• Have internal hand grips.

• Have a tool box, that can double as a seat for each intended occupant.

• Not contain equipment in such a manner as to obstruct the occupant’s foothold or handhold.

• Have a chain or hinged bar across the opening to prevent a diver from falling out.

• Be fitted with onboard air reserve and fittings to support the anticipated number of divers at the maximum working depth for a period of 10 minutes. This will normally be by provision of 1 “G” size cylinder.

Reference DOF Subsea DOM Section 7.4.7.

1.3.8 Cutting Equipment

Cutting equipment must be tested prior to deployment. Refer to the DOF Subsea DOM Section 8.7.10 for safety checks prior to use.

Under no circumstances shall cutting equipment be made hot without prior approval from the site PIC (OIM / Vessel Master) and welder/electrician (where applicable).

1.3.9 Communications

Establish channels to be used with vessel Master / rig or platform and cranes. For diving tasks, a dedicated channel is preferable over a client working channel. Fully brief crane drivers, winch/tugger operators, etc., of diving requirements. Refer to section on Dive Briefings which follows this section.

1.3.10 Diving Equipment General

Check all other equipment required for the project. Refer to section 0 for details of Diver Dress. Pay particular attention to the following:

• Dive torches, spare batteries and globes.

• Tools are sufficient for the tasks at hand and operable.

• Weight belts are to contain enough weight and be of sufficient size and are not to be of the quick release type.

• Diver knives are in good working order and sharpened.



• Harnesses must have crutch straps, buckles, a D ring for lifting and are to be non-quick release type.

• Fins are of the correct size with spare pairs and fin straps being held.

• Spares: Check the system inventory and manifests to ensure sufficient spares are stored as tasks and work scopes may change during the course of the project necessitating more of some items than originally envisaged.



1.4 DIVE TASK BRIEFINGS

It is imperative that the Dive Supervisor briefs the diver and preferably the entire dive crew on each task required of them and the sequence of events leading to those tasks being performed. Reference DOF Subsea DOM Section 3.1.4.

Once the Diving Supervisor and crew have been briefed, others involved in the task, such as crane and tugger operators, must also be briefed on tasks required of them and the difficulties divers experience underwater that are not evident with similar work on the surface.

1.4.1 Operator Briefings

Briefings to winch / crane / tugger operators, etc., should include the following:

• Ensure the operator is aware of what is happening, and the reason for it.

• Ensure he is familiar with the equipment being used and how it is to be used in this application.

• Check to see, in the case of cranes and tuggers, that there is sufficient wire to reach the bottom.

• Instruct the operator and rigger on how the item to be lifted is to be rigged on the surface to make it diver friendly.

• Insist on all commands being repeated back. This should be common practice which will not only facilitate productivity but will also safeguard the diver when working with heavy or awkward loads in the water.

1.4.2 Vessel Master / PIC Briefings

Most PIC’s (Vessel Masters / OIM’s) supporting diving operations are fully aware of what is required of them, their vessel / facility and crew whilst diving operations are taking place, but a briefing to them must include the following.

• Vessel engines must be switched off and isolated whilst divers are in the water (except when the vessel is in DP mode). They must not be started until the Diving Supervisor gives the all clear to do so.

• Impressed current systems must be switched off prior to diving, and again not switched on until the diver Supervisor gives the all clear to do so.

• In certain circumstances, it may be safe for another vessel to come alongside whilst diving is being conducted, but this may only be done if the Diving Supervisor and PIC give permission to do so.

• Check the location of sea water intakes and be aware of their status whilst diving. This may necessitate communications with the faciltiy engineer as well as the PIC.



• When moored to a structure, rather than tied up to it, two mooring lines must be used at each corner of the vessel closest to the structure.

• When using air lifts or pneumatic tools from a vessel, warn the ship's Master and/or engineer of the possibility of air being taken up into the ship's sea water intakes.



1.5 EMERGENCY DRILLS

The conduct of all emergency drills should be discussed prior to the drill being conducted, although the dive Supervisor should always consider drills to ‘test’ the responsiveness of the dive team.

During drills, some common steps should be followed:

• The standby diver shall always follow the diver’s umbilical.

• The Supervisor shall give air to both divers’ pneumo hoses.

• The standby diver shall always free flow the mask of an unconscious diver.

1.5.1 Daily Checks

The following daily checks are to be performed on diving equipment as listed. These constitute the minimum checks required prior to use.

NOTE: These Daily Checks are additional to and do not replace the Pre-Dive Checks – see section 1.6.

Type Daily Checks

Hats and Band Masks

• Confirm maintenance log book is up to date.

• Non return valve is to be checked.

• Communications at hat, hose and radio.

• Check oral nasal in place and clean.

• Check butterfly valves secure.

• Check hood band secure.

• Check neck dam is correctly fitted.

• Confirm there is no tension on marsh marine.

• Flow test free flow.

• Test bail out through hat.

• Observe general condition of hat.

NOTE: Personnel utilising a KM Superlite helmet shall ensure that particular attention is paid to the correct functioning of the clamping and locking mechanisms between the helmet and yoke. Modifications to the lock plunger shall only have been made in accordance with DOF Subsea approved methods



Compressors

• Confirm maintenance log book is up to date.

• Compressor oil level is correct.

• Engine oil level is correct.

• Check belt tension.

• Check belt condition.

• Drain volume tank.

• Drain water trap.

• Drain filters.

• Log hours run at end of day - running total.

• Check running total, hours since last oil change.

• Check electrical compressor is switched off if not in use.

• Check fuel level and top up at end of shift.

Bailouts • Check pressure and top up if necessary prior to every dive

Deck Decompression Chamber

• Check chamber is at depth and prepared for use. Refer to 1.6.4 (DDC Prompt lists).

Dive Panel and Radio

• Communication checks to be made on all radios and are to include, diver radio, bull horn and radio contact to bridge, platform Supervisor, drill floor, etc.

• Check LP and HP air supply to panel and hats by function testing both



1.6 PRE-DIVE CHECKS

The responsible person shall ensure the following is completed

Responsible Position

Checks

Dive Supervisor • Dive Control Panel Prompt lists (see 1.6.1).

• Divers Equipment Prompt lists (see 1.6.2).

• LP Compressor Prompt lists (see 1.6.3).

• DDC Prompt lists (see 1.6.4).

• LARS Prompt lists (see 1.6.5).

• Ensure diver, standby diver and surface crew have completed their pre-dive checks (Reference 1.6.2 and 0).

NOTE: These checks shall be noted and logged in the Daily Log Book.

• Necessary documents (Diving Project Plan, decompression scheduled, company manuals, dive sheets) stop watches etc. are available.

• Dive team is briefed and stations assigned with tasks understood.

• Support personnel ready and understand tasks.

• Standby boat advised of impending dive and is in position, if applicable.

• Environmental conditions suitable for air diving.

• All relevant permits signed and in date.

Diver • A full understanding of the job to be done.

• Understanding of the decompression procedures.

• Checking of the equipment he will be using (see 1.6.2 and 0).

• Checks that the tools for the task and the emergency tools are in the diving cage.

• Full understanding of the emergency procedures.

Standby Diver • A full understanding of the job to be done.

• Understanding of the decompression procedures.



• Checking of the equipment he will be using.

• Full understanding of the emergency procedures as outlined in the Emergency Procedures section of this manual.

Support Crew The support crew shall prepare, and function check equipment used in association with the air diving operation. During an air diving operation they will confirm the following to the Diving Supervisor:-

• Communications checked and opened to the Diving Supervisor.

• Checks have been carried out on the DDC and it is ready for use.

• The low pressure compressor is checked and running.

• Power to the LARS and LARS functioning correctly.

• Any extra equipment required is on hand, checked and ready for use.

• Divers are dressed in and checked, ready to launch the stage.

• Personnel are tending the diver’s and standby diver’s umbilicals.



1.6.1 Dive Control Panel Prompt Lists

DOF SUBSEA DIVE CONTROL PANEL PROMPT LIST

NO ITEMS ACTION

1. Decompression schedules, company diving manual, treatment tables, dive sheets, pencil, pad, screw driver and small crescent wrench, torch

Ensure all are available

2. Stopwatches, tape recorder, torch Check for correct operation

3. Air in quads Analyse and check contents

4. Gas in quads (EAD & Gas Diving) Analyse and check contents

5. LP Air To Control Panel Ensure all valves are open to air regulator

6. Control Panel Valves Ensure all are in correct positions and main air to diver after bailout checked

7. Communications to: Divers 1 & 2, any external bull horns in use, bridge and to ROV Control Room

Check for correct operation (both ways)

Check Recording

8 Video System (Camera) Check for correct operation

Check Recording

9 Standby boat Ensure crew are briefed and in position for the dive

10 Whips, divers hoses and communications lines

Ensure all are protected and clear of the deck working areas

11. Permit To Dive or Dive Clearance Check that a Permit To Dive has been issued and signed as required. Take note of any special precautions or restrictions



1.6.2 Diver’s Equipment Prompt List

DOF SUBSEA DIVER’S EQUIPMENT PROMPT LIST

NO ITEMS ACTION

1. Communication between Divers mask and control panel


2. Mask / Helmet attachments, spider and hood / liner

Inspect for corrosion and for any damage

3. Mask / Helmet non-return valve Check for correct operation

4. Mask / Helmet air supply Check that air is available on demand and also free flow

5. Weight belt Inspect for corrosion and damage. Ensure correct amount of weight

6. Harness Inspect for any tears or damage

7. Fins and gloves Inspect for damage and correct fit

8. Knife and scabbard Inspect for corrosion and damage. Ensure blade is sharp and that the knife is positioned within easy reach of the diver’s hands

9. Torch Function check

10. Umbilical “D” ring and karabiner Inspect for corrosion and damage. Check for correct operation

11. Air / gas quad valves Ensure all are fully open

12. Air / Gas Supply Ensure air / gas is “on line” to the divers helmet / mask and that the reserve supply is available

13. Bail-out cylinder Check contents pressure. Ensure correct operation to helmet / mask

14. Tools Ensure the necessary tools are available and in good condition

15. Job Instructions Ensure instructions are clear and understood by all parties

16. Weather / Prevailing conditions Check on latest weather forecast and for any tidal currents that may interfere with diving operations



1.6.3 LP Air Compressor Prompt List

DOF SUBSEA LP AIR COMPRESSOR PROMPT LIST

NO ITEMS ACTION

1. Fuel and oil Check and replenish if necessary

2. Fan Belt Check tension, adjust if necessary

3. Compressor Check operation of starter (electric or manual)

Check rotation

4. Unloader Ensure that the compressor is loading and unloading at correct pressures

5. Volume tank and water taps Draw off any excess water

6. Safety relief valve Check for operation by manually lifting

7. Oil and air pressures Ensure operation within their limits

8. Compressor to control panel valves

Ensure valves are open

9. Filter Ensure filter is clean and within recommended change date

10. Air intakes Ensure not obstructed and not in vicinity of engine exhaust or other atmospheric contaminates

11 Air Analysis I within 3 months of last test



1.6.4 DDC Prompt List

DOF SUBSEA DDC PROMPT LIST

NO ITEMS ACTION

1. All interior and exterior valves. Ensure all are operable and in their correct position

2. All hatch ”O” rings Ensure in good condition

3 Stopper plugs for external drain penetrators

Ensure plugs seal

4 Oxygen masks Ensure sufficient BIBS are available in each compartment and operating correctly. Check overboard dump is working and vent mask on completion

5 Blankets, towels and dry clothes Ensure availability as required

6. Communications, lights, scrubber and heaters

Ensure correct operation

7. Oxygen bottles / quads Check contents and regulator for operation

8 Depth gauges Check for correct operation and are within 6 monthly examination date

9 Decompression tables, treatment tables, pencil, stopwatches




1.6.5 LARS Prompt List

DOF SUBSEA LARS PROMPT LIST

NO ITEMS ACTION

CHECK

1. Hydraulic Power Pack Check Operation of Starter

2. Check Hydraulic pressure

3. Check Hydraulic Hoses for Leaks

4. If Diesel Check fuel and lubes

5. Valves and Controls Function check for Operation and Direction

6. Main Lift Wires Visually check condition i.e. Lubrication, signs of corrosion. Test is in date

7. Swivels Visual Inspection for wear and corrosion. Test in date

8. Shackles Visual Inspection for wear and corrosion. The nut on the shackle bolts are drilled and pinned or have a castellated nut with a split pin

9. Sheaves Visual check for abnormalities

10. Stages Emergency air bottle fully charged and secure. 1st Stage regulator operational

11. Personnel restraining chain secure

12. Tooling for the job Any tooling for the job in the stage and secure

*** Note where split pins are used as retainers on Clevis pins or similar connections, they are to be used in conjunction with castellated nuts or Drilled and pinned nuts.



1.6.6 Dress

The minimum DOF Subsea standard dress for all diving projects will be as follows.

• Booties or weighted dive boots.

• Fins must be worn or taken by the diver on all dives with the exception of when weighted boots are worn.

Supervisor’s may use their discretion if a documented risk assessment is completed.

Weighted dive boots

are only to be worn with permission from the Dive Supervisor who must take into account local conditions such as current and swell, nature of the task and distance from the diving platform.

A dive knife to be worn of the fixed blade variety, housed in a sheath and secured by a lanyard, personal knives may be worn in addition to this.

Dive coveralls with full length sleeves and legs and/or full length wet suits. The thickness of a wet suit should be determined by local conditions but both hyper and hypothermia must be kept in mind when selecting wet suits for use.

Diver harness of the crutch type with a lifting D-ring and hose securing D-ring. Only DOF Subsea approved harness are to be used.

The diver's weight belt

must be of the non quick-release type.

Diving gloves must be worn at all times. Personal diving gloves may be worn, providing they are approved by the site Diving Supervisor.

A bailout regardless of depth and nature of the task, must be worn on all diving tasks. The bailout must be of a suitable size and contain sufficient pressure and volume to cater for the depth of water in which the diving tasks will be performed. Comfort of the diver will not override the need to supply sufficient air to the diver in an emergency situation.

The diver's hat or helmet

Must meet the requirement of the DOF Subsea DOM Section 7.4.4

Any tools taken to the job must either be secured to the diver's harness with a lanyard or, if hand-carried, or placed in the tool basket. All DOF Subsea tools, cameras, CP meters, etc., as far as practicable, will not be used underwater without a lanyard. Tools should have a lanyard attached to enable securing on the work site.



1.7 LIFELINE SIGNALS (AS PER AS2299.1: 2007)

Although it is recognised that diving shall not generally take place unless radio communication is available between the diver and Supervisor, it is acknowledged that circumstances may exist whereby divers will need to rely on line signals as a means of communication.

This may be a planned onshore dive or the means by which a dive is completed or terminated due to a communications failure offshore.

1.7.1 Types of Signals

Signals are of two kinds, as follows:

• Pulls - Long, steady and distinct pulls.

• Bells - Short, sharp bell pulls, or 'bells', made with the same timing as the striking of a ship's bell (i.e. one after another).

Pulls and bells shall never be made violently.

Single-Lifeline Code (As per AS/NZS2299.1: 2007).

Routine Lifeline Signals, however, are listed below.



1.7.2 Attendant to Diver

General Signals

1 pull To call attention. Are you okay?

2 pulls Am sending down a rope's end (or as previously arranged)

3 pulls You have come up too far Go down slowly until we stop you

4 pulls Come up

4 pulls followed by 2 bells Come up, hurry up, or come, surface decompression

Direction Signals

1 pull Search where you are

2 bells Go to the end of distance line or jackstay

3 bells Face shot line then go right

4 bells Face shot line then go left

5 bells Come into your shot line, or turn back if on a jackstay

1.7.3 Diver to Attendant

General Signals

1 pull To call attention / Made bottom / Left bottom / Reached end of jackstay / I am well

2 pulls Send me down a rope's end (or as previously arranged)

3 pulls I am going down

4 pulls May I come up?

4 pulls followed by 2 bells I want to come up. Assist me up

Emergency Signals

Succession of pulls (must be more than 4)

EMERGENCY SIGNAL Pull me up IMMEDIATELY

Succession of 2 bells Am fouled and need the assistance of another diver

Succession of 3 bells Am fouled but can clear myself if left alone

Working Signals

1 pull Hold on or stop

2 bells Pull up

3 bells Lower

4 bells Take up slack lifeline, or You are holding me too tight

5 bells Have found, started, or completed work



1.7.4 Hand Signals

Shown here are the hand signals most commonly required for diving.

Note: that variations in other underwater signals exist between training organisations. The diver should be made aware of such variations as appropriate.



1.8 DEMOBILISATION

Before the project is completed, the Diving Supervisor must receive, formal plans and directions for demobilisation, where the equipment is to be stored, how it is to be transported and the likely duration of storage before deployment again.

The nature of DOF Subsea operations is that Dive Systems or individual items will be transported many times during use. They may be moved by truck, lifted by cranes, dropped onto decks and subject to wild movement on vessels at sea.

There is potential for damage to DOF Subsea diving equipment during this period. It is therefore important that equipment be adequately and appropriately packed having in mind the length of the journey and the type of hazards likely to be encountered.

The following is a list of precautions to be taken:

• Secure loose items inside containers.

• Pad fragile items.

• Don’t put heavy items on top of other items.

• Secure lids on liquid containers.

• Cover against the elements - rain, heat, dust, and humidity.

• Protect against items rubbing against other items.

• Chamber doors secured, pressure in locks, exhausts secured and closed.

Commonsense is to be used when assessing the likely risks of damage during transit and the steps to be taken to minimise the risk.



1.8.1 Demobilisation checklist

Before demobilisation, complete the following:

1 Liaise with the local Supervisor responsible for transport to ascertain times and type of transport available.

2 Complete an inventory, ensuring that all consumables used are on daily reports and all deficiencies are requested on a stores requisition form.

3 Check air compressors for gas analysis dates and ensure the system gauges will be in calibration for the next diving period.

4 The levels of the O2 and air quads are to be recorded on a Gas Status Sheet on completion of each job.

5 Any damage to quads should be advised to DOF Subsea. This includes damage to or loss of the chain on the top of the quad.

6 Please ensure that quad numbers are used and that dates, job numbers and system numbers are endorsed on the Status sheet. The quad numbers to be reported are in the following format: a) WA 019 or b) WAA 319 etc.

The numbers are generally welded onto the frame of the quad.

7 Depressurise all whips, tape the ends and clean externally if required.

8 Back off all regulators and wash in clean, fresh water, dry and store in a secure place.

9 When O2 analysers are to be stored, remove the O2 fuel cell and seal it inside a plastic bag. This stops the fuel cell reaction and greatly extends the life of the cell.

10 Where possible all radio batteries are to be fully charged prior to the end of the project. In any case at least one battery should be fully charged.

11 Ensure adequate craneage.

12 Check lifting points in certification.

13 Postpone loading if weather not conducive to safe operations.

14 Ensure system sea-fastened. Conduct this check with the vessel engineer.

15 Ensure trucking sufficient for load.

16 A Project Debrief shall be carried out with the Diving Supervisor at the completion of every job. The Debrief Sheet shall be completed. by the Project / Operations Manager.



2.0 DIVING PROCEDURES – US NAVY DECOMPRESSION TABLES

2.1 US NAVY DECOMPRESSION TABLES

DOF Subsea has chosen the USN Air Decompression Tables for use during air diving operations to 50 metres. DOF Subsea also uses the DCIEM Decompression Tables for air diving operations when it is appropriate to do so.

The DOF Subsea Diving Manager will determine as part of the DPP and JHA which tables are to be used for the specific diving operation being undertaken.

2.1.1.1 Warning

Under no circumstances shall US Navy and DCIEM Air Decompression Tables be used concurrently on the same diving task or within 24 hours of a previous diving task using one or the other table. Serious debilitating decompression illness can result from such practice as the tables were developed independently of each other using quite different procedures and principles. For example:

• Within a 24 hour period do not use the US Navy table for the first dive and then switch to the DCIEM tables for the second dive (or vice-a-versa).

• Do not complete a dive on day one using DCIEM Tables and the next day (day two, 20 hours later) undertake another dive using US Navy Tables.



2.1.2 Air Decompression Definitions

The following terms are frequently used when conducting diving operations and discussing the decompression tables.

Term Description

Descent Time Descent time is the total elapsed time from when the divers leave the surface to the time they reach the bottom. Descent time is rounded up to the next whole minute.

Bottom Time. Bottom time is the total elapsed time from when the divers leave the surface to the time they that they begin their final ascent from the bottom. Bottom time is measured in minutes and is rounded up to the next whole minute.

Decompression Table A decompression table is a structured set of decompression schedules, or limits, usually organised in order of increasing bottom times and depths.

Decompression Schedule. A decompression schedule is a specific decompression procedure for a given combination of depth and bottom time as listed in a decompression table. It is normally indicated as feet/minutes.

Decompression Stop A decompression stop is a specified depth where a diver must remain for a specified length of time (stop time). NOTE: Diver’s chest should be located as closely as possible to the stop depth.

Depth. The following terms are used to indicate the depth of a dive:

• Deepest Depth: is the deepest pnuemo reading obtained when conducting surface supplied diving or the deepest depth gauge reading when conducting scuba operations.

• Maximum Depth is the deepest depth attained by the diver plus the pneumofathometer correction factor (Table below). When conducting scuba operations, maximum depth is the deepest depth gauge reading.

• Stage Depth is the pneumofathometer reading taken when the divers are on the stage just prior to leaving the bottom. Stage depth is used to compute distance and travel time to the first stop, or to the surface if no stops are required.



Pneumofathometer Correction Factors

PNEUMOFATHOMETER DEPTH CORRECTION FACTOR

0-100 FSW

101-200 FSW

201-300 FSW

301-400 FSW

+1 FSW

+2 FSW

+4 FSW

+7 FSW

Equivalent Single Dive Bottom Time.

The equivalent single bottom time is the time used to select a schedule for a single repetitive dive. This time is expressed in minutes.

Unlimited/No Decompression (No “D”) Limit

The maximum time that can be spent at a given depth so that safe ascent can be made directly to the surface at a prescribed travel rate with no decompression stops is the unlimited/no-decompression or No “D” limit.

Limiting Line The depth segments in;

• Standard Air Decompression Tables; (Table 2.3.1)

• Surface Decompression Table Using Oxygen; (Table 2.4.6)

• Surface Decompression Table Using Air; (Table 2.5.1)

are divided into two sections by a limiting line. This limiting line corresponds to the line dividing the “normal air range” and “exceptional exposure range”. The shaded areas below each limiting line (a double bolded line in each depth increment) in the tables highlight dive profiles which are in the “exceptional exposure range”. The DOF Subsea limiting line may be at variance to those published in Chapter 9 of the USN Diving Manual. DOF Subsea has increased the safety margin1, in some instances, by enlarging the “exceptional exposure range” in the depth increment.

1 It is standard industry practice to limit total combined decompression times, in water, to a

maximum of approximately 30 minutes . The limiting line reflects this policy.



Repetitive Dive. A repetitive dive is any dive conducted more than 10 minutes and within 12 hours of a previous dive.

NOTE: DOF Subsea prohibits repetitive diving using any USN Table. Accumulative diving (as described in 2.1.3), however, is permitted

Repetitive Group Designation.

The repetitive group designation is a letter used to indicate the amount of residual nitrogen remaining in a diver's body following a previous dive.

Residual Nitrogen Residual nitrogen is the nitrogen gas that is still dissolved in a diver's tissues after surfacing.

Residual Nitrogen Time. Residual nitrogen time is the time that must be added to the bottom time of a repetitive dive to compensate for the nitrogen still in solution in a diver’s tissues from a previous dive. Residual nitrogen time is expressed in minutes.

Single Dive. A single dive refers to any dive conducted more than 12 hours after a previous dive.

Single Repetitive Dive A single repetitive dive is a dive for which the bottom time used to select the decompression schedule is the sum of the residual nitrogen time and the actual bottom time of the dive.

Surface Interval The surface interval is the time that a diver has spent on the surface following a dive. It begins as soon as the diver surfaces and ends as soon as he starts his next descent.

2.1.3 Accumulative Dives

While DOF Subsea prohibits repetitive dives using any USN Table, accumulative dives are permitted. When one diver is conducting multiple dives in a 12 hour period, the bottom depth used is always the deepest depth of the series of dives and the bottom times are added together to gain the Total Bottom Time. There is no allowance for Surface Interval or Residual Nitrogen Times.

Example

• Dive 1, 63 feet for 12 minutes,

• Dive 2, 42 feet for 15 minutes.

• Dive 2 Decompression Schedule is assessed on a depth 63 feet and the Total Bottom Time of 27 minutes.



2.2 TABLE SELECTION

The following US Navy decompression tables are available for DOF Subsea diving operations:

• Unlimited/No-Decompression Limits and Repetitive Group Designation Table for No-Decompression Air Dives.

• Standard Air Decompression Table.

• Surface Decompression Table Using Oxygen.

• Surface Decompression Table Using Air.

• Therapeutic Tables (see section 2.6.4 and 2.6.5).

2.2.1 Selection of Decompression Schedule

DOF Subsea uses a modified USN Decompression Table using Oxygen. These tables present a series of decompression schedules which must be rigidly followed during ascent from an air dive. Each decompression table has specific conditions which justify its selection. These conditions are depth and duration of the dive, availability of an oxygen breathing system within the chamber, and environmental conditions such as sea state, water temperature etc.

The four air tables containing the pertinent criteria for the selection and application of each are listed below.

• US Navy Standard Air Decompression Table - Conditions dictate that in-water decompression permissible. Normal schedules. No repetitive dives; normal decompression schedules only.

• No Decompression Limits and Repetitive Group Designation Table for No-Decompression Air Dives - Decompression not required.

NOTE: Again DOF Subsea prohibits repetitive diving using any USN Table. Accumulative dives, however, are permissible.

• Residual Nitrogen Time Table for Repetitive Air Dives, this table is not to be used for operations - Repetitive group designations after surface intervals greater than 10 minutes and less than 12 hours. Residual nitrogen times for repetitive air dives.

• DOF Subsea Modified USN Surface Decompression Table Using Oxygen - Available decompression chamber with oxygen breathing system. Conditions dictate in-water decompression undesirable. Accumulative diving permitted.

• Surface Decompression Table Using Air - Available decompression chamber without an oxygen breathing system; or diver forced to surface prior to completing decompression. Conditions dictate in-water decompression undesirable. Accumulative dives permitted. Diver suffers oxygen toxicity.



The decompression schedules of all the tables are usually given in 10 foot depth increments and 10 minute bottom time increments. Depth and bottom time combinations from dives, however, rarely match the decompression schedules listed exactly. To ensure that the selected decompression schedule is always conservative:

• Always select the schedule depth equal to or next greater than the maximum depth of the dive and

• Always select the schedule bottom time equal to or next longer than the bottom time of the dive and then move to the next time increment.

CAUTION: Never attempt to interpolate between decompression schedules.

With reference to paragraph, above, if the diver was exceptionally cold during the dive or if the work load is relatively strenuous, the next longer decompression schedule than the one they would normally follow should be selected.

Therefore it is mandatory for all DOF Subsea supervisors to decompress divers in accordance with the next “time increment” one above the divers actual bottom time. For cold and strenuous work supervisors will be required to decompress divers in accordance with the time increment two above the divers actual bottom time.

Bottom times are not to exceed the times shown in the table at 8.5.6 in the DOF Subsea DOM.



2.2.2 Ascent Procedures

Term Requirement

Rules During Ascent. After selecting the applicable decompression schedule, it is imperative that it be followed as closely as possible. Unless a hyperbaric doctor recommends a deviation, decompression must be completed according to the schedule selected.

Ascent rate

Always ascend at a rate of 30 feet per minute. Minor variations in the rate of travel between 20 and 40 FSW/minute are acceptable. Any variation in the rate of ascent must be corrected in accordance with the procedures. However, a delay of up to one minute in reaching the first decompression stop can be ignored.

Decompression stop time

Decompression stop times, as specified in the decompression schedule, begin as soon as the divers reach the stop depth. Upon completion of the specified stop time, the divers ascend to the next stop or to the surface at the proper ascent rate. Ascent time is not included as part of stop time.

Variations in Rate of Ascent

The following rules for correcting variations in rate of ascent apply to Standard Air Decompression dives as well as Surface Decompression dives.

Delays in Arriving at the First Stop

Delay greater than 1 minute, deeper than 50 FSW. Add the total delay time (rounded up to the next whole minute) to the bottom time, recompute a new decompression schedule and decompress accordingly.

Delay greater than 1 minute, shallower than 50 FSW. If the rate of ascent is less than 30 fpm, add the delay time to the diver’s first decompression stop. If the delay is between stops, disregard the delay. The delay time is rounded up to the next whole minute.

Travel Rate Exceeded. On a Standard Air Dive, if the rate of ascent is greater than 30 feet per minute, STOP THE ASCENT, allow the watches to catch up, and then continue ascent. If the stop is arrived at early, start the stop time after the watches catch up.



2.2.3 Diving At High Altitudes

Because of the reduced atmospheric pressure, dives conducted at altitude require more decompression than identical dives conducted at sea level. Standard air decompression tables, therefore, cannot be used as written. Some organisations calculate specific decompression tables for use at each altitude. An alternative approach is to correct the altitude dive to obtain an equivalent sea level dive, then determine the decompression requirement using standard tables. This procedure is commonly known as the "Cross Correction” technique and always yields a sea level dive that is deeper than the actual dive at altitude. A deeper sea level equivalent dive provides the extra decompression needed to offset effects of diving at altitude.

2.2.3.1 Need for Correction

No correction is required for dives conducted at altitudes between sea level and 300 ft (100 metres). The additional risk associated with these dives is minimal.

In addition, where a dive is undertaken at an altitude of 1000 feet (300 metres), and the actual depth of dives is less than 145 FSW (42 metres) no correction is required.

At altitudes between 300 feet (100 metres) and 1000 feet (300 metres), correction is required for dives deeper than 145 FSW (42 metres) [actual depth]. At altitudes above 1000 ft., correction is required for all dives.

2.2.3.2 Procedure

Where a correction is required for dives at altitude, in accordance with paragraph 2.2.3.1 above, separate job specific DOF Subsea procedures will be provided. These procedures shall be developed with reference to Chapter 9 of the USN Diving Manual and detailed in the DPP.



2.2.4 Unlimited / No-Decompression Limits and Repetitive Group Designation Table for

No-Decompression Air Dives

The Unlimited / No-Decompression Table (2.2.4.3) serves three purposes;

• First, the table identifies that on a dive with the depth 20 FSW and shallower, unlimited bottom time may be achieved.

• Second, it summarises all the depth and bottom time combinations for which no decompression is required.

• Third, it provides the repetitive group designation for each unlimited/no-decompression dive. However, this is not used as DOF Subsea prohibits repetitive diving using USN Tables.

Each depth listed in the Unlimited / No-Decompression Table has a corresponding no-decompression limit listed in minutes. This limit is the maximum bottom time that the diver may spend at that depth without requiring decompression. Use the columns to the right of the no-decompression limits column to obtain the repetitive group designation. This designation must be assigned to the diver subsequent to every dive. To find the repetitive group designation:

• Enter the table at the depth equal to, or next greater than, the maximum depth of the dive.

• Follow that row to the right to the bottom time equal to, or just greater than, the actual bottom time of the dive.

• Follow that column upward to the repetitive group designation.

Depths shallower than 20 fsw do not have a specific no-decompression limit. The limits are, however, restricted in that they only provide repetitive group designations for bottom times up to 6 hours. These bottom times are considered the limitations of the No-Decompression Table and no field requirement for diving should extend beyond them.

Any dive deeper than 20 fsw which has a bottom time greater than the no-decompression limit given in this table is a decompression dive and must be conducted in accordance with the Standard Air Decompression Table.

2.2.4.1 Example:

In planning a dive, the Dive Supervisor desires the divers to conduct a brief inspection of the work site, located at a depth of 157 fsw. Determine the maximum no-decompression limit and repetitive designation.



2.2.4.2 Solution:

The maximum bottom time which may be used without requiring decompression and repetitive group designation after the dive are found in the No-Decompression Table or the US Navy Standard Air Decompression Table. The no-decompression limit corresponding to the 160 fsw depth in the No-Decompression Table is five minutes. Therefore, to avoid having to make decompression stops, the Diver must descend to 158 fsw, make the inspection, and begin ascent within five minutes.

Following the 160 fsw row to the 5 minute column, the repetitive group designation at the top of the column is D.

NOTE: Although repetitive diving is prohibited on USN Tables, the repetitive group is important as DOF Subsea bans dives in excess of an “O” group.



2.2.4.3 Table — Unlimited / No Decompression Limits and Repetitive Group Designation Table for Unlimited / No-Decompression Air Dives

2

Group Designation Depth

(feet/meters)

No-Deco

Limits (min) A B C D E F G H I J K L M N O

10 3.0 Unlimited 60 120 210 300 797 *

15 4.6 Unlimited 35 70 110 160 225 350 452 *

20 6.1 Unlimited 25 50 75 100 135 180 240 325 390 917 *

25 7.6 595 20 35 55 75 100 125 160 195 245 315 361 540 595

30 9.1 405 15 30 45 60 75 95 120 145 170 205 250 310 344 405

35 10.7 310 5 15 25 40 50 60 80 100 120 140 160 190 220 270 310

40 12.2 200 5 15 25 30 40 50 70 80 100 110 130 150 170 200

50 15.2 100 10 15 25 30 40 50 60 70 80 90 100

60 18.2 60 10 15 20 25 30 40 50 55 60

70 21.3 50 5 10 15 20 30 35 40 45 50

80 24.4 40 5 10 15 20 25 30 35 40

90 27.4 30 5 10 12 15 20 25 30

100 30.5 25 5 7 10 15 20 22 25

110 33.5 20 5 10 13 15 20

120 36.6 15 5 10 12 15

130 39.6 10 5 8 10

140 42.7 10 5 7 10

150 45.7 5 5

160 48.8 5 5

170 51.8 5 5

180 54.8 5 5

190 59.9 5 5

Highest repetitive group that can be achieved at this depth regardless of bottom time.

2 Taken from the US Navy Manual, Chapter 9, Table 9.6; 7 March 2000 (PDF Version 1.3)



2.3 US NAVY STANDARD AIR DECOMPRESSION TABLE

This Annexe has combined the Standard Air Decompression Table and Exceptional Exposure Air Schedules into one table as titled above. To clearly distinguish between the standard (normal) and exceptional exposure decompression schedules, the exceptional exposure schedules have double asterisks. DOF Subsea has added an operational limiting line.

If the bottom time of a dive is less than the first bottom time listed for its depth, decompression is not required. The divers may ascend directly to the surface at a rate of 30 feet per minute (fpm). The repetitive group designation for a no-decompression dive is given in the Unlimited / No-Decompression Table. As noted in the Standard Air Table, there are no repetitive group designations for exceptional exposure dives. Repetitive dives are not permitted following an exceptional exposure dive.

2.3.1 Table — US Navy Standard Air Decompression Table3

US Navy Standard Air Decompression Table

Decompression Stops (feet/meters)

Depth - feet

/meters

Bottom

Time

(min)

Time

first stop

(min:sec)

50

15.2

40

12.1

30

9.1

20

6.0

10

3.0

Total

Deco. time

(min:sec)

Repetitive

Group

200 0 1:20 *

210 1:00 2 3:20 N

230 1:00 7 8:20 N

250 1:00 11 12:20 O

270 1:00 15 16:20 O

300 1:00 19 20:20 Z

360 1:00 23 24:20 **

480 1:00 41 42:20 **

40

12.1

720 1:00 69 70:20 **

3 Taken from the US Navy Manual, Chapter 9 , Table 9.8; 7 March 2000 (PDF Version 1.3)





Depth - feet

/meters

Bottom

Time

(min)

Time

first stop

(min:sec)

50

15.2

40

12.1

30

9.1

20

6.0

10

3.0

Total

Deco. time

(min:sec)

Repetitive

Group

100 0 1:40 *

110 1:20 3 4:40 L

120 1:20 5 6:40 M

140 1:20 10 11:40 M

160 1:20 21 22:40 N

180 1:20 29 30:40 O

200 1:20 35 36:40 O

220 1:20 40 41:40 Z

50

15.2

240 1:20 47 48:40 Z

60 0 2:00 *

70 1:40 2 4:00 K

80 1:40 7 9:00 L

100 1:40 14 16:00 M

120 1:40 26 28:00 N

140 1:40 39 41:00 O

160 1:40 48 50:00 Z

180 1:40 56 58:00 Z

200 1:20 1 69 72:00 Z

240 1:20 2 79 83:00 **

360 1:20 20 119 141:00 **

480 1:20 44 148 194:00 **

60

18.1

720 1:20 78 187 267:00 ** * See No Decompression Table for repetitive groups

** Repetitive dives may not follow exceptional exposure dives





Depth - feet

/meters

Bottom

Time

(min)

Time

first stop

(min:sec)

50

15.2

40

12.1

30

9.1

20

6.0

10

3.0

Total

Deco. time

(min:sec)

Repetitive

Group

50 0 2:20 *

60 2:00 8 10:20 K

70 2:00 14 16:20 L

80 2:00 18 20:20 M

90 2:00 23 25:20 N

100 2:00 33 35:20 N

110 1:40 2 41 45:20 O

120 1:40 4 47 53:20 O

130 1:40 6 52 60:20 O

140 1:40 8 56 66:20 Z

150 1:40 9 61 72:20 Z

160 1:40 13 72 87:20 Z

70

21.3

170 1:40 19 79 100:20 Z





Depth - feet

/meters

Bottom

Time

(min)

Time

first stop

(min:sec)

50

15.2

40

12.1

30

9.1

20

6.0

10

3.0

Total

Deco. time

(min:sec)

Repetitive

Group

40 0 2:40 *

50 2:20 10 12:40 K

60 2:20 17 19:40 L

70 2:20 23 25:40 M

80 2:00 2 31 35:40 N

90 2:00 7 39 48:40 N

100 2:00 11 46 59:40 O

110 2:00 13 53 68:40 O

120 2:00 17 56 75:40 Z

130 2:00 19 63 84:40 Z

140 2:00 26 69 97:40 Z

150 2:00 32 77 111:40 Z

180 2:00 35 85 122:40 **

240 1:40 6 52 120 180:40 **

360 1:40 29 90 160 281:40 **

480 1:40 59 107 187 355:40 **

80

24.3

720 1:20 17 108 142 187 456:40 ** * See No Decompression Table for repetitive groups






Depth - feet

/meters

Bottom

Time

(min)

Time

first stop

(min:sec)

50

15.2

40

12.1

30

9.1

20

6.0

10

3.0

Total

Deco. time

(min:sec)

Repetitive

Group

30 0 3:00 *

40 2:40 7 10:00 J

50 2:40 18 21:00 L

60 2:40 25 28:00 M

70 2:20 7 30 40:00 N

80 2:20 13 40 56:00 N

90 2:20 18 48 69:00 O

100 2:20 21 54 78:00 Z

11 2:20 24 61 88:00 Z

120 2:20 32 68 103:00 Z

90

28.7

130 2:00 5 36 74 118:00 Z * See No Decompression Table for repetitive groups






Depth - feet

/meters

Bottom

Time

(min)

Time

first stop

(min:sec)

50

15.2

40

12.1

30

9.1

20

6.0

10

3.0

Total

Deco. time

(min:sec)

Repetitive

Group

25 0 3:20 *

30 3:00 3 6:20 I

40 3:00 15 18:20 K

50 2:40 2 24 29:20 L

60 2:40 9 28 40:20 N

70 2:40 17 39 59:20 O

80 2:40 23 48 74:20 O

90 2:20 3 23 57 86:20 Z

100 2:20 7 23 66 99:20 Z

110 2:20 10 34 72 119:20 Z

120 2:20 12 41 78 134:20 Z

180 2:00 1 29 53 118 204:20 **

240 2:00 14 42 84 142 285:20 **

360 1:40 2 42 73 111 187 418:20 **

480 1:40 21 61 91 142 187 505:20 **

100

30.4

720 1:40 55 106 122 142 187 615:20 ** * See No Decompression Table for repetitive groups






Depth - feet

/meters

Bottom

Time

(min)

Time

first stop

(min:sec)

50

15.2

40

12.1

30

9.1

20

6.0

10

3.0

Total

Deco. time

(min:sec)

Repetitive

Group

20 0 3:40 *

25 3:20 3 6:40 H

30 3:20 7 10:40 J

40 3:00 2 21 26:40 L

50 3:00 8 26 37:40 M

60 3:00 18 36 57:40 N

70 2:40 1 23 48 75:40 O

80 2:40 7 23 57 90:40 Z

90 2:40 12 30 64 109:40 Z

110

33.1

100 2:40 15 37 72 127:40 Z * See No Decompression Table for repetitive groups




US Navy Standard Air Decompression Table Decompression Stops (feet/meters)

Depth – feet

/metres

Bottom

time

(min)

Time

first stop

(min:sec) 70

21.3

60

18.2

50

15.2

40

12.1

30

9.1

20

6.0

10

3.0

Total

Deco. Time

(min:sec)

Repetitive

group

15 0 4:00 *

20 3:40 2 6:00 H

25 3:40 6 10:00 I

30 3:40 14 18:00 J

40 3:20 5 25 34:00 L

50 3:20 15 31 50:00 N

60 3:00 2 22 45 73:00 O

70 3:00 9 23 55 91:00 O

80 3:00 15 27 63 109:00 Z

90 3:00 19 37 74 134:00 Z

100 3:00 23 45 80 152:00 Z

120 2:40 10 19 47 98 178:00 **

180 2:20 5 27 37 76 137 286:00 **

240 2:20 23 35 60 97 179 398:00 **

360 2:00 18 45 64 93 142 187 553:00 **

480 1:40 3 41 64 93 122 142 187 656:00 **

120

36.5

720 1:40 32 74 100 114 122 142 187 775:00 **

10 0 4:20 *

15 4:00 1 5:20 F

20 4:00 4 8:20 H

25 4:00 10 14:20 J

30 3:40 3 18 25:20 M

40 3:40 10 25 39:20 N

50 3:20 3 21 37 65:20 O

60 3:20 9 23 52 88.20 Z

70 3:20 16 24 61 105:20 Z

80 3:00 3 19 35 72 133:20 Z

130

39.6

90 3:00 8 19 45 80 156:20 Z

* See No Decompression Table for repetitive groups






Depth feet

/ metres

Bottom

time

(min)

Time first

stop

(min:sec) 90

27.4

80

24.3

70

21.3

60

18.2

50

15.2

40

12.1

30

9.1

20

6.0

10

3.0

Total

deco. Time

(min:sec)

Repetitive

group

10 0 4:40 *

15 4:20 2 6:40 G

20 4:20 6 10:40 I

25 4:00 2 14 20:40 J

30 4:00 5 21 30:40 K

40 3:40 2 16 26 48:40 N

50 3:40 6 24 44 78:40 O

60 3:40 16 23 56 99:40 Z

70 3:20 4 19 32 68 127:40 Z

80 3:20 10 23 41 79 157:40 Z

90 3:00 2 14 18 42 88 168:40 **

120 3:00 12 14 36 56 120 242:40 **

180 2:40 10 26 32 54 94 168 388:40 **

240 2:20 8 28 34 50 78 124 187 513:40 **

360 2:00 9 32 42 64 84 122 142 187 686:40 **

480 2:00 31 44 59 100 114 122 142 187 803:40 **

140

42.6

720 1:40 16 56 88 97 100 114 122 142 187 926:40 **

5 0 5:00 C

10 4:40 1 6:00 E

15 4:40 3 8:00 G

20 4:20 2 7 14:00 H

25 4:20 4 17 26:00 K

30 4:20 8 24 37:00 L

40 4:00 5 19 33 62:00 N

50 4:00 12 23 51 91:00 O

60 3:40 3 19 26 62 115:00 Z

70 3:40 11 19 39 75 149:00 Z

150

45.7

80 3:20 1 17 19 50 84 176:00 Z





Depth feet

/ metres

Bottom

time

(min)

Time first

stop

(min:sec) 90

27.4

80

24.3

70

21.3

60

18.2

50

15.2

40

12.1

30

9.1

20

6.0

10

3.0

Total

deco. Time

(min:sec)

Repetitive

group

5 0 5:20 D

10 5:00 1 6:20 F

15 4:40 1 4 10:20 H

20 4:40 3 11 19:20 J

25 4:40 7 20 32:20 K

30 4:20 2 11 25 43:20 M

40 4:20 7 23 39 74:20 N

50 4:00 2 16 23 55 101:20 Z

60 4:00 9 19 33 69 135:20 Z

160

48.7

70 3:40 1 17 22 44 80 169:20 **

Depth feet/

metres

Bottom

time

(min)

Time

first stop

(min:sec

)

110

33.5

100

30.4

90

27.4

80

24.3

70

21.3

60

18.2

50

15.2

40

12.1

30

9.1

20

6.0

10

3.0

Total

deco. Time

(min:sec)

Repetitive

group

5 0 5:40 D

10 5:20 2 7:40 F

15 5:00 2 5 12:40 H

20 5:00 4 15 24:40 J

25 4:40 2 7 23 37:40 L

30 4:40 4 13 26 48:40 M

40 4:20 1 10 23 45 84:40 O

50 4:20 5 18 23 61 112:40 Z

60 4:00 2 15 22 37 74 155:40 Z

70 4:00 8 17 19 51 86 186:40 **

90 3:40 12 12 14 34 52 120 249:40 **

120 3:00 2 10 12 18 32 42 82 156 359:40 **

180 2:40 4 10 22 28 34 50 78 120 187 538:40 **

240 2:40 18 24 30 42 50 70 116 142 187 684:40 **

360 2:20 22 34 40 52 60 98 114 122 142 187 876:40 **

170

51.8

480 2:00 14 40 42 56 91 97 100 114 122 142 187 1010:40 **





Depth feet/

metres

Bottom

time

(min)

Time

first stop

(min:sec

)

110

33.5

100

30.4

90

27.4

80

24.3

70

21.3

60

18.2

50

15.2

40

12.1

30

9.1

20

6.0

10

3.0

Total

deco. Time

(min:sec)

Repetitive

group

5 0 6:00 D

10 5:40 3 9:00 F

15 5:20 3 6 15:00 I

20 5:00 1 5 17 29:00 K

25 5:00 3 10 24 43:00 L

30 5:00 6 17 27 56:00 N

40 4:40 3 14 23 50 96:00 O

50 4:20 2 9 19 30 65 131:00 Z

180

54.8

60 4:20 5 16 19 44 81 171:00 Z

5 5:40 0 6:20 D

10 5:40 1 3 10:20 G

15 5:40 4 7 17:20 I

20 5:20 2 6 20 34:20 K

25 5:20 5 11 25 47:20 M

30 5:00 1 8 19 32 66:20 N

40 5:00 8 14 23 55 106:20 O

50 4:40 4 13 22 33 72 150:20 **

190

57.9

60 4:40 10 17 19 50 84 186:20 **

* See No Decompression Table for repetitive groups




2.4 SURFACE DECOMPRESSION TABLE USING OXYGEN

Using the Surface Decompression Table Using Oxygen (referred to as SurD O2) requires an DOF Subsea approved double-lock recompression chamber with an oxygen breathing system as described in section 7.3 of the DOF Subsea DOM.

2.4.1 Procedure

With SurD O2, divers ascend at a constant rate of 30 fpm. The divers are decompressed to the first decompression stop (or to the surface if there are no water stops required) at an ascent rate of 30 fpm. The travel rate between stops and from 30 FSW to the surface is also 30 fpm (::204 per 10 FSW). Minor variations in the rate of travel between 20 and 40 fpm are acceptable.

Once the divers are on the surface, the tenders have three and a half (:03::30) minutes to remove the breathing apparatus and diving dress and assist the divers into the recompression chamber.

As soon as the divers enter the chamber they must begin breathing pure oxygen via the Built-in Breathing System (BIBS) mask. If the diver is alone inside the chamber then he is to hold the BIBS mask to his face. He is not to use the BIBS mask straps. Straps are only to be used if two or more divers are in the chamber together, (or at the discretion of the supervisor)

Pressurizing the recompression chamber with air to 50 FSW should take approximately 30 seconds (descent rate not to exceed 60 fpm). The total elapsed time from when the divers leave the 30-foot stop to when they reach the 50-foot recompression chamber stop must not exceed 5 minutes with the following exception:

“SAFE WAY OUT”

• If no in-water stops are required, the time from reaching the surface to arrival at 50 feet in the chamber must not exceed 4 minutes. During descent in the recompression chamber, if a diver cannot clear and the chamber is at a depth of at least 20 FSW, stop, then breathe oxygen at 20 FSW for twice the 40 FSW chamber stop time.

• Ascend to 10 FSW and breathe oxygen again for twice the 40 FSW chamber stop time. Then ascend to the surface.

This “safe way out” procedure is not intended to be used in place of normal SurD O2 procedures.

If the prescribed surface interval is exceeded and the divers are asymptomatic, treat them using the USN Table 5 – See 2.6.4. If the divers are symptomatic, they are treated as if they have DCI (Treatment USN Table 6 – See 2.6.5) even if they are only displaying minor symptoms. Symptoms occurring during the chamber stops are treated as recurrences.

4 The symbol “hh:mm” denotes hours and minutes. The symbol “mm::ss” denotes minutes and

seconds. Therefore “:03::30” means 3 minutes and 30 seconds.



The divers are to remain on oxygen at 50 FSW and whilst transferring to the main lock. The diver is to be held at 50 FSW for a period of 10 minutes during which time the entry/outer lock is to be brought back to the surface.

At the completion of the 10 minute stay at 50 FSW ascend to 40 FSW in 1 minute (10 fpm). When the chamber reaches 40 FSW the divers are to be given a 5 minute air break prior to starting the 40 FSW oxygen time.

At the completion of the 5 minute air break, the divers are again placed on the Built-in Breathing System (BIBS) mask breathing pure oxygen. The designated 40-foot stop time commences once the divers are breathing oxygen. The divers breathe oxygen throughout the 40-foot stop, interrupting oxygen breathing after each 20 minutes with a 5-minute period of breathing chamber air (referred to as an “air break”). Count the air breaks as “dead time” and not part of the oxygen stop time. If the air break interval falls on time to travel, leave the diver on O2 and commence travelling to the surface.

Maintain the diver on the O2 mask prior to leaving the 40 FSW stop for the surface.

Upon completion of the total oxygen breathing time at 40 FSW, surface the diver in 10 minutes at a constant rate of 4 fpm. The diver breathes oxygen during the entire ascent. This oxygen is in addition to the total time spent at 40' dictated by the table.

2.4.2 Oxygen System Failure (40-FSW Chamber Stop).

Follow this procedure when there is an oxygen system failure at the 50 or 40 FSW chamber stop:

• If the oxygen breathing system fails, the diver should be decompressed according to the surface decompression using air procedures (see 2.5).

• Disregard all time spent breathing oxygen.

• It is important that all DOF Subsea Supervisors be aware of the appropriate Surface Decompression Table Using Air at all times.



2.4.3 CNS Oxygen Toxicity (40-FSW Chamber Stop).

Follow this procedure when a diver displays symptoms of CNS O2 toxicity at either the 50 or 40 FSW chamber stop:

1 Remove the BIBS masks from the divers.

2 Attendant to enter the chamber to render assistance.

3 Wait for all symptoms to completely subside, then wait an additional 15 minutes.

4 Place the divers back on oxygen and resume the decompression at the point of interruption.

The period the divers are not breathing oxygen is considered “dead time” and is not counted toward the total stop time. This procedure can be repeated as many times as the Dive Supervisor considers prudent until all the required time spent breathing oxygen at 40 FSW is met.

If the Dive Supervisor decides that the diver cannot tolerate oxygen:

5 The diver should be removed from O2, and decompressed according to the surface decompression using air procedures (see 2.5).

6 Disregard all time spent breathing oxygen.

It is important that all DOF Subsea Supervisors be aware of the appropriate surface decompression using air procedures (see 2.5).



2.4.4 Convulsions at the 40-FSW Chamber Stop.

NOTE: If the first symptom of O2 toxicity at the 50 or 40 FSW stop is a convulsion, oxygen must not be restarted.

Follow this procedure when a diver convulses at the 40-FSW chamber stop:

1 Remove the BIBS mask.

2 Attendant to enter the chamber to render assistance.

3 Keep the chamber depth constant at 40 FSW. Wait for the convulsion to stop, ensuring the diver is breathing. The diver breathes air until regaining consciousness and all symptoms resolve.

4 The diver should now be decompressed according to the Surface Decompression Table Using Air.

5 Disregard all time spent breathing oxygen.

It is important that all DOF Subsea Supervisors be aware of the appropriate surface decompression using air procedures (see 2.5) at all times.

2.4.5 Repetitive Dives.

Divers are not to undertake a repetitive dive following a dive involving surface decompression.



2.4.6 Table – Surface Decompression Using Oxygen5

US Navy Surface Decompression Using Oxygen Table

Time (min) breathing air

at water stops (feet/metres)

Time in chamber

on oxygen

Depth

feet/metres

Bottom

Time

(min)

Time to

1st Stop

80

24.3

70

21.3

60

18.2

50

15.2

40

12.1

30

9.1

Surface

Interval

50

15.2

40

12.1 Ascent

Total

deco. time

(min:sec)

50 2:20 2:20

90 1:20 3 5 10 15 10 50:20

120 1:20 3 5 10 23 10 63:20

150 1:20 3 5 10 31 10 71:20

70

21.3 180 1:20 3 5 10 39 10 79:20

40 2:40 2:40

70 1:40 3 5 10 14 10 49:40

85 1:40 3 5 10 20 10 60:40

100 1:40 3 5 10 26 10 66:40

115 1:40 3 5 10 31 10 71:40

130 1:40 3 5 10 37 10 77:40

80

24.3 150 1:40 3 5 10 44 10 89:40

30 3:00 3:00

60 2:00 3 5 10 14 10 50:00

70 2:00 3 5 10 20 10 61:00

80 2:00 3 5 10 25 10 66:00

90 2:00 3 5 10 30 10 71:00

100 2:00 3 5 10 34 10 75:00

110 2:00 3 5 10 39 10 80:00

120 2:00 3 5 10 43 10 89:00

90

27.3

130 2:00 3 5 10 48 10 94:00

1. 5 min air break for every 20 min on O2.

2. Remain on O2 if time to travel during 20 min O2 period.

3. Max surface interval is 5 min from 30ft (may be less, but not more).

4. Ascent time in water 30 fpm.

5 Taken from the US Navy Manual, Chapter 9, Table 9-9; 7 March 2000 (PDF Version 1.3)






Time in chamber

on oxygen

Depth

feet/metres

Bottom

Time

(min)

Time to

1st Stop

80

24.3

70

21.3

60

18.2

50

15.2

40

12.1

30

9.1

Surface

Interval

50

15.2

40

12.1 Ascent

Total

deco. time

(min:sec)

25 3:20 3:20

50 2:20 3 5 10 14 10 50:20

60 2:20 3 5 10 20 10 61:20

70 2:20 3 5 10 26 10 67:20

80 2:20 3 5 10 32 10 73:20

90 2:20 3 5 10 38 10 79:20

100 2:20 3 5 10 44 10 90:20

110 2:20 3 5 10 49 10 95:20

100

30.4

120 2:00 2 4 5 10 53 10 102:20

20 3:40 3:40

40 2:40 3 5 10 12 10 48:40

50 2:40 3 5 10 19 10 55:40

60 2:40 3 5 10 26 10 67:40

70 2:40 3 5 10 33 10 74:40

80 2:20 2 3 5 10 40 10 88:40

90 2:20 2 4 5 10 46 10 95:40

100 2:20 2 5 5 10 51 10 101:40

110

33.5

110 2:20 2 12 5 10 54 10 111:40

15 4:00 4:00

30 3:00 3 5 10 9 10 46:00

40 3:00 3 5 10 16 10 53:00

50 3:00 3 5 10 24 10 66:00

60 2:40 2 3 5 10 32 10 76:00

70 2:40 2 4 5 10 39 10 84:00

80 2:40 2 5 5 10 46 10 97:00

120

36.5 90 2:40 4 8 5 10 51 10 107:00






Time in chamber

on oxygen

Depth

feet/metres

Bottom

Time

(min)

Time to

1st Stop

80

24.3

70

21.3

60

18.2

50

15.2

40

12.1

30

9.1

Surface

Interval

50

15.2

40

12.1 Ascent

Total

deco. time

(min:sec)

10 4:20 4:20

30 3:20 3 5 10 12 10 49:20

40 3:20 3 5 10 21 10 63:20

50 3:00 2 3 5 10 29 10 73:20

60 3:00 2 5 5 10 37 10 83:20

70 3:00 2 7 5 10 45 10 98:20

80 3:00 6 10 5 10 51 10 111:20

130

39.6 90 3:00 10 14 5 10 56 10 124:20










Time in chamber

on oxygen

Depth

feet/metres

Bottom

Time

(min)

Time to

1st Stop

80

24.3

70

21.3

60

18.2

50

15.2

40

12.1

30

9.1

Surface

Interval

50

15.2

40

12.1 Ascent

Total

deco. time

(min:sec)

10 4:40 4:40

25 3:40 3 5 10 11 10 48:40

30 3:40 3 5 10 15 10 52:40

35 3:40 3 5 10 20 10 62:40

40 3:20 2 3 5 10 24 10 64:40

45 3:20 2 4 5 10 29 10 69:40

50 3:20 2 6 5 10 33 10 76:40

55 3:20 2 7 5 10 38 10 81:40

60 3:20 2 9 5 10 43 10 93:40

65 3:20 4 11 5 10 48 10 107:40

140

42.6

70 3:00 2 7 13 5 10 51 10 117:40

5 5:00 5:00

25 4:00 3 5 10 13 10 51:00

30 4:00 3 5 10 18 10 56:00

35 3:40 2 4 5 10 23 10 69:00

40 3:40 5 7 5 10 27 10 72:00

45 3:40 6 9 5 10 33 10 82:00

50 3:20 2 7 11 5 10 38 10 103:00

150

45.7 55 3:00 2 5 9 14 5 10 44 10 119:00

5 5:20 5:20

20 4:20 3 5 10 11 10 49:20

25 4:20 3 5 10 16 10 54:20

30 4:00 2 4 5 10 21 10 67:20

35 4:00 4 7 5 10 26 10 70:20

40 3:40 3 6 9 5 10 32 10 84:20

160

48.7 45 3:20 3 4 8 12 5 10 38 10 105:20






Time in chamber

on oxygen

Depth

feet/metres

Bottom

Time

(min)

Time to

1st Stop

80

24.3

70

21.3

60

18.2

50

15.2

40

12.1

30

9.1

Surface

Interval

50

15.2

40

12.1 Ascent

Total

deco. time

(min:sec)

5 5:40 5:40

20 4:40 3 5 10 13 10 51:40

25 4:40 3 5 10 19 10 57:40

30 4:20 5 7 5 10 23 10 75:40

35 4:00 4 6 9 5 10 29 10 81:40

170

51.5 40 3:40 4 4 8 13 5 10 36 10 105:40








Time in chamber

on oxygen

Depth

feet/metres

Bottom

Time

(min)

Time to

1st Stop

80

24.3

70

21.3

60

18.2

50

15.2

40

12.1

30

9.1

Surface

Interval

50

15.2

40

12.1 Ascent

Total

deco. time

(min:sec)

15 4:40 4 6 5 10 20 10 71:00

30 4:00 2 3 5 10 5 10 40 10 106:00 180 45 3:20 2 4 6 12 18 5 10 50 10 138:00

15 4:40 2 4 6 5 10 20 10 73:20

30 4:20 3 5 8 12 5 10 50 10 124:20 190 45 3:40 2 5 10 18 26 5 10 60 10 172:20







2.5 SURFACE DECOMPRESSION USING AIR

The Surface Decompression Using Air Table (referred to as SurD Air) should be used for surface decompression following an air dive when;

• a recompression chamber has lost all oxygen supplies.

• the diver has suffered severe (i.e. convulsions) signs and symptoms of CNS oxygen toxicity.

When using the SurD Air table, all ascents are made at 30 fpm. This includes the ascent rate from the last water stop. The time spent on the surface should not exceed 3½ minutes and the rate of descent to the first recompression chamber stop should not exceed 60 fpm. The total elapsed time for these three procedures must not exceed 5 minutes.

If the prescribed surface interval is exceeded and the divers are asymptomatic, treat them using the USN Table 5 – See 2.6.4. If the divers are symptomatic, they are treated as if they have DCI (Treatment USN Table 6 – See 2.6.5) even if they are only displaying minor symptoms. Symptoms occurring during the chamber stops are treated as recurrences.



2.5.1 Table – Surface Decompression Using Air6

US Navy Air Surface Decompression Table

Time (min) at water

stops (feet/meters)

Chamber

stops

(air) (min)

(feet/meters)

Depth feet /

metres

Bottom

time

(min)

Time to

first stop

or

surface

(min:sec)

30

9.1

20

6.0

10

3.0

Surface

Interval

20

6.0

10

3.0

Total

deco. time

(min:sec)

230 1:00 3 5 7 15:20

250 1:00 3 5 11 19:20

270 1:00 3 5 15 23:20

40

12.1 300 1:00 3 5 19 27:20

120 1:20 3 5 5 13:40

140 1:20 3 5 10 18:40

160 1:20 3 5 21 29:40

180 1:20 3 5 29 37:40

200 1:20 3 5 35 43:40

220 1:20 3 5 40 48:40

50

15.2240 1:20 3 5 47 55:40

80 1:40 3 5 7 16:00

100 1:40 3 5 14 23:00

120 1:40 3 5 26 35:00

140 1:40 3 5 39 48:00

160 1:40 3 5 48 57:00

180 1:40 3 5 56 65:00

60

18.2200 1:20 3 5 3 69 81:30

60 2:00 3 5 8 17:20

70 70 2:00 3 5 14 23:20

6 Taken from the US Navy Manual, Chapter 9 , Table 9.10; 7 March 2000 (PDF Version 1.3)




Time (min) at water

stops (feet/meters)

Chamber

stops

(air) (min)

(feet/meters)

Depth feet /

metres

Bottom

time

(min)

Time to

first stop

or

surface

(min:sec)

30

9.1

20

6.0

10

3.0

Surface

Interval

20

6.0

10

3.0

Total

deco. time

(min:sec)

80 2:00 3 5 18 27:20

90 2:00 3 5 23 32:20

100 2:00 3 5 33 42:20

110 1:40 3 5 3 41 53:50

120 1:40 3 5 4 47 60:50

130 1:40 3 5 6 52 67:50

140 1:40 3 5 8 56 73:50

150 1:40 3 5 9 61 79:50

160 1:40 3 5 13 72 94:50

170 1:40 3 5 19 79 107:50




Time (min) at water

stops (feet/meters)

Chamber

stops

(air) (min)

(feet/meters)

Depth feet /

metres

Bottom

time

(min)

Time to

first stop

or

surface

(min:sec)

30

9.1

20

6.0

10

3.0

Surface

Interval

20

6.0

10

3.0

Total

deco. time

(min:sec)

50 2:23 3 5 10 19:40

60 2:20 3 5 17 26:40

70 2:20 3 5 23 32:40

80 2:00 3 5 3 31 44:10

90 2:00 3 5 7 39 56:10

100 2:00 3 5 11 46 67:10

110 2:00 3 5 13 53 76:10

120 2:00 3 5 17 56 83:10

130 2:00 3 5 19 63 92:10

140 2:00 26 5 26 69 128:10

150 2:00 32 5 32 77 148:10

80

24.3

40 2:40 3 5 7 17:00

50 2:40 3 5 18 28:00

60 2:40 3 5 25 35:00

70 2:20 3 5 7 30 47:30

80 2:20 13 5 13 40 73:30

90 2:20 18 5 18 48 91:30

100 2:20 21 5 21 54 103:30

110 2:20 24 5 24 61 116:30

120 2:20 32 5 32 68 139:30

90

27.4

130 2:00 5 36 5 36 74 158:30

10040 3:00 3 5 15 25:20




Time (min) at water

stops (feet/meters)

Chamber

stops

(air) (min)

(feet/meters)

Depth feet /

metres

Bottom

time

(min)

Time to

first stop

or

surface

(min:sec)

30

9.1

20

6.0

10

3.0

Surface

Interval

20

6.0

10

3.0

Total

deco. time

(min:sec)

50 2:40 3 5 3 24 37:50

60 2:40 3 5 9 28 47:50

70 2:40 3 5 17 39 66:50

80 2::40 23 5 23 48 101:50

40 2:20 3 23 5 23 57 113:50

100 2:20 7 23 5 23 66 126:50

110 2:20 10 34 5 34 72 157:50

120 2:20 12 41 5 41 78 179:50




Time (min) at water

stops (feet/meters)

Chamber

stops

(air) (min)

(feet/meters)

Depth feet /

metres

Bottom

time

(min)

Time to

first stop

or

surface

(min:sec)

30

9.1

20

6.0

10

3.0

Surface

Interval

20

6.0

10

3.0

Total

deco. time

(min:sec)

30 3:20 3 5 7 17:40

40 3:00 3 5 3 21 35:10

50 3:00 3 5 8 26 45:10

60 3:00 18 5 18 36 80:10

70 2:40 1 23 5 23 48 103:10

80 2:40 7 23 5 23 57 118:10

90 2:40 12 30 5 30 64 144:10

110

33.5

100 2:40 15 37 5 37 72 169:10




Time (min) at water stops

(feet/meters)

Chamber

stops

(air) (min)

(feet/meters)

Depth

feet/metres

Bottom

time

(min)

Time to

first stop

or

surface

(min:sec)

50

15.

2

40

12.

1

30

9.1

20

6.0

10

3.0

Surface

Interval

20

6.0

10

3.0

Total

deco.

time (min:sec)

25 3:40 3 5 6 17:00

30 3:40 3 5 14 25:00

40 3:20 3 5 5 25 41:30

50 3:20 15 5 15 31 69:30

60 3:00 2 22 5 22 45 99:30

70 3:00 9 23 5 23 55 118:30

80 3:00 15 27 5 27 63 140:30

90 3:00 19 37 5 37 74 175:30

120

35.5

100 3:00 23 45 5 45 80 201:30

25 4:00 3 5 10 21:20

30 3:40 3 5 3 18 32:50

40 3:40 10 5 10 25 53:50

50 3:20 3 21 5 21 37 90:50

60 3:20 9 23 5 23 52 115:50

70 3:20 16 24 5 24 61 133:50

80 3:00 3 19 35 5 35 72 172:50

130

39.6

90 3:00 8 19 45 5 45 80 205:50





(feet/meters)

Chamber

stops

(air) (min)

(feet/meters)

Depth

feet/metres

Bottom

time

(min)

Time to

first stop

or

surface

(min:sec)

50

15.

2

40

12.

1

30

9.1

20

6.0

10

3.0

Surface

Interval

20

6.0

10

3.0

Total

deco.

time (min:sec)

20 4:20 3 5 6 17:40

25 4:00 3 5 3 14 29:10

30 4:00 5 5 5 21 40:10

40 3:40 2 16 5 16 26 69:10

50 3:40 6 24 5 24 44 107:10

60 3:40 16 23 5 23 56 127:10

70 3:20 4 19 32 5 32 68 164:10

140

42.6

80 3:20 10 23 41 5 41 79 203:10

20 4:20 3 5 3 7 22:30

25 4:20 4 5 4 17 34:30

30 4:20 8 5 8 24 49:30

40 4:00 5 19 5 19 33 85:30

50 4:00 12 23 5 23 51 118:30

60 3:40 3 19 26 5 26 62 145:30

70 3:40 11 19 39 5 39 75 192:30

150

45.7

80 3:20 1 17 19 50 5 50 84 230:30

20 4:40 3 5 3 11 26:50

25 4:40 7 5 7 20 43:50

30 4:20 2 11 5 11 25 58:50

40 4:20 7 23 5 23 39 101:50

50 4:00 2 16 23 5 23 55 128:50

60 4:00 9 19 33 5 33 69 172:50

160

48.770 3:40 1 17 22 44 5 44 80 217:50





(feet/meters)

Chamber

stops

(air) (min)

(feet/meters)

Depth

feet/metres

Bottom

time

(min)

Time to

first stop

or

surface

(min:sec)

50

15.

2

40

12.

1

30

9.1

20

6.0

10

3.0

Surface

Interval

20

6.0

10

3.0

Total

deco.

time (min:sec)

15 5:00 3 5 3 5 21:10

20 5:00 4 5 4 15 33:10

25 4:40 2 7 5 7 23 49:10

30 4:40 4 13 5 13 26 66:10

40 4:20 1 10 23 5 23 45 112:10

50 4:20 5 18 23 5 23 61 140:10

60 4:00 2 15 22 37 5 37 74 197:10

170

51.8

70 4:00 8 17 19 51 5 51 86 242:10





(feet/meters)

Chamber

stops

(air) (min)

(feet/meters)

Depth

feet/metres

Bottom

time

(min)

Time to

first stop

or

surface

(min:sec)

50

15.

2

40

12.

1

30

9.1

20

6.0

10

3.0

Surface

Interval

20

6.0

10

3.0

Total

deco.

time (min:sec)

15 5:20 3 5 3 6 22:30

20 5:00 1 5 5 5 17 38:30

25 5:00 3 10 5 10 24 57:30

30 5:00 6 17 5 17 27 77:30

40 4:40 3 14 23 5 23 50 123:30

50 4:20 2 9 19 30 5 30 65 165:30

180

54.860 4:20 5 16 19 44 5 44 81 219:30

15 5:40 4 5 4 7 25:50

20 5:20 2 6 5 6 20 44:50

25 5:20 5 11 5 11 25 62:50

30 5:00 1 8 19 5 19 32 89:50

40 5:00 8 14 23 5 23 55 133:50

50 4:40 4 13 22 33 5 33 72 187:50

190

57.960 4:40 10 17 19 50 5 50 84 240:50



2.6 OMITTED DECOMPRESSION

Certain emergencies, such as uncontrolled ascents, an exhausted air supply, or bodily injury, may interrupt or prevent required decompression. If the diver shows symptoms of decompression sickness or arterial gas embolism, immediate treatment using the appropriate oxygen or air recompression treatment table is essential. Even if the diver shows no symptoms, omitted decompression must be addressed in some manner to avert later difficulty. The Table at 2.6.2 summarizes management of asymptomatic Omitted Decompression.

2.6.1 Planned and Unplanned Omitted Decompression

Omitted decompression may or may not be planned. Planned omitted decompression results when a condition develops at depth that will require the diver to surface before completing all of the decompression stops and when there is time to consider all available options, ready the recompression chamber, and alert all personnel as to the planned evolution.

Equipment malfunctions, diver injury, or sudden severe storms are examples of these situations. In unplanned omitted decompression, the diver suddenly appears at the surface without warning or misses decompression for some unforeseen reason. In either instance, the Surface Decompression Tables may be used to remove the diver from the water, if the surfacing time occurs such that water stops are either not required or have already been completed. When the conditions that permit using the Surface Decompression Tables are not fulfilled, the diver’s decompression will be compromised. Special care shall be taken to detect signs of decompression sickness. The diver must be returned to pressure as soon as possible.



2.6.2 Table – Management of Asymptomatic Decompression7

Action

Depth at which

Omission Began

Decompression

status

Eligible

for

SurD Surface Interval

Chamber

Available No Chamber Available

No

decompression

N/A N/A Observe on surface for 1 hour

Yes Less than 5

minutes

Use surface

decompression

tables

Perform Chamber stops in

water.

(See note 1.)

No Less than 1

minute

Return to depth of stop. Increase stop time 1

minute. Resume decompression. 20 FSW or

shallower

Decompression

stops required

No Greater than 1

minute

Return to depth of stop. Multiply 20- and 10-

foot stop times by 1.5.

OR: Treatment Table 5 if for surface interval

less than 5 minutes.

OR: Treatment Table 6 if for surface interval

less than 5 minutes.

No

decompression

N/A N/A Observe on surface for 1 hour

Decompression

stops required

YES Less than 5

minutes.

Use surface

decompression

tables

Perform Chamber stops in

water.

(See note 1.)

Decompression

stops required.

No

No

Less than 5

minutes

Greater than 5

minutes.

Treatment Table

5 (Note 2)

Treatment Table

6 (Note 2)

Deeper than 20

FSW

Decompression

stops Required

(Greater than 30

minutes)

No Any Treatment Table

6

Descend to depth of first

stop. Follow the schedule

to 30 FSW.

Multiply 30, 20 , 10 FSW

stops by 1.5.

NOTES:

1. Sur-D Air only.

2. If a diver missed a stop deeper than 60 feet and oxygen is available, first compress to the depth of the first missed

stop. Double this stop, then decompress to 60 feet using the appropriate decompression schedule doubling all

stop times. Decompress from 60 feet on Treatment Table 5 or 6 as appropriate.

3. Using a recompression chamber is strongly preferred over in-water recompression for returning a diver to

pressure.

4. Table 5 reference paragraph 2.6.4

5. Table 6 reference paragraph 2.6.5

7 Taken from the US Navy Manual, Chapter 21 , Table 21-3; 7 March 2000 (PDF Version 1.3)



2.6.3 Omitted Decompression Procedures

If the diver develops symptoms of decompression sickness during the surface interval, treat in accordance with the procedures in paragraph 2.6.5 (chamber available). If the diver has no symptoms of decompression sickness or arterial gas embolism, make up the omitted decompression as described in this section.

Ascent From 20 Feet or Shallower (Shallow Surfacing) with Decompression Stops Required

The diver surfaced from 20 feet or shallower, feels well, and can be returned to stop depth within 1 minute, the diver may complete normal decompression stops. The decompression stop from which ascent occurred is lengthened by 1 minute.

If the diver cannot be returned to the depth of the stop within 1 minute and the diver remains asymptomatic, return the diver to the stop from which the diver ascended. Multiply each decompression stop time missed by 1.5.

Alternatively, if the surface interval is less than 5 minutes, the diver may be placed in a recompression chamber and treated on a Treatment Table 5.

If the surface interval is greater than 5 minutes, the diver may be placed in a recompression chamber and treated on Treatment Table 6 (2.6.5). The diver should be observed for 1 hour after surfacing and/or completing treatment.

Ascent from 20 Feet or Shallower with No Decompression Stops Required

No recompression is required if the diver surfaces from 20 feet or shallower but was within no-decompression limits. The diver should be observed on the surface for 1 hour.

Ascent from Deeper than 20 Feet (Uncontrolled Ascent).

Any unexpected surfacing of the diver from depths in excess of 20 feet is considered a uncontrolled ascent.

If the diver is within no-decompression limits and asymptomatic, he should be observed for at least one hour on the surface. Recompression is not necessary unless symptoms develop.



Asymtomatic Uncontrolled Ascent.

Asymptomatic divers who experience an uncontrolled ascent and who have missed decompression stops are treated by recompression based on the amount of decompression missed as follows:

Oxygen Available. Immediately compress the diver to 60 feet in the recompression chamber. If less than 30 minutes of decompression (total ascent time from the tables) were missed, decompress from 60 feet on Treatment Table 5. see 2.6.4 If more than 30 minutes of decompression were missed, decompress from 60 feet on Treatment Table 6. see2.6.5

Development of Symptoms. As long as the diver shows no ill effects, decompress in accordance with the treatment table. Consider any decompression sickness that develops during or after this procedure to be a recurrence (any recurrence is to be reported to the DOF Subsea consulting physician to determine the next treatment required). Try to keep all surface intervals as short as possible (5 minutes or less). If an asymptomatic diver who has an uncontrolled ascent from a decompression dive has more than a 5-minute surface interval, recompress to 60 feet on Treatment Table 6 even if the missed decompression time was less than 30 minutes.

In-Water Procedure: When no recompression facility is available, use the following in-water procedure to make up omitted decompression in asymptomatic divers for ascents from depths below 20 feet. Recompress the diver in the water as soon as possible (preferably less than a 5-minute surface interval). Keep the diver at rest, provide a standby diver, and maintain good communication and depth control. Use the decompression schedule appropriate for the divers depth and bottom time. Follow the procedure below with 1 minute between stops:

• Return the diver to the depth of the first stop.

• Follow the schedule for stops 40-FSW and deeper.

• Multiply the 30-, 20-, and 10-FSW stops by 1.5.

Symptomatic Uncontrolled Ascent

If a diver has had an uncontrolled ascent and has any symptoms, he should be compressed immediately in a recompression chamber in accordance with Table 6.



2.6.4 USN Table 58

2.6.4.1 General Points

• Descent rate - 20 ft/min.

• Ascent rate - Not to exceed 1 ft/min. Do not compensate for slower ascent rates. Compensate for faster rates by halting the ascent.

• Time on oxygen begins on arrival at 60 feet. If oxygen breathing must be interrupted because of CNS.

• Oxygen Toxicity, allow 15 minutes after the reaction has entirely subsided and resume schedule at point of interruption.

• Treatment Table may be extended two oxygen-breathing periods at the 30-foot stop. No air break required between oxygen-breathing periods or prior to ascent.

• Tender breathes 100 percent O2 during ascent from the 30-foot stop to the surface. If the tender had a previous hyperbaric exposure in the previous 12 hours, an additional 20 minutes of oxygen breathing is required prior to ascent.

USN Table 5

8 Taken from the US Navy Manual, Chapter 21 , 7 March 2000 (PDF Version 1.3).



Tabulated Table 5

ACTION 3 DEPTH TIME GAS NOTES

LEAVE SURFACE

ON O2 0-60 feet 3.0 mins ON AIR Time from 0-60ft

not included

ARRIVE BOTTOM 60 feet 0 ON AIR

ON O2 60 feet 20 mins ON AIR

OFF O2 ON AIR 60 feet 5 mins ON AIR


ON O2 60-30 feet 30 mins ON AIR Ascent time @ 1ft/min




ON O2 30-0 feet 30 mins ON O2 Ascent time @ 1ft/min

Note

TOTAL TIME 135 mins

ELAPSED



2.6.5 USN Table 69

2.6.5.1 General Points

• Descent rate - 20 ft/min.

• Ascent rate - Not to exceed 1 ft/min. Do not compensate for slower ascent rates. Compensate for faster rates by halting the ascent.

• Time on oxygen begins on arrival at 60 feet.

• If oxygen breathing must be interrupted because of CNS Oxygen Toxicity, allow 15 minutes after the reaction has entirely subsided and resume schedule at point of interruption.

• Table 6 can be lengthened up to 2 additional 25-minute periods at 60 feet (20 minutes on oxygen and 5 minutes on air), or up to 2 additional 75-minute periods at 30 feet (15 minutes on air and 60 minutes on oxygen), or both.

• Tender breathes 100 percent O2 during the last 30 min. at 30 fsw and during ascent to the surface for an unmodified table or where there has been only a single extension at 30 or 60 feet. If there has been more than one extension, the O2 breathing at 30 feet is increased to 60 minutes. If the tender had a hyperbaric exposure within the past 12 hours an additional 60-minute O2 period is taken at 30 feet.

USN Table 6

9 Taken from the US Navy Manual, Chapter 21 , 7 March 2000 (PDF Version 1.3).



Tabulated Table 6

ACTION 3 DEPTH TIME GAS NOTES

LEAVE SURFACE

ON O2 0-60 feet 3.0 mins ON AIR Time from 0-60ft not included ARRIVE BOTTOM 60 feet 0 ON AIR ON O2 60 feet 20 mins ON AIR OFF O2 ON AIR 60 feet 5 mins ON AIR ON O2 60 feet 20 mins ON AIR OFF O2 ON AIR 60 feet 5 mins ON AIR ON O2 60 feet 20 mins ON AIR OFF O2 ON AIR 60 feet 5 mins ON AIR ON O2 60-30 feet 30 mins ON AIR Ascent time @ 1ft/min OFF O2 ON AIR 30 feet 15 mins ON AIR ON O2 30 feet 60 mins ON AIR OFF O2 ON AIR 30 feet 15 mins ON AIR ON O2 30 feet 60 mins ON AIR ON O2 30-0 feet 30 mins ON O2 Ascent time @ 1ft/min Note TOTAL TIME 285 mins ELAPSED



3.0 DIVING PROCEDURES – DCIEM DECOMPRESSION TABLES

3.1 INTRODUCTION

This section consists of parts of Appendix F of AS/NZS2299.1: 2007 Decompression Tables for Diving1. DOF Subsea has chosen the “DCIEM Decompression Tables For Diving” for use during air diving operations to 50 metres. DOF Subsea also uses the USN Air Decompression Tables for air diving operations when it is appropriate to do so.

The DOF Subsea Operations Manager will determine as part of the DPP plan and JHA, which tables are to be used for the specific diving operation being undertaken.

3.1.1.1 Warning

Under no circumstances shall US Navy and DCIEM Air Decompression Tables be used concurrently on the same diving task or within 24 hours of a previous diving task using one or the other table. Serious debilitating decompression illness can result from such practice as the tables were developed independently of each other using quite different procedures and principles. For example;

• Within a 24 hour period do not use the US Navy table for the first dive and then switch to the DCIEM tables for the second dive (or vice-a-versa).

• Do not complete a dive on day one using DCIEM Tables and the next day (day two, 20 hours later) undertake another dive using US Navy Tables.

3.1.2 Use Of Tables

It is important to note that while the depths referred to in the text of this Appendix are given in metres (m) followed by the corresponding imperial depths in feet (ft) in parentheses, these imperial depths are approximations only and are not interchangeable as far as the decompression requirements in the tables are concerned.

The depth segments in Tables 3.2.2 are divided into two sections by a limiting line. This limiting line corresponds to the line dividing the “Normal air range” and “Exceptional exposure range” in Figure F1 of AS/NZS2299.1: 2007. The shaded areas below each limiting line in the tables highlight dive profiles which are in the “Exceptional exposure range”.

Repetitive groups in Tables 3.2.2 are shown for dives within the “Normal air range” only, and are not shown for dives within the “Exceptional exposure range”, since repetitive diving is not recommended in this range.

Although these procedures cover diving only to a depth of 50 m (164 ft), decompression schedules for depths up to 72 m (240 ft) have been included to allow for altitude corrections.

3.1.3 Definitions

1 Taken from the Appendix F of AS/NZS2299.1: 2007 DCIEM Decompression Tables for Diving.



The tables in this Annexe may only be used in accordance with the following definitions.

NOTE: Supervisors need to be aware that some variations exists in definitions between US Navy and DCIEM Tables i.e. stop times.

Term Description

Ascent rate a specified rate of travel that the diver has to maintain up to and between decompression stops. For these tables, the ascent rate is from 18 ±3 m/min (from 60 ±10 ft/min).

Bottom time (BT) the total elapsed time from when a diver leaves the surface to the time (next whole minute) at which ascent is commenced, measured in minutes.

Decompression schedule a specific decompression procedure for a given combination of depth and bottom time as listed in a decompression table; it is normally described as maximum depth (metres (m) or feet (ft)) / bottom time (min).

Decompression stop a specific length of time that a diver has to spend at a specified depth to allow for the elimination of sufficient inert gas from the body to allow safe ascent to the next decompression stop or the surface.

Depth the maximum depth attained, measured in metres (m) or feet (ft).

Descent rate the maximum rate of travel allowed in descending to the bottom. For these tables, the descent rate is 18 m (60 ft)/min maximum.

Effective bottom time (EBT)

for repetitive diving, the calculated bottom time for decompression purposes taking into consideration the residual nitrogen from the previous dive(s).

Effective depth (ED) for a dive at altitude, the depth of an equivalent dive at sea level.

No-decompression (No-D) limit

the maximum bottom time that allows a direct ascent to the surface without requiring decompression stops.

Point of interruption the time at which normal decompression was interrupted as a result of an emergency procedure, i.e., loss of breathing air, O2 symptom. Once the situation allows the return to normal decompression procedures, the table is to be re-entered where the interruption occurred.

Repetitive dive any dive that has a repetitive factor greater than 1.0.

Repetitive factor (RF) a figure, used for repetitive diving, determined by the repetitive group and the length of the surface interval after a dive.



Repetitive group (RG) a letter that relates directly to the amount of residual nitrogen in a diver’s body immediately on surfacing from a dive.

Residual nitrogen nitrogen in excess of normal conditions, and which is still dissolved in a diver’s tissues after the surface has been reached.

Stop time the tabulated decompression stop time, which includes the travelling time to that stop at 18 ±3 m/min (60 ±10 ft/min).

Surface interval (SI) the time that a diver has spent on the surface following a dive; beginning as soon as the diver surfaces and ending as soon as the diver starts the descent for the next dive.

Surface interval — Sur D O2

when using Table 3.3.3 (Surface decompression with oxygen—Sur D O2 ), this is the time from the diver leaving the 9 m (30 ft) water stop (or the bottom if no stop required) to arriving at the 12 m (40 ft) compression chamber stop. The maximum time allowed is 7 min.



3.2 STANDARD AIR DECOMPRESSION (DECOMPRESSION IN THE WATER)

The Standard Air Decompression tables are contained in the Table at 3.2.2. Users of these tables are cautioned that they have only been validated by manned experiments to the limit of the “Normal air range”.

Note* When selecting DCIEM tables there is a variation in times between metres of sea water and feet of sea water.

3.2.1 Procedure

The procedure for Standard Air Decompression is as follows:

• Descend at 18 m/min (60 ft/min) or slower.

• Ascend at 18 ±3 m/min (60 ±10 ft/min) to the indicated stops and remain at each stop for the stop time. (The tabulated stop time for each stop includes the ascent time to that stop at 18 m/min [60 ft/min].)

Example:

Determine the decompression schedule required for a dive to 32 m (104 ft) and a bottom time of 22 min.

Procedure:

• Enter Table 3.2.2. at the depth that is exactly equal to or next greater than 32 m (104 ft). Select 33 m (110 ft).

• Using the 33 m (110 ft) schedule, proceed to the “Bottom time” column and find the listed time that is exactly equal to or next greater than 22 min. Select 25 min.

• Proceed horizontally across the table at the 33 m (110 ft)/25 min level to find the decompression stops and the ‘Repetitive group’ (RG) designator prescribed for this dive, as follows:

• 6 min stop at 6 m (20 ft)

• 10 min stop at 3 m (10 ft)

• ‘Repetitive group’ on surfacing — G



3.2.2 Standard Air Decompression Table (Metres)

DCIEM Air Decompression Table Stop Times (min) at different depths, m (ft) Depth

m (ft)

Bottom time 30 (100)

27 (90)

24 (80)

21 (70)

18 (60)

15 (50)

12 (40)

9 (30)

6 (20)

3 (10)

Decomp.Time. (min)

Repet. group

30 - - - - - - - - - - 1 A 60 - - - - - - - - - - 1 B 90 - - - - - - - - - - 1 C

120 - - - - - - - - - - 1 D 150 - - - - - - - - - - 1 E 180 - - - - - - - - - - 1 F 240 - - - - - - - - - - 1 G 300 - - - - - - - - - - 1 H 360 - - - - - - - - - - 1 I 420 - - - - - - - - - - 1 J 480 - - - - - - - - - - 1 K 600 - - - - - - - - - - 1 L

6 (20)

720 - - - - - - - - - - 1 M 30 - - - - - - - - - - 1 A 60 - - - - - - - - - - 1 C 90 - - - - - - - - - - 1 D

120 - - - - - - - - - - 1 F 150 - - - - - - - - - - 1 G 180 - - - - - - - - - - 1 H 210 - - - - - - - - - - 1 J 240 - - - - - - - - - - 1 K 270 - - - - - - - - - - 1 L 300 - - - - - - - - - - 1 M 330 - - - - - - - - - 3 3 N 360 - - - - - - - - - 5 5 O

400 - - - - - - - - - 7 7 420 - - - - - - - - - 10 10 450 - - - - - - - - - 15 15

9 (30)

480 - - - - - - - - - 20 20 20 - - - - - - - - - - 1 A 30 - - - - - - - - - - 1 B 60 - - - - - - - - - - 1 D 90 - - - - - - - - - - 1 G

120 - - - - - - - - - - 1 H 150 - - - - - - - - - - 1 J 180 - - - - - - - - - 5 5 M

200 - - - - - - - - - 10 10 210 - - - - - - - - - 15 15 220 - - - - - - - - - 19 19 240 - - - - - - - - - 26 26 270 - - - - - - - - - 35 35 300 - - - - - - - - - 44 44 330 - - - - - - - - - 53 53

12 (40)

360 - - - - - - - - - 62 62




m (ft)


27 (90)

24 (80)

21 (70)

18 (60)

15 (50)

12 (40)

9 (30)

6 (20)

3 (10)

Decomp.Time. (min)

Repet. group

10 - - - - - - - - - - 1 A 20 - - - - - - - - - - 1 B 30 - - - - - - - - - - 1 C 40 - - - - - - - - - - 1 D 50 - - - - - - - - - - 1 E 60 - - - - - - - - - - 1 F 75 - - - - - - - - - - 1 G

100 - - - - - - - - - 5 5 I 120 - - - - - - - - - 10 10 K 125 - - - - - - - - - 13 13 K 130 - - - - - - - - - 16 16 L 140 - - - - - - - - - 21 21 M

150 - - - - - - - - - 26 26 160 - - - - - - - - - 31 31 170 - - - - - - - - - 35 35 180 - - - - - - - - - 40 40 200 - - - - - - - - - 50 50 220 - - - - - - - - - 59 59 240 - - - - - - - - - 70 70 260 - - - - - - - - - 81 81

15 (50)

280 - - - - - - - - - 91 91 10 - - - - - - - - - - 1 A 20 - - - - - - - - - - 1 B 30 - - - - - - - - - - 1 D 40 - - - - - - - - - - 1 E 50 - - - - - - - - - - 1 F 60 - - - - - - - - - 5 5 G 80 - - - - - - - - - 10 10 I 90 - - - - - - - - - 16 16 J

100 - - - - - - - - - 24 24 K 110 - - - - - - - - - 30 30 L 120 - - - - - - - - - 36 36 M

130 - - - - - - - - 2 40 42 140 - - - - - - - - 2 46 48 150 - - - - - - - - 3 52 55 160 - - - - - - - - 3 59 62 170 - - - - - - - - 4 65 69 180 - - - - - - - - 4 73 77 190 5 80 85 200 - - - - - - - - 7 87 94 210 - - - - - - - - 13 91 104 220 - - - - - - - - 17 97 114 230 - - - - - - - - 21 103 124

18 (60)

240 - - - - - - - - 24 109 133




m (ft)


27 (90)

24 (80)

21 (70)

18 (60)

15 (50)

12 (40)

9 (30)

6 (20)

3 (10)

Decomp.Time. (min)

Repet. group

10 - - - - - - - - - - 1 A 20 - - - - - - - - - - 1 C 25 - - - - - - - - - - 1 D 30 - - - - - - - - - - 1 D 35 - - - - - - - - - - 1 E 40 - - - - - - - - - 5 5 F 50 - - - - - - - - - 10 10 G 60 - - - - - - - - - 12 12 H 70 - - - - - - - - 3 17 20 J 80 - - - - - - - - 4 25 29 K 90 - - - - - - - - 5 32 37 M

100 - - - - - - - - 6 39 45 N

110 - - - - - - - - 7 46 53 120 - - - - - - - - 7 54 61 130 - - - - - - - - 8 62 70 140 - - - - - - - - 9 71 80 150 - - - - - - - - 15 77 92 160 - - - - - - - - 20 85 105 170 - - - - - - - - 25 93 118 180 - - - - - - - - 29 101 130 190 - - - - - - - - 34 109 143

21 (70)

200 - - - - - - - - 38 117 155 10 - - - - - - - - - - 2 A 15 - - - - - - - - - - 2 C 20 - - - - - - - - - - 2 D 25 - - - - - - - - - - 2 E 30 - - - - - - - - - 5 5 F 40 - - - - - - - - - 11 11 G 50 - - - - - - - - 4 11 15 H 55 - - - - - - - - 5 15 20 I 60 - - - - - - - - 6 21 27 J 65 - - - - - - - - 7 25 32 J 70 - - - - - - - - 7 30 37 K 75 - - - - - - - - 8 34 42 L 80 - - - - - - - - 9 37 46 M

85 - - - - - - - - 9 42 51 90 - - - - - - - - 10 46 56 95 - - - - - - - - 11 50 61

100 - - - - - - - - 11 55 66 110 - - - - - - - 2 12 64 78 120 - - - - - - - 3 18 72 93 130 - - - - - - - 4 23 82 109 140 - - - - - - - 4 28 93 125 150 - - - - - - - 5 33 104 142

24 (80)

160 - - - - - - - 5 39 114 158




m (ft)


27 (90)

24 (80)

21 (70)

18 (60)

15 (50)

12 (40)

9 (30)

6 (20)

3 (10)

Decomp.Time. (min)

Repet. group

5 - - - - - - - - - - 2 A 10 - - - - - - - - - - 2 B 15 - - - - - - - - - - 2 C 20 - - - - - - - - - - 2 D 25 - - - - - - - - - 7 7 E 30 - - - - - - - - 2 9 11 F 40 - - - - - - - - 6 10 16 H 45 - - - - - - - - 7 14 21 I 50 - - - - - - - - 8 20 28 J 55 - - - - - - - - 9 26 35 K 60 - - - - - - - 2 8 31 41 L

65 - - - - - - - 3 8 36 47 70 - - - - - - - 3 9 40 52 75 - - - - - - - 4 9 46 59 80 - - - - - - - 4 10 51 65 85 - - - - - - - 5 10 56 71 90 - - - - - - - 5 14 60 79 95 - - - - - - - 6 17 64 87

100 - - - - - - - 6 20 70 96 110 - - - - - - - 7 26 82 115

27 (90)

120 - - - - - - - 8 31 95 134 5 - - - - - - - - - - 2 A

10 - - - - - - - - - - 2 B 15 - - - - - - - - - - 2 D 20 - - - - - - - - - 8 8 E 25 - - - - - - - - 3 9 12 F 30 - - - - - - - - 5 10 15 G 35 - - - - - - - - 7 11 18 H 40 - - - - - - - - 9 16 25 I 45 - - - - - - - 3 8 23 34 J 50 - - - - - - - 4 8 29 41 K 55 - - - - - - - 5 9 34 48 L

60 - - - - - - - 6 9 40 55 65 - - - - - - - 6 10 46 62 70 - - - - - - - 7 10 52 69 75 - - - - - - - 8 14 56 78 80 - - - - - - - 8 18 61 87 85 - - - - - - - 9 21 67 97 90 - - - - - - 2 8 24 75 109 95 - - - - - - 3 8 27 82 120

100 - - - - - - 3 8 31 90 132 105 - - - - - - 3 9 34 98 144

30 (100)

110 - - - - - - 4 8 38 106 156




m (ft)


27 (90)

24 (80)

21 (70)

18 (60)

15 (50)

12 (40)

9 (30)

6 (20)

3 (10)

Decomp.Time. (min)

Repet. group

5 - - - - - - - - - - 2 A 10 - - - - - - - - - - 2 B 12 - - - - - - - - - - 2 C 15 - - - - - - - - - 5 5 D 20 - - - - - - - - 3 9 12 F 25 - - - - - - - - 6 10 16 G 30 - - - - - - - - 9 10 19 H 35 - - - - - - - 3 8 16 27 I 40 - - - - - - - 5 8 24 37 J 45 - - - - - - - 6 9 31 46 K 50 - - - - - - - 7 9 38 54 M 55 - - - - - - - 8 10 44 62 N

60 - - - - - - 2 7 10 51 70 65 - - - - - - 3 7 15 55 80 70 - - - - - - 4 7 19 62 92 75 - - - - - - 4 8 23 68 103 80 - - - - - - 5 8 26 77 116 85 - - - - - - 5 9 30 86 130 90 - - - - - - 6 9 34 95 144 95 - - - - - - 6 9 38 105 158

100 - - - - - - 7 9 42 114 172 105 - - - - - - 7 12 45 123 187

33 (110)

110 - - - - - - 8 15 48 130 201 5 - - - - - - - - - - 2 A

10 - - - - - - - - - - 2 C 15 - - - - - - - - - 10 10 D 20 - - - - - - - - 6 9 15 F 25 - - - - - - - - 9 10 19 G 30 - - - - - - - 4 8 14 26 I 35 - - - - - - - 6 8 24 38 J 40 - - - - - - - 8 8 32 48 K 45 - - - - - - 3 6 10 38 57 M 50 - - - - - - 4 7 10 46 67 N

55 - - - - - - 5 7 13 53 78 60 - - - - - - 6 7 18 59 90 65 - - - - - - 6 8 22 66 102 70 - - - - - - 7 8 27 75 117 75 - - - - - - 8 8 31 86 133 80 - - - - - 2 6 9 35 97 149 85 - - - - - 3 6 10 40 107 166 90 - - - - - 3 7 13 42 118 183 95 - - - - - 4 6 16 46 128 200

36 (120)

100 - - - - - 4 7 19 50 136 216




m (ft)


27 (90)

24 (80)

21 (70)

18 (60)

15 (50)

12 (40)

9 (30)

6 (20)

3 (10)

Decomp.Time. (min)

Repet. group

5 - - - - - - - - - - 2 A 8 - - - - - - - - - - 2 B

10 - - - - - - - - - 5 5 C 15 - - - - - - - - 4 8 12 E 20 - - - - - - - - 8 10 18 G 25 - - - - - - - 5 7 11 23 H 30 - - - - - - - 7 8 22 37 J 35 - - - - - - 3 6 9 30 48 K 40 - - - - - - 4 7 9 39 59 M 45 - - - - - - 6 7 10 47 70 N

50 - - - - - - 7 7 15 53 82 55 - - - - - 2 6 8 20 61 97 60 - - - - - 3 6 8 25 70 112 65 - - - - - 4 6 8 30 82 130 70 - - - - - 4 7 9 34 94 148 75 - - - - - 5 6 11 39 106 167 80 - - - - - 5 7 14 42 118 186 85 - - - - - 6 7 17 47 129 206

39 (130)

90 - - - - - 6 8 20 52 138 224 7 - - - - - - - - - - 2 B

10 - - - - - - - - - 7 7 D 15 - - - - - - - - 6 9 15 F 20 - - - - - - - 4 7 10 21 G 25 - - - - - - - 7 8 17 32 I 30 - - - - - - 4 6 8 28 46 K 35 - - - - - - 5 7 9 37 58 L 40 - - - - - - 7 7 10 46 70 N 45 - - - - - 3 5 8 16 53 85 O

50 - - - - - 4 6 8 21 62 101 55 - - - - - 5 6 8 27 73 119 60 - - - - - 6 6 9 32 86 139 65 - - - - - 6 7 10 37 99 159 70 - - - - - 7 7 14 40 114 182 75 - - - - 3 5 7 18 45 126 204 80 - - - - 3 6 7 21 51 137 225 85 - - - - 4 5 8 25 57 146 245

42 (140)

90 - - 4 6 8 28 65 152 263




m (ft)


27 (90)

24 (80)

21 (70)

18 (60)

15 (50)

12 (40)

9 (30)

6 (20)

3 (10)

Decomp.Time. (min)

Repet. group

7 - - - - - - - - - - 3 B 10 - - - - - - - - - 9 9 D 15 - - - - - - - - 8 9 17 F 20 - - - - - - - 6 7 11 24 H 25 - - - - - - 4 5 8 23 40 J 30 - - - - - - 6 6 9 34 55 K 35 - - - - - 3 5 7 10 44 69 M 40 - - - - - 4 6 7 15 52 84 O

45 - - - - - 5 6 8 21 61 101 50 - - - - - 6 7 8 27 73 121 55 - - - - 3 5 6 9 33 88 144 60 - - - - 3 5 7 12 38 103 168 65 - - - - 4 5 8 16 42 119 194 70 - - - - 5 5 8 20 48 132 218 75 - - - - 5 6 8 24 55 142 240

45 (150)

80 - - - - 6 6 8 28 63 150 261 6 - - - - - - - - - - 3 B

10 - - - - - - - - - 11 11 D 15 - - - - - - - 4 6 10 20 G 20 - - - - - - - 8 8 14 30 H 25 - - - - - - 6 6 8 29 49 K 30 - - - - - 3 5 7 9 40 64 M 35 - - - - - 5 5 8 13 49 80 N

40 - - - - - 6 6 8 20 59 99 45 - - - - 3 5 6 9 26 72 121 50 - - - - 4 5 7 9 33 88 146 55 - - - - 5 5 7 13 38 105 173 60 - - - - 6 5 8 17 43 122 201 65 - - - - 7 5 8 22 50 135 227

48 (160)

70 - - - 3 4 6 8 26 58 146 251 6 - - - - - - - - - - 3 B

10 - - - - - - - - 5 8 13 D 15 - - - - - - - 5 7 10 22 G 20 - - - - - - 5 5 8 20 38 I 25 - - - - - 3 5 6 9 33 56 K 30 - - - - - 5 5 7 10 46 73 M 35 - - - - 3 4 6 8 18 55 94 O

40 - - - - 4 5 6 8 26 68 117 45 - - - - 5 5 7 9 32 85 143 50 - - - - 6 6 7 13 37 105 174 55 - - - 3 4 6 7 18 44 122 204 60 - - - 4 4 6 8 23 51 137 233 65 - - - 5 4 6 9 27 61 148 260

51 (170)

70 - - - 5 5 6 12 30 72 155 285




m (ft)


27 (90)

24 (80)

21 (70)

18 (60)

15 (50)

12 (40)

9 (30)

6 (20)

3 (10)

Decomp.Time. (min)

Repet. group

5 - - - - - - - - - - 3 B 10 - - - - - - - - 6 9 15 E 15 - - - - - - - 7 7 11 25 H 20 - - - - - - 6 6 8 25 45 J 25 - - - - - 5 5 7 9 39 65 M 30 - - - - 3 4 6 7 15 50 85 O

35 - - - - 5 4 6 8 23 62 108 40 - - - - 6 5 7 9 30 80 137 45 - - - 4 4 5 7 13 36 101 170 50 - - - 4 5 5 8 18 42 121 203 55 - - - 5 5 6 8 23 51 137 235

54 (180)

60 - - - 6 5 6 9 28 61 149 264 5 - - - - - - - - - - 3

10 - - - - - - - - 8 9 17 15 - - - - - - 4 5 7 11 27 20 - - - - - 4 4 6 9 29 52 25 - - - - - 7 5 7 10 44 73 30 - - - - 5 7 6 8 19 55 97 35 - - - 3 4 5 6 9 27 72 126 40 - - - 4 4 5 7 11 35 93 159 45 - - - 5 5 5 8 17 41 116 197 50 - - 3 3 5 6 8 22 50 135 232

57 (190)

55 - - 4 3 5 7 9 27 61 149 265 5 - - - - - - - - - - 4

10 - - - - - - - - 10 9 19 15 - - - - - - 5 6 8 16 35 20 - - - - - 5 5 6 10 33 59 25 - - - - 5 4 5 7 14 48 83 30 - - - 3 4 4 6 9 23 62 111 35 - - - 5 4 5 6 10 32 84 146 40 - - - 6 4 6 7 15 38 109 185 45 - - 4 3 5 6 8 21 47 131 225

60 (200)

50 - - 5 4 4 7 9 27 58 147 261 5 - - - - - - - - - 5 5

10 - - - - - - - 5 6 10 21 15 - - - - - - 7 6 8 20 41 20 - - - - - 7 5 7 9 39 67 25 - - - - 6 4 6 8 17 52 93 30 - - - 5 4 4 7 8 28 71 127 35 - - 3 3 4 6 7 12 35 97 167 40 - - 4 4 4 6 8 19 43 123 211 45 - - 5 4 5 6 9 25 54 142 250

63 (210)

50 - 3 3 4 6 6 13 29 70 154 288




m (ft)


27 (90)

24 (80)

21 (70)

18 (60)

15 (50)

12 (40)

9 (30)

6 (20)

3 (10)

Decomp.Time. (min)

Repet. group

5 - - - - - - - - - 7 7 10 - - - - - - - 7 6 10 23

156 - - - - - 4 5 5 9 24 47 20 - - - - 5 4 5 7 10 43 74 25 - - - 4 4 4 6 8 21 58 105 30 - - 3 3 4 5 7 9 32 81 144 35 - - 5 3 4 6 7 16 39 110 190 40 - 3 3 4 4 7 8 23 49 135 236

66

(220)

45 - 4 3 4 5 7 11 28 65 151 278 5 - - - - - - - - - 8 8

10 - - - - - - - 8 7 10 25 15 - - - - - 6 4 6 9 28 53 20 - - - - 6 4 6 7 12 47 82 25 - - - 6 3 5 6 9 24 65 118 30 - - 5 3 4 5 7 12 35 93 164 35 - 3 3 4 4 6 8 19 44 123 214

69 (230)

40 - 5 3 4 5 6 9 27 57 146 262 5 - - - - - - - - - 9 9

10 - - - - - - 4 5 7 11 27 15 - - - - - 7 5 6 9 32 59 20 - - - 4 4 4 5 8 16 50 91 25 - - 4 3 4 5 6 9 28 73 132 30 - - 6 3 5 5 8 15 37 106 185 35 - 5 3 4 4 6 9 23 49 135 238

72 (240)

40 3 3 3 4 6 6 13 28 67 153 286



3.3 SURFACE DECOMPRESSION WITH OXYGEN (SUR D O2 )

The Surface Decompression with Oxygen (Sur D O2 ) tables are contained in the Table at 3.3.3. These tables have only been validated by manned experiments to the limits of the “exceptional exposure range”.

3.3.1 Procedure

The procedure for surface decompression with oxygen (Sur D O2) is as follows:

1 Ascend and decompress normally (see 3.2) to the 9 m (30 ft) stop (or to the surface if no in-water stop is shown).

2 Remain at the 9 m (30 ft) stop for the stop time (remembering that the stop time includes ascent to the 9 m (30 ft) stop at 18 ±3 m/min (60 ±10 ft/min).

3 Ascend to the surface and recompress on O2 to 12 m (40 ft) in the compression chamber; the surface interval — Sur D O2 (see below.) must not exceed 7 min.

NOTE: The maximum surface interval, Sur D O2 , of 7 min was chosen to enhance the operability of the procedure and to reduce the chances of omitted decompression during operations. Extensive experimentation using the full 7 min has proven this procedure safe. In operational use, the surface interval, Sur D O2, should be kept to a minimum. The surface Interval is the time from the diver leaving the 9mtr (30ft) water stop, or the bottom if no water stop required, to arriving at the 12 mtr (40ft) recompression chamber stop.

4 Remain on O2 at 12 m (40 ft) for the tabulated stop time with 5 min air breaks after every 30 min on O2

NOTE: The asterisks following the stop times for “Chamber on O2” in Table 3.3.3 represent the number of air breaks. The tabulated 12 m (40 ft) stop times are for O2 only, while the “Total decompression time” column includes the air breaks. If no asterisk follows a tabulated 30 min “Chamber on O2” stop time, no air break is taken prior to ascent on O2. If only one asterisk follows a tabulated 60 min “Chamber on O2” stop time, no second air break is taken prior to ascent on O2

5 Ascend to the surface on O2

6 NOTE: A time of 1 min for this “ascent” has been added to the “Total decompression time” column as an example only.



Example:

Determine the decompression schedule for a dive to 36 m (120 ft) with a duration of 75 min.

Procedure:

1 Enter Table 3.3.3 at the depth that is exactly equal to or next greater than 36 m (120 ft).

Select 36 m (120 ft).

2 Using the 36 m (120 ft) schedule, proceed to the “Bottom time” column and find the listed time which is exactly equal to or next greater than 75 min

Select 75 min.

3 Proceed horizontally across the table at the 36 m (120 ft)/75 min level to find the decompression stops and stop times as follows

Table 3.3.3 calls for

9 min stop at 12 m 8 min stop at 9 m Time from 9 m in-water to

12 m compression chamber stop on surface is maximum 7 min

80 min stop at 12 m on O2 (70min +2 × 5 min air

breaks)

No repetitive group (exceptional exposure dive)

NOTE: Repetitive diving can also be conducted using Sur D O2, as shown by repetitive groups in Tables 3.4.8 and 3.4.9for dives within the “Normal air range”, however these Repetitive groups may be different from those in Tables 3.2.2 and 3.3.3.

Supervisors are not to plan repetitive dives.



3.3.2 Oxygen related problems during Sur D O2

3.3.2.1 LOSS OF O2

For loss of O2, switch diver to standard air decompression (Table 3.2.2) and commence decompression at the 12 m (40 ft) stop.

NOTE: Previous O2 time is “good” time and is subtracted from 12 m (40 ft), 9 m (30 ft), 6 m (20 ft) and 3 m (10 ft) stops as appropriate.

Example:

Dive 42 m (140 ft), Bottom time 30 min: Table 3.3.3 call for 30 min Sur D O2.

Situation:

After 24 min on O2 in compression chamber, O2 is lost

At 42 m, Table 3.2.3 calls for

• 12 m — 4 min stop • 9 m — 5 min stop • 6 m — 8 min stop • 3 m — 28 min stop

The 24 min spent on O2 satisfied the 12 m, 9 m and 6 m stops, and 6 min of the 3 m stop; therefore, ascend to 3 m and complete decompression by remaining on air at 3 m for 22 min.



3.3.2.2 MINOR SYMPTOMS OF O2 TOXICITY

For minor symptoms of O2 toxicity, the procedure is as follows:

1 Take diver off O2

2 After symptoms have gone, either

• leave diver on air for an additional 15 min and then resume O2 from the time of interruption; or

• switch diver to the Standard Air Decompression Table 3.2.2 and complete decompression on air.

3 If O2 breathing is resumed and O2 symptoms recur, switch the diver to the Standard Air Decompression Table 3.2.2 and complete the decompression on air.

Example:

Dive 36 m (120 ft), Bottom time 75 min: Table 3.3.4 call for 70 min Sur D O2 plus two 5 min air breaks.

Situation:

After 11 min on O2 in compression chamber, diver develops symptoms of O2 toxicity.

Procedure:

• Take diver off O2. • Wait until diver stabilizes, then wait further 15 min. • Resume O2 breathing from point of interruption (see Note).

NOTE: If diver took 4 min to stabilize, then the 12 m (40 ft) compression chamber stop would be 11 + 4 (stabilize) + 15 (wait) + 19 (remainder of first O2 period) + 5 (air break) + 30 (second O2 period) + 5 (air break) + 10 (remaining O2 required) = 99 min.

In this case, however, the 10 (remaining O2 required) may be added to the 19 (remainder of first O2 period) thus precluding the need for the final 5 min air break. The 12 m (40 ft) compression stop would then become 11 + 4 (stabilize) + 15 (wait) + 29 (first O2 period) + 5 (air break) + 30 (second O2 period) = 94 min.

Further, since treatment may resume with 30 min O2 periods, it may be convenient, in some cases, to complete the treatment with the shortest O2 period. In this case, this would simply mean that the first O2 period would become 30 min, and the second O2 period 29 min.

3.3.2.3 Serious, incapacitating symptoms of central nervous system (CNS) O2 toxicity

For serious, incapacitating symptoms of CNS O2 toxicity, the procedure is as follows:

1 Take diver off O2 and stabilize.

2 Switch to Standard Air Decompression Table 3.2.2 and complete decompression on air.



3.3.3 Surface Decompression Using Oxygen

DCIEM Surface Decompression Using Oxygen Table

Stop time (min) at different depths, m

(ft) Depth

m

(ft) Bottom

time 30

(100)

27

(90)

24

(80)

21

(70)

18

(60)

15

(50)

12

(40)

9

(30)

Surface

Interval

Chamber

on O2

12m/(40ft)

Total

decomp.

time (min)

Repet.

group.

50 - - - - - - - - - 1 F

70 - - - - - - - - 10 18 H

80 - - - - - - - - 16 24 H

90 - - - - - - - - 20 28 I

100 - - - - - - - - 24 32 J

110 - - - - - - - - 28 36 K

120 - - - - - - - - 30 38 K

130 - - - - - - - - 32* 45

140 - - - - - - - - 38* 51

150 - - - - - - - - 42* 55

160 - - - - - - - - 46* 59

170 - - - - - - - - 50* 65

180 - - - - - - - - 54* 68

190 - - - - - - - - 57* 70

200 - - - - - - - - 60* 73

210 - - - - - - - - 63** 81

220 - - - - - - - - 69** 87

230 - - - - - - - - 73** 92

18

(60)

240 - - - - - - - -

MUST

NOT

EXCEE

D

7 min

77** 95

NOTE: Asterisk (*) indicates the number of 5 min air breaks





(ft) Depth

m

(ft) Bottom

time 30

(100)

27

(90)

24

(80)

21

(70)

18

(60)

15

(50)

12

(40)

9

(30)

Surface

Interval

Chamber

on O2

12m/(40ft)

Total

decomp.

time (min)

Repet.

group.

35 - - - - - - - - - 1 E

50 - - - - - - - - 6 14 H

60 - - - - - - - - 15 23 H

70 - - - - - - - - 21 29 I

80 - - - - - - - - 26 34 J

90 - - - - - - - - 30 38 K

100 - - - - - - - - 34* 47 K

110 - - - - - - - - 40* 53

120 - - - - - - - - 45* 58

130 - - - - - - - - 50* 63

140 - - - - - - - - 55* 68

150 - - - - - - - - 59* 72

160 - - - - - - - - 63** 81

170 - - - - - - - - 71** 89

180 - - - - - - - - 76** 94

190 - - - - - - - - 81** 99

21

(70)

200 - - - - - - - 1

MUST

NOT

EXCEE

D

7 min

85** 104

25 - - - - - - - - - 2 E

45 - - - - - - - - 12 20 H

50 - - - - - - - - 17 25 H

55 - - - - - - - - 21 29 H

60 - - - - - - - - 24 32 I

70 - - - - - - - - 30 38 J

80 - - - - - - - - 35* 48 K

90 - - - - - - - - 42* 55

100 - - - - - - - 2 47* 62

110 - - - - - - - 2 53* 68

120 - - - - - - - 3 58* 74

130 - - - - - - - 4 62** 84

140 - - - - - - - 4 72** 94

150 - - - - - - - 5 78** 101

24

(80)

160 - - - - - - - 5

MUST

NOT

EXCEE

D

7 min

84** 107





(ft) Depth

m

(ft) Bottom

time 30

(100)

27

(90)

24

(80)

21

(70)

18

(60)

15

(50)

12

(40)

9

(30)

Surface

Interval

Chamber

on O2

12m/(40ft)

Total

decomp.

time (min)

Repet.

group.

20 - - - - - - - - - 2 D

35 - - - - - - - - 8 16 G

40 - - - - - - - - 16 24 G

45 - - - - - - - - 21 29 H

50 - - - - - - - - 25 33 H

55 - - - - - - - 1 28 37 I

60 - - - - - - - 2 30* 45 J

70 - - - - - - - 3 37* 53

80 - - - - - - - 4 45* 62

90 - - - - - - - 5 52* 70

100 - - - - - - - 6 58* 77

110 - - - - - - - 7 65** 90

27

(90)

120 - - - - - - - 8

MUST

NOT

EXCEE

D

7 min

74** 100

15 - - - - - - - - - 2 D

30 - - - - - - - - 8 16 G

35 - - - - - - - - 17 25 G

40 - - - - - - - 2 22 32 H

45 - - - - - - - 3 27 38 I

50 - - - - - - - 4 30 42 I

55 - - - - - - - 5 31* 49 J

60 - - - - - - - 6 37* 56

70 - - - - - - - 7 46* 66

80 - - - - - - - 8 54* 75

90 - - - - - - 2 8 60* 83

100 - - - - - - 3 8 72** 101

30 (100)

110 - - - - - - 4 8

MUST

NOT

EXCEE

D

7 min

81** 111






(ft) Depth

m

(ft) Bottom

time 30

(100)

27

(90)

24

(80)

21

(70)

18

(60)

15

(50)

12

(40)

9

(30)

Surface

Interval

Chamber

on O2

12m/(40ft)

Total

decomp.

time (min)

Repet.

group.

12 - - - - - - - - - 2 C

25 - - - - - - - - 7 15 G

30 - - - - - - - 2 16 28 G

35 - - - - - - - 3 22 33 H

40 - - - - - - - 5 27 40 I

45 - - - - - - - 6 30* 49 J

50 - - - - - - - 7 35* 55 K

55 - - - - - - - 8 40* 61 K

60 - - - - - - 2 7 45* 67

65 - - - - - - 3 7 50* 73

70 - - - - - - 4 7 54* 78

75 - - - - - - 4 8 59* 84

80 - - - - - - 5 8 60** 91

85 - - - - - - 5 9 69** 101

90 - - - - - - 6 9 75** 108

95 - - - - - - 6 9 80** 113

100 - - - - - - 7 9 85** 119

105 - - - - - - 7 12 89** 126

33

(110)

110 - - - - - - 8 15

MUST

NOT

EXCEE

D

7 min

93*** 139






(ft) Depth

m

(ft) Bottom

time 30

(100)

27

(90)

24

(80)

21

(70)

18

(60)

15

(50)

12

(40)

9

(30)

Surface

Interval

Chamber

on O2

12m/(40ft)

Total

decomp.

time (min)

Repet.

group.

10 - - - - - - - - - 2 C

20 - - - - - - - - 7 15 F

25 - - - - - - - 2 13 23 G

30 - - - - - - - 4 21 33 G

35 - - - - - - - 6 27 41 H

40 - - - - - - - 8 30* 51 I

45 - - - - - - 3 6 36* 58 J

50 - - - - - - 4 7 42* 66 K

55 - - - - - - 5 7 48* 73

60 - - - - - - 6 7 53* 79

65 - - - - - - 6 8 58* 85

70 - - - - - - 7 8 60** 93

75 - - - - - - 8 8 70** 104

80 - - - - - 2 6 9 76** 111

85 - - - - - 3 6 10 82** 119

90 - - - - - 3 7 13 87** 128

95 - - - - - 4 6 16 90** 134

36 (120)

100 - - - - - 4 7 19

MUST

NOT

EXCEE

D

7 min

100*** 153

8 - - - - - - - - - 2 B

20 - - - - - - - - 8 16 G

25 - - - - - - - 5 18 31 G

30 - - - - - - - 7 26 41 H

35 - - - - - - 3 6 30* 52 I

40 - - - - - - 4 7 36* 60 J

45 - - - - - - 6 7 43* 69 K

50 - - - - - - 7 7 49* 76

55 - - - - - 2 6 8 54* 83

60 - - - - - 3 6 8 60* 90

65 - - - - - 4 6 8 67** 103

70 - - - - - 4 7 9 75** 113

75 - - - - - 5 6 11 81** 121

80 - - - - - 5 7 14 87** 131

85 - - - - - 6 7 17 90*** 143

39 (130)

90 - - - - - 6 8 20

MUST

NOT

EXCEE

D

7 min

101*** 158





(ft) Depth

m

(ft) Bottom

time 30

(100)

27

(90)

24

(80)

21

(70)

18

(60)

15

(50)

12

(40)

9

(30)

Surface

Interval

Chamber

on O2

12m/(40ft)

Total

decomp.

time (min)

Repet.

group.

7 - - - - - - - - - 3 B

15 - - - - - - - - 7 15 F

20 - - - - - - - 4 12 24 G

25 - - - - - - - 7 23 38 H

30 - - - - - - 4 6 30 48 I

35 - - - - - - 5 7 34* 59 J

40 - - - - - - 7 7 42* 69 K

45 - 3 5 8 49* 78 M

50 - - - - - 4 6 8 55* 86

55 - - - - - 5 6 8 60** 97

60 - - - - - 6 6 9 70** 109

65 - - - - - 6 7 10 78** 119

70 - - - - - 7 7 14 84** 130

75 - - - - 3 5 7 18 90** 141

80 - - - - 3 6 7 21 100*** 160

85 - - - - 4 5 8 25 107*** 172

42 (140)

90 4 6 8 28

MUST

NOT

EXCEE

D

7 min

113*** 182

7 - - - - - - - - - 3 B

15 - - - - - - - - 8 16 G

20 - - - - - - - 6 17 31 G

25 - - - - - - 4 5 27 44 H

30 - - - - - - 6 6 30* 55 I

35 - - - - - 3 5 7 40* 68 K

40 - - - - - 4 6 7 48* 78 M

45 - - - - - 5 6 8 55* 87

50 - - - - - 6 7 8 60** 99

55 - - - - 3 5 6 9 72** 113

60 - - - - 3 5 7 12 80** 125

65 - - - - 4 5 8 16 87** 138

70 - - - - 5 5 8 20 95*** 156

75 - - - - 5 6 8 24 105*** 171

45 (150)

80 - - - - 6 6 8 28

MUST

NOT

EXCEE

D

7 min

111*** 182





(ft) Depth

m

(ft) Bottom

time 30

(100)

27

(90)

24

(80)

21

(70)

18

(60)

15

(50)

12

(40)

9

(30)

Surface

Interval

Chamber

on O2

12m/(40ft)

Total

decomp.

time (min)

Repet.

group.

6 - - - - - - - - - 3 B

15 - - - - - - - 4 7 19 G

20 - - - - - - - 8 21 37 G

25 - - - - - - 6 6 30 50 I

30 - - - - - 3 5 7 37* 65 J

35 - - - - - 5 5 8 46* 77 L

40 - - - - - 6 6 8 54* 87

45 - - - - - 5 6 9 60* 96

50 - - - - 4 5 7 9 72** 115

55 - - - - 5 5 7 13 81** 129

60 - - - - 6 5 8 17 88** 142

65 - - - - 7 5 8 22 99*** 164

48

(130)

70 - - - 3 4 6 8 26

MUST

NOT

EXCEE

D

7 min

108*** 178

6 - - - - - - - - - 3 B

10 - - - - - - - - 6 14 D

15 - - - - - - - 5 11 24 G

20 - - - - - - 5 5 25 43 H

25 - - - - - 3 5 6 30* 57 J

30 - - - - - 5 5 7 42* 72 K

35 - - - - 3 4 6 8 51* 85 M

40 - - - - 4 5 6 8 60* 96

45 - - - - 5 5 7 9 70** 114

50 - - - - 6 6 7 13 80** 130

55 - - - 3 4 6 7 18 89** 145

60 - - - 4 4 6 8 23 101*** 169

65 - - - 5 4 6 9 27 110*** 184

51

(170)

70 - - - 5 5 6 12 30

MUST

NOT

EXCEE

D

7 min

117*** 198






(ft) Depth

m

(ft) Bottom

time 30

(100)

27

(90)

24

(80)

21

(70)

18

(60)

15

(50)

12

(40)

9

(30)

Surface

Interval

Chamber

on O2

12m/(40ft)

Total

decomp.

time (min)

Repet.

group.

5 - - - - - - - - - 3 B

10 - - - - - - - - 7 15 E

15 - - - - - - - 7 15 30 G

20 - - - - - 6 6 28 48 H

25 - - - - - 5 5 7 36* 66 J

30 - - - - 3 4 6 7 47* 80 M

35 - - - - 5 4 6 8 56* 92

40 - - - - 6 5 7 9 66** 111

45 - - - 4 4 5 7 13 78** 129

50 - - - 4 5 5 8 18 88** 146

55 - - - 5 5 6 8 23 101*** 171

54

(180)

60 - - - 6 5 6 9 28

MUST

NOT

EXCEE

D

7 min

110*** 187

5 - - - - - - - - - 3

10 - - - - - - - - 8 16

15 - - - - - - 4 5 19 36

20 - - - - - 4 4 6 30 54

25 - - - - - 7 5 7 41* 73

30 - - - - 5 4 6 8 52* 88

35 - - - 3 4 5 6 9 60* 100

40 - - - 4 4 5 7 11 75** 124

45 - - - 5 5 5 8 17 85** 143

50 - - 3 3 5 6 8 22 99*** 169

57

(190)

55 - - 4 3 5 7 9 27

MUST

NOT

EXCEE

D

7 min

110*** 188






(ft) Depth

m

(ft) Bottom

time 30

(100)

27

(90)

24

(80)

21

(70)

18

(60)

15

(50)

12

(40)

9

(30)

Surface

Interval

Chamber

on O2

12m/(40ft)

Total

decomp.

time (min)

Repet.

group.

5 - - - - - - - - - 4

10 - - - - - - - - 9 17

15 - - - - - - 5 6 22 41

20 - - - - - 5 5 6 31* 60

25 - - - - 5 4 5 7 45* 79

30 - - - 3 4 4 6 9 56* 95

35 - - - 5 4 5 6 10 69** 117

40 - - - 6 4 6 7 15 82** 138

45 - - 4 3 5 6 8 21 92*** 162

60

(200)

50 - - 5 4 4 7 9 27

MUST

NOT

EXCEE

D

7 min

108*** 187

10 - - - - - - - 5 7 20

15 - - - - - - 7 6 25 46

20 - - - - - 7 5 7 36* 68

25 - - - - 6 4 6 8 49* 86

30 - - - 5 4 4 7 8 60* 101

35 - - 3 3 4 6 7 12 76** 129

40 - - 4 4 4 6 8 19 88** 151

45 - - 5 4 5 6 9 25 105*** 182

63

(210)

50 - 3 3 4 6 6 13 29

MUST

NOT

EXCEE

D

7 min

116*** 203






(ft) Depth

m

(ft) Bottom

time 30

(100)

27

(90)

24

(80)

21

(70)

18

(60)

15

(50)

12

(40)

9

(30)

Surface

Interval

Chamber

on O2

12m/(40ft)

Total

decomp.

time (min)

Repet.

group.

10 - - - - - - - 7 7 22

15 - - - - - 4 5 5 28 50

20 - - - - 5 4 5 7 40* 74

25 - - - 4 4 4 6 8 54* 93

30 - - 3 3 4 5 7 9 68** 117

35 - - 5 3 4 6 7 16 83** 142

40 - 3 3 4 4 7 8 23 99*** 174

66

(220) 45 - 4 3 4 5 7 11 28

MUST

NOT

EXCEE

D

7 min

112*** 197

10 - - - - - - - 8 11 27

15 - - - - - 6 4 6 30 54

20 - - - - 6 4 6 7 44* 80

25 - - - 6 3 5 6 9 58* 100

30 - - -5 3 4 5 7 12 75** 129

35 - 3 3 4 4 6 8 19 89** 154

69

(230) 40 - 5 3 4 5 6 9 27

MUST

NOT

EXCEE

D

7 min

107*** 189

10 - - - - - - 4 5 14 31

15 - - - - - 7 5 6 30* 61

20 - - - 4 4 4 5 8 48* 86

25 - - 4 3 4 5 6 9 60** 109

30 - - 6 3 5 5 8 15 80** 140

35 - 5 3 4 4 6 9 23 98*** 175

72

(240) 40 3 3 3 4 6 6 13 28

MUST

NOT

EXCEE

D

7 min

114*** 203




3.4 REPETITIVE DIVING

The Repetitive Diving tables are contained in Tables 3.4.8 (repetitive factors (RF) for surface intervals (SI) for repetitive diving) and 3.4.9 (no-decompression limits for repetitive diving). These Tables have been validated using the Standard Air Decompression and Surface Decompression with Oxygen (Sur D O2) decompression methods to the limit of the “normal air range”.

DOF Subsea prohibits repetitive diving using DCIEM Tables unless approved by the DOF Subsea Manager – Diving Operations.

3.4.1 Repetitive Factors (RF) For Surface Intervals (SI) For Repetitive Diving

In Table 3.4.8 repetitive factors (RF) are given for each repetitive group (RG) letter from A to O, at selected surface intervals (SI) from 15 min up to 18 h. As the SI increases, the RF decreases until it becomes 1.0. A dive is considered a repetitive dive if it is conducted while the RF from the previous dive is greater than 1.0. For example, any dive within 18 h after surfacing from a dive with an RG of H or higher would be considered a repetitive dive.

The RF is used to calculate the effective bottom time (EBT) for the repetitive dive. This EBT, determined by multiplying the actual bottom time of the repetitive dive by the RF, is the total of the actual bottom time and the time that has to be considered to have been already spent at that depth, because of the residual nitrogen remaining in the diver’s body from the previous dive. The EBT is then used to determine the decompression requirements for the repetitive dive.

3.4.2 No-decompression Limits For Repetitive Diving

In Table 3.4.9, the no-decompression (No-D) limits for repetitive dives are shown for different depths as a function of the RF. These No-D limits are actual bottom times and not EBTs; the EBTs of these repetitive No-D limits are less than the No-D limits given in Tables 3.2.2 or 3.3.3 which are for first dives only. With Table 3.4.9, calculations are unnecessary if only No-D repetitive dives are planned. For any repetitive dive, this table should be consulted to determine whether the planned dive can be done as a no-decompression dive or whether decompression will be required.

NOTE: Multiple dives can be performed using the RG of the EBT and the depth of the repetitive dive, however it may be necessary to adjust this RG under certain conditions (see Paragraph 3.4.6).



3.4.2.1 Procedure

The procedure for using the Repetitive Diving Tables 3.4.8 and 3.4.9 is as follows:

1 Find the RG of the first dive (from Table 3.2.2 or 3.3.3 ), and enter Table 3.4.8.

2 Proceed down the RG column to locate the matching RG letter from the first dive, and then proceed horizontally along the same line to the appropriate surface interval (SI) column. Where the RG and the SI intersect, note the RF.

3 Enter Table 3.4.9 at the RF column and proceed down to the applicable depth of the planned repetitive dive. Where the RF and the depth intersect, note the No-D limit for this repetitive dive.

NOTE: The No-D limit obtained is the actual bottom time and not the EBT

3.4.3 Repetitive Dives Not Requiring Decompression

If the actual bottom time of the second dive is less than or equal to the No-D limit in Table 3.4.9, the second dive is a No-D dive (if a third dive is not intended within the next 18 h, no further calculations are necessary).

If a third dive is planned, and the actual bottom time of the second dive is less than the No-D limit, multiply the actual bottom time by the RF to obtain the EBT for the second dive. Find the new RG from the EBT and depth of the second dive from the appropriate decompression table (this RG may need to be adjusted before a third dive can be conducted — see Paragraph 3.4.6).

To find the minimum SI for a No-D dive, enter Table 3.4.9 at the depth of the repetitive dive and proceed horizontally to the intended bottom time of the repetitive dive. Proceed upward in the column to find the RF. Enter Table 3.4.8 at the RG of the first dive and proceed horizontally to the appropriate RF. Proceed upward in the column to determine the minimum SI following the first dive.



3.4.3.1 Example

Example 1:

First dive 18 m (60 ft), bottom time 30 min, surface interval 1 h.

Second dive 15 m (50 ft), actual bottom time 30 min.

Intended third dive 12 m (40 ft) after surface interval 1 h 15min.

Procedure 1:

• RG of first dive = D (from Table 3.2.2). • Enter Table 3.4.8. RF = 1.4. • Enter Table 3.4.9. No-D limit = 45 min. • Actual bottom time of second dive (30 min) is less than No-D limit, therefore

no decompression required at this stage. • For planned third dive, EBT for second dive is 30 × 1.4 = 42 min. • RG for second dive = E (using 15 m (50 ft)/42 min in Table 3.2.3). • From Paragraph 3.4.6, adjust the RG for the second dive. Since SI before

third dive is less than 6 h, and the RG for the second dive (E) is greater than the RG from the first dive (d), no adjustment is necessary therefore RG remains at E.

• Enter Table 3.4.8 for RG = E and SI = 1 h 15min. RF for third dive = 1.5. • Enter Table 3.4.9 . No-D limit for third dive is 100 min.

Example 2:

First dive 24 m (80 ft), bottom time 25 min.

Second dive 15 m (50 ft), bottom time 50 min.

Possible third dive.

Procedure 2:

• RG of first dive = E (from Table 3.2.3). • Enter Table 3.4.9 for second dive. For 15 m (50 ft)/50 min, RF = 1.3. • Enter Table 3.4.8. For a first dive of RG = E, a SI of 2 h is required.

If another dive is planned, EBT for second dive is 50 × 1.3 = 65 min, and the RG = G (from Table 3.2.2).



3.4.4 Repetitive Dives Requiring Decompression

If the actual bottom time of the repetitive dive is greater than the No-D limit in Table 3.4.9, then the repetitive dive requires decompression. Multiply the actual bottom time of the repetitive dive by the RF to obtain the EBT and then use Table 3.2.2, or 3.3.3 to determine the decompression schedule for the depth and EBT of the repetitive dive.

For repetitive bottom times exceeding the No-D limits in Table 3.4.9, but with EBTs less than the No-D limit in Tables 3.2.2 or 3.3.3, a 5 min decompression stop at 3 m (10 ft) is mandatory.

NOTE: The No-D limits in Tables 3.2.2 and 3.3.3 are for first dives only.

Example 1:

First dive 33 m (110 ft), bottom time 15 min, surface interval 40 min.


Procedure 1:

• RG of first dive = D (from Table 3.2.2). • Enter Table 3.4.8. RF = 1.5. • Enter Table 3.4.9. For RF = 1.5, No-D limit for second dive is 7 min. • EBT for second dive is 10 (min) × 1.5 = 15 min. • From Table 3.2.2, decompression schedule is 33 m (110 ft)/15 min.

Example 2:

First dive 18 m (60 ft), bottom time 50 min, surface interval 1 h 45min.


Procedure 2:

• RG of first dive = F (from Table 3.2.2). • Enter Table 3.4.8. RF = 1.5. • Enter Table 3.4.9 For RF = 1.5, No-D limit for second dive is 27 min. • EBT for second dive is 30 (min) × 1.5 = 45 min. • From Table 3.2.2, 18 m (60 ft)/45 min is in the No-D range, therefore

mandatory decompression is 5 min at 3 m (10 ft).



3.4.5 Surface Intervals Less Than 15 Min

Where the SI after the first dive is less than 15 min, if the first and second dives are at the same depth, add the bottom times of the first and second dives together to obtain the EBT for the second dive. If a third dive is planned, use this total time to determine the RG from Table 3.2.2.

If the first and second dives are at different depths, it is necessary to firstly determine the bottom time at the second dive depth which would be equivalent to the first dive. Find the RG from the first dive, proceed to the second dive depth and find the bottom time with the same RG. Add this bottom time to the intended bottom time of the second dive to obtain the EBT for the second dive.

Example 1:



Procedure 1:

• RG of first dive = D (from Table 3.2.2). • EBT of second dive is 30 min + 25 min = 55 min. • From Table 3.2.2 decompression schedule for 18 m (60 ft)/55 min is 5 min at

3 m (10 ft), and RG = G.

Example 2:



Procedure 2:

• RG of first dive = C (from Table 3.2.2). • From Table 3.2.2, a dive with RG = C at 21 m (70ft) has a bottom time of 20

min. • EBT for the second dive is 20 + 20 = 40 min. • From Table 3.2.2, decompression schedule for 21 m (70 ft)/40 min is 5 min at

3 m (10 ft).

NOTE: The repetitive factors (RF) in Table 3.4.9 have been cut off, arbitrarily, at 2.0. It is felt that after a strenuous first dive, the surface interval (SI) should be of sufficient length to reduce the residual nitrogen level of a diver to that degree. Should it be necessary to perform a repetitive dive before the RF reduces to 2.0, the above procedure for surface intervals less than 15 min can be used.



3.4.6 Adjustments For Multiple Repetitive Dives

Repetitive dive tables, by their nature of having fixed limits, cannot take into account every possible diving situation. Repetitive group adjustments may be required in some cases if more than one repetitive dive is planned. These adjustments are necessary to avoid problems on repetitive dives after the first repetitive dive.

For example, if a series of similar No-D repetitive dives are conducted (i.e. similar depth / bottom time / surface interval), it is possible to get locked into a loop resulting in the same RG and RF after each dive. Because decompression will eventually be required, it is necessary to adjust the RG to break out of this loop. Similarly, if a short duration dive follows a longer bottom time dive, the RG calculated for the second dive will be too small and will not take into account the influence of the longer first dive. Thus the second dive RG has to be adjusted upward.

If another dive is planned after a repetitive dive, calculate the RG that corresponds to the depth and EBT of the just completed repetitive dive from the appropriate decompression table (Table 3.2.2, or 3.3.3).

If the surface interval before the next repetitive dive is less than 6 h, and the RG of the just completed repetitive dive is greater than the RG from the previous dive, no adjustment is necessary.

However, if the RG is lower than or equal to the RG of the previous dive, adjust the RG of the just completed dive upward to equal the RG of the previous dive plus one letter.

If the surface interval to the next repetitive dive is more than 6 h, no adjustment is necessary.

Example:



Third dive planned after surface interval 1.5 h.

Procedure: • RG of first dive = D (from Table 3.2.2). • Enter Table 3.4.11. RF = 1.8. • EBT for second (just completed) dive is 8 (min) × 1.8 = 14.4 min. • From Table 3.2.2, RG of second dive is C (21 m (70 ft)/20 min) and is lower

than RG of first (previous) dive. • Adjust RG of second dive from C to E (RG =D +one letter). • Enter Table 3.4.9. RF of second dive = 1.4 (from RG = E and SI 1.30 to 1.59).

NOTE: If the surface interval after the first dive was less than 15 min in the above example, then in accordance with Paragraph 3.4.5, the EBT of the second dive would be 25 + 8 = 33 min. Consequently, the RG would be E for the second dive.



3.4.7 Flying after diving

After a no-decompression dive, allow enough surface interval time to elapse for the RF to diminish to 1.0 before flying. After a decompression dive, a minimum of 24 h surface interval is required before flying.



3.4.8 Table - Repetitive Factors (RF) For Surface Intervals (SI) For Repetitive Diving

Repetitive factors (RF) for surface intervals in hr.min

Repetitive

group

(RG)

0.15

to

0.29

0.30

to

0.59

1.00

to

1.29

1.30

to

1.59

2.00

to

2.59

3.00

to

3.59

4.00

to

5.59

6.00

to

8.59

9.00

to

11.59

12.00

to

14.59

15.00

to

18.00

A 1.4 1.2 1.1 1.1 1.1 1.1 1.1 1.1 1.0 1.0 1.0

B 1.5 1.3 1.2 1.2 1.2 1.1 1.1 1.1 1.1 1.0 1.0

C 1.6 1.4 1.3 1.2 1.2 1.2 1.1 1.1 1.1 1.0 1.0

D 1.8 1.5 1.4 1.3 1.3 1.2 1.2 1.1 1.1 1.0 1.0

E 1.9 1.6 1.5 1.4 1.3 1.3 1.2 1.2 1.1 1.1 1.0

F 2.0 1.7 1.6 1.5 1.4 1.3 1.3 1.2 1.1 1.1 1.0

G — 1.9 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.1 1.0

H — — 1.9 1.7 1.6 1.5 1.4 1.3 1.1 1.1 1.1

I — — 2.0 1.8 1.7 1.5 1.4 1.3 1.1 1.1 1.1

J — — — 1.9 1.8 1.6 1.5 1.3 1.2 1.1 1.1

K — — — 2.0 1.9 1.7 1.5 1.3 1.2 1.1 1.1

L — — — — 2.0 1.7 1.6 1.4 1.2 1.1 1.1

M — — — — — 1.8 1.6 1.4 1.2 1.1 1.1

N — — — — — 1.9 1.7 1.4 1.2 1.1 1.1

O — — — — — 2.0 1.7 1.4 1.2 1.1 1.1



3.4.9 Table - No-Decompression Limits For Repetitive Diving

Depth No-D limits (min) for repetitive factors (RF)

m (ft) 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0

9 (30) 272 250 230 214 200 187 176 166 157 150

12 (40) 136 125 115 107 100 93 88 83 78 75

15 (50) 60 55 50 45 41 38 36 34 32 31

18 (60) 40 35 31 29 27 26 24 23 22 21

21 (70) 30 25 21 19 18 17 16 15 14 13

24 (80) 20 18 16 15 14 13 12 12 11 11

27 (90) 16 14 12 11 11 10 9 9 8 8

30 (100) 13 11 10 9 9 8 8 7 7 7

33 (110) 10 9 8 8 7 7 6 6 6 6

36 (120) 8 7 7 6 6 6 5 5 5 5

39 (130) 7 6 6 5 5 5 4 4 4 4

42 (140) 6 5 5 5 4 4 4 3 3 3

45 (150) 5 5 4 4 4 3 3 3 3 3



3.5 OMITTED DECOMPRESSION

The Omitted Decompression table is contained in Table 2.6.4. Where a diver has omitted decompression but remains asymptomatic, the procedure is dependent on the availability of a compression chamber.

NOTE: The flow chart at 3.5.5 shows an omitted decompression flow chart to assist in determining the appropriate course of action when using the decompression tables and procedures in this Standard.



3.5.1 Compression Chamber Immediately Available (Less Than 7 Min)

Where a compression chamber is available to a diver within 7 min of the diver leaving the water, the procedure is as follows:

1 If the 9 m (30 ft) or deeper stops were not completed, either -

• treat in accordance with Table 2.6.4 if the total omitted decompression time is less than 30 min; or

• treat in accordance with Table 2.6.5 if the total omitted decompression time is equal to or greater than 30 min.

2 If the 9 m (30 ft) stop was completed with no previous decompression omitted, recompress the diver in the chamber on O2 to 12 m (40 ft) and decompress in accordance with Table 3.3.3

3 When using Table 3.3.3 for any dive profile not including a 9 m (30 ft) in-water stop, if the surface interval - Sur D O2 exceeds 7 min, treat in accordance with Table 2.6.4

NOTE: If the surface interval — Sur D O2 is completed within the 7 min, the diver cannot incur omitted decompression

Example:

Dive 39 m (130 ft), bottom time 40 min.

Table 3.2.2 calls for; • 12 m—4 min stop • 9 m—7 min stop • 6 m—9 min stop • 3 m—39 min stop

Situation:

Diver surfaces after completing the 12 m (40 ft) stop, the 9 m (30 ft) stop and 3 min of the 6 m (20 ft) stop. Diver is asymptomatic and a compression chamber is available.

Procedure: • Since the diver has completed the 9 m (30 ft) stop, dive on O2 in compression

chamber to 12 m (40 ft). • Enter Table 3.3.3. For 39 m (130 ft)/40 min dive, 36 min on O2 is called for. • Add 5 min air break after 30 min on O2 for a total decompression time of 41

min in the compression chamber.



3.5.2 Compression Chamber Not Immediately Available

Where a compression chamber is not immediately available to a diver having omitted decompression, the preferred action is to get the diver to a compression chamber for treatment. The diver should receive 100% O2 by double-seal oral nasal mask en route to the compression chamber. However, the supervisor has the following options if the situation warrants it:

• Return the diver to the next deeper stop where the omission occurred. Continue decompression with the original schedule (see Example 1).

• If no deeper stop was called for, spend the time of the first stop at the next deeper stop and complete the total schedule (see Example 2).

Example 1:


Table 3.2.3 calls for— • 12 m—4 min stop • 9 m—7 min stop • 6 m—9 min stop • 3 m—39 min stop

Situation 1:

Diver surfaces after completing the 12 m (40 ft) stop, the 9 m (30 ft) stop and 3 min of the 6 m (20 ft) stop. Diver is asymptomatic and a compression chamber is not available.

Procedure 1: • Recompress immediately to either 9 m for 7 min (Table 3.2.2). • Resume schedule beginning with the 6 m (20 ft) stop.

Example 2:


Table 3.2.3 calls for— • 12 m—4 min stop • 9 m—7 min stop • 6 m—9 min stop • 3 m—39 min stop

Situation 2:

On ascent to 12 m (40 ft) stop, diver loses control and surfaces (blow-up). Diver is asymptomatic and a compression chamber is not available.

Procedure 2: • Return diver to 15 m for 4 min (Table 3.2.2) or 50 ft. • Complete total decompression schedule



3.5.3 Violation of 7 minute surface interval — Sur D O2

Where the 7 minute surface interval—Sur D O2 has been exceeded but the diver remains asymptomatic, either—

• treat in accordance with Table 2.6.4 if the surface interval—Sur D O2 exceeds 7 min but is less than 30 min; or

• treat in accordance with Table 2.6.5, if the surface interval—Sur D O2 equals or exceeds 30 min.

3.5.4 Decompression Stress During Surface Interval—Sur D O2

During the surface interval (SI) of a Sur D O2 dive, the required decompression has been intentionally violated in order to take the diver out of the water and complete the decompression in a recompression chamber. At the completion of the SI, the diver is re-pressurized in the chamber to a depth of 12 m (40 ft), deeper than called for by the decompression schedule. The diver is given additional decompression during the chamber phase of the Sur D O2 profile for the increased stress of the SI.

During the SI, the diver is exposed to a higher level of decompression stress than would be encountered if in-water decompression only had been executed. Therefore, the diver may experience signs or symptoms of decompression stress. Manned validation has indicated that when symptoms do occur during the SI, they are almost always very mild and late into the SI.

In addition, the symptoms usually completely resolve during the compression to 12 m (40 ft) in the chamber. Experimental dives have demonstrated that the divers who experienced SI symptoms had the same incidence of decompression illness after the completion of the dive as those divers who did not experience signs or symptoms during the SI.

Therefore, during Sur D O2 diving, when all signs and symptoms of SI stress have completely resolved by the time the diver is confirmed on oxygen at 12 m (40 ft), the decompression profile is to be completed as planned.

When the signs and symptoms of SI stress have not completely resolved by the time the diver is confirmed on oxygen at 12 m (40 ft), it should be treated as decompression illness. The diver should be immediately compressed to 18 m (60 ft), treatment in accordance with table 2.6.5 (see also section 4.8, and section 4 Annexe C) initiated, and a medical practitioner appropriately trained in underwater medicine contacted.



3.5.5 DCIEM - Omitted Decompression Flow Chart



3.6 Depth Corrections For Diving At Altitude

Depth corrections for diving at altitude are given in Tables 3.6.2. The depth corrections in these tables have not been experimentally validated and have been derived by recalculating the Standard Air Decompression tables (the Table at 3.2.2) at different altitudes. They should not be used with any other published tables.

The corrections for altitude shown in Tables 3.6.2 only apply for divers who have been acclimatized at that altitude, i.e. for those who have spent at least 12 to 24 h at the altitude of the dive site. Corrections to the depth would be greater for those who have not acclimatized.

If diving at altitude is conducted within 24 h of arriving at the altitude of the dive site, apply an additional 3 m (10 ft) to the actual maximum depth of the dive used in Tables 3.6.2 After 24 h, this additional correction is not required (see Example 2).

3.6.1 Procedure

The procedure for using Tables 3.6.2 is as follows:

1 Establish the altitude of the dive site and determine the actual maximum water depth of the dive.

2 Find the correction for the actual depth according to the altitude from Table 3.6.2 and add this correction to the actual depth to obtain the effective depth (ED).

3 Determine the decompression schedule from the appropriate decompression table by applying the effective depth and the actual planned bottom time.

4 Replace the stop depths from the normal decompression table with the actual stop depths shown at the bottom of Table 3.6.2 (the stop times are not changed).

5 Decompress on this altitude schedule in accordance with normal procedures using the regular travel rates, unless the altitude is above 1524 m (5000 ft), in which case reduce the ascent rate to 15 m (50 ft)/min.



Example 1:

Altitude of dive site 2195 m (7200 ft).

Dive 30 m (100 ft), Bottom time 23 min.

Decompression by Standard Air Decompression (Table 3.2.2).

Procedure 1: • Enter Table 3.6.2Depth correction for 2195 m (7200 ft) is +9 m (+30 ft). • Effective depth (ED) of dive is 30 +9 =39 m(100 + 30 = 130 ft). • For 39 m/25 min Table 3.2.2 calls for

o 6 m—7 min stop o 3 m—11 min stop o Repetitive group H

• From Table 3.6.2, actual decompression schedule, corrected for stop depths, as follows:

o 7.5 m—5 min stop o 5.0 m—7 min stop o 2.5 m—11 min stop

Example 2:

Altitude of dive site 2195 m (7200 ft).

Dive 30 m (100 ft), bottom time 23 m.

Unacclimatised diver.

Decompression by Standard Air Decompression (Table 3.2.2).

Procedure 2:

Apply depth correction. Actual maximum depth of dive is 30 +3 =33 m (100 + 10 = 110 ft).

Enter Table 3.6.2. Depth correction for 2195 m (7200 ft) is +12 m (+40 ft).

Effective depth (ED) of dive is 33 + 12 = 45 m (110 + 40 = 150 ft).

For 45 m/25 min, Table 3.2.2 calls for— • 12 m—4 min stop • 9 m—5 min stop • 6 m—8 min stop • 3 m—23 min stop • Repetitive group J

From Table 3.6.2, actual decompression schedule, corrected for stop depths, as follows:

Table 3.6.2 calls for — • 9.5 m—4 min stop • 7.0 m—5 min stop • 5.0 m—8 min stop • 2.5 m—23 min stop



3.6.2 Table - Depth Corrections—Diving At Altitude (Metres)

Depth correction at altitude, m Actual depth

m

100 to

299

300 to

599

600 to

899

900 to

1199

1200to

1499

1500to

1799

1800 to

2099

2100to

2399

2400to

3000 9 +0 +3 +3 +3 +3 +3 +3 +6 +6

12 +0 +3 +3 +3 +3 +3 +6 +6 +6

15 +0 +3 +3 +3 +3 +6 +6 +6 +6

18 +0 +3 +3 +3 +6 +6 +6 +6 +9

21 +0 +3 +3 +3 +6 +6 +6 +9 +9

24 +0 +3 +3 +6 +6 +6 +9 +9 +12

27 +0 +3 +3 +6 +6 +6 +9 +9 +12

30 +0 +3 +3 +6 +6 +9 +9 +9 +12

33 +0 +3 +6 +6 +6 +9 +9 +12 +15

36 +0 +3 +6 +6 +6 +9 +9 +12 +15

39 +0 +3 +6 +6 +9 +9 +12 +12 +15

42 +0 +3 +6 +6 +9 +9 +12 +12 +18

45 +3 +3 +6 +6 +9 +9 +12 +15 +18

48 +3 +6 +6 +9 +9 +12 +12 +15 +18

51 +3 +6 +6 +9 +9 +12 +15 +15 +21

54 +3 +6 +6 +9 +9 +12 +15 +15

57 +3 +6 +6 +9 +12 +12 +15

60 +3 +6 +6 +9 +12 +12

63 +3 +6 +6 +9

66 +3 +6

69 +3

Actual decompression stop depth at altitude, m Sea Level Stop

depth, m

100 to

299

300 to

599

600 to

899

900 to

1199

1200to

1499

1500to

1799

1800 to

2099

2100to

2399

2400to

3000

3 3.0 3.0 3.0 3.0 3.0 2.5 2.5 2.5 2.5

6 6.0 6.0 6.0 5.5 5.5 5.0 5.0 5.0 4.5

9 9.0 9.0 8.5 8.5 8.0 7.5 7.5 7.0 7.0

12 12.0 12.0 11.5 11.0 10.5 10.0 10.0 9.5 9.0

15 15.0 14.5 14.0 13.5 13.0 12.5 12.0 12.0 11.5

18 18.0 17.5 17.0 16.5 16.0 15.0 14.5 14.0 13.5

21 21.0 20.5 20.0 19.0 18.5 17.5 17.0 16.5 16.0

24 24.0 23.5 22.5 21.5 21.0 20.0 19.5 19.0 18.0

27 27.0 26.0 25.5 24.5 23.5 22.5 22.0 21.0 20.0



4.0 EMERGENCIES - DIVING

An emergency, by definition, is an unforeseen combination of circumstances the resulting state of which calls for immediate action. Because of the characteristics of the underwater environment, a situation which might only be annoying on the surface may assume life or death proportions for a working diver.

By training and experience, a diver must be able to handle the wide range of actual and potential emergency situations which he may encounter. He must be able to separate the important from the trivial, while at the same time recognising the dangers which a seemingly minor symptom or event may foreshadow. He must be able to identify and properly react to the warning signs of various physiological disorders, whether affecting himself or other divers. He must have a working knowledge of the most effective methods for handling physical emergencies (such as entrapment or malfunctioning equipment) as well as a basic knowledge of the correct steps to be taken in treating medical emergencies.

And, most importantly, he must be able to work toward solving the emergency while he himself is under the emotional and physical stress which is almost certain to be one component of any emergency situation.

Knowledge and training are vital. Men and women who are well trained, well rested, alert and confident only rarely cannot cope with an emergency. An operation that is thoroughly planned, with a carefully paced workload and the prior organisation of all necessary personnel, equipment and supplies, tends to be a safer operation. Equipment in good repair, properly maintained and not jury-rigged or “adapted” to a non-designed task, is usually safe equipment. While the environment of the dive cannot be directly controlled, it can be understood, and any hazardous elements provided for with special training, equipment or scheduling.



4.1 PERSONNEL CASUALTY PROCEDURES

Since all divers must have a good knowledge of the principals of first aid, this section will be useful as a guide and reference. See DOF Subsea DOM section 9.5.

Remember, first aid is just that. The administering of emergency first aid must not take the place of proper medical or surgical treatment.

The purposes of first aid are:

• To save lives.

• To prevent further injury.

• To preserve vitality and resistance to infection.

In the administering of first aid, there are four primary tasks. In order of priority they are:

• Assure clear airway.

• Restore breathing.

• Assure heart function.

• Stop massive bleeding.



4.2 RESUSCITATION

Resuscitation is a general term, which covers all the measures taken to restore vital signs, particularly the breathing and heartbeat. These measures include pulmonary resuscitation to restore breathing and cardiac resuscitation to establish normal heart function.

4.2.1 Expired Air Resuscitation (EAR)

Of the several types of manual pulmonary resuscitation which have been developed (i.e.: back pressure – arm lift, back pressure – hip lift, chest pressure – arm lift), the EAR method is the most effective and is definitely the choice for initial resuscitation. The others may be useful if the victim is vomiting or facial injury makes the EAR method impractical.

The use of an airway not only offers the aesthetic advantage, but also helps to maintain a clear air passage. Resuscitation must be continued without interruption. The treatment of other injuries can be administered during resuscitation.

A bag or mechanically-powered resuscitator can be substituted for EAR when it becomes available. Oxygen may also be administered to assist respiration. Do not delay starting resuscitation to find an Ambu bag or Emmerson device.

NOTE: Remember the O2 in the bloodstream is elevated above the normal level when diving. You may have as much as twenty minutes before brain damage occurs. Do not hesitate to give resuscitation to a diver who has stopped breathing for more than four minutes.

4.2.2 Cardiac Resuscitation

Cardiac arrest may result from electrical shock or asphyxia, or it may be caused by a combination of factors such as hypoxia, shock or embolism. There are may other causes, but the immediate problem is not the cause but to initiate cardiac massage. Closed-chest cardiac massage is a method for artificially continuing the flow of blood to the central nervous system and other vital organs.

If the heart has been interrupted for more than four minutes, irreversible brain damage will generally result. If, however, the heart has been interrupted for a period of more than 4 minutes due to drowning in extremely cold water, brain damage has been known to be retarded by some considerable time. However, cardiac massage should be continued until the victim is pronounced dead by a doctor or medic, or until you are unable to continue.



4.3 BLEEDING AND SHOCK

4.3.1 Controlling Massive Bleeding

The best way to stop serious bleeding is by the application of pressure. In nearly all cases, bleeding can be stopped if pressure is applied directly to the wound.

If direct pressure does not stop the bleeding, pressure should be applied to the appropriate pressure point.

In those very rare cases where bleeding is so severe that is cannot be controlled by either of these methods, pressure can be applied by means of a broad restrictive bandage. A tourniquet is used as a last resort to preserve life, as the risk to the limb is great.

4.3.2 Shock

Treat for shock in all cases of injury or sudden illness. Have the person lie on his/her back with head lower than the feet. Cover with blankets or coats, etc. to maintain body temperature. Do not overheat. Administer 100% oxygen if available.



4.4 TEMPERATURE RELATED INJURY

4.4.1 Hypothermia

Cold injury should never be treated lightly because of the possibility of tissue loss and nerve damage.

There are three stages to hypothermia. They are referred to as cold, mild hypothermia and severe hypothermia.

4.4.1.1 Cold — (Skin temperature affected)

When a diver is cold the body’s core temperature does not drop significantly, whereas skin temperature is obviously below normal. Signs and symptoms of cold are goose bumps, shivering, pale to blue skin colour, and there may be an increased rate of breathing to fulfil oxygen requirements to produce energy and maintain body heat. As blood is withdrawn from the extremities in an effort to maintain core temperature, numbness of toes and fingers occur. Signs and symptoms of cold are the early warning signs that our core temperature can no longer be maintained and will begin to fall, i.e. hypothermia will occur.

4.4.1.2 Mild Hypothermia — (Body core temperature dangerously affected)

As further heat is lost to the environment, the body shuts down larger blood vessels, particularly those in the limbs. As a result of this lack of blood supply, in-coordination and cramping occur and the diver will have difficulty performing fine tasks. Shivering becomes spasmodic and uncontrollable. As the brain cools down the patient becomes confused and loses interest.

4.4.1.3 Severe Hypothermia — (Critical, death is imminent)

As core temperature gets progressively lower, the patient will go into a state of collapse, shivering will stop and muscle rigidity occurs. The patient may also have slurred speech or even lose the ability to speak. The patient can go into a state of semi to total unconsciousness. Breathing difficulties and heart irregularities will also occur as the heart itself cools.

4.4.1.4 Treatment

When the body core temperature has begun to fall the vast majority of stored food and energy reserves have been consumed. Unless specifically treated, the patient will die without corrective measures being introduced quickly.

• Cold — Dry clothes, warm drink, rest and sweet fluids.

• Mild Hypothermia — Gentle re-warming using body heat of others, electric blanket, glucose and warm drinks.

• Severe Hypothermia — Treat very gently, remove from water with care, needs hospitalisation.



4.4.2 Heat Stroke

This is sometimes called “sun stroke” and is a very serious condition which results in the failure of the heat regulating mechanism of the body.

4.4.2.1 Signs and Symptoms

Heat stroke is caused when persons exposed to excessive heat perspire and the loss of water leads to a decrease in plasma volume. This condition will lead to a decreased cardiac output resulting in a decreased blood flow to the skin. As the blood supply to the skin becomes inadequate, a major pathway for heat loss is decreased.

Body temperature will rise causing heat stroke. This condition can lead to cardiac failure and death. The most striking characteristic of heat stroke is lack of sweat. The skin is dry and flushed. Early signs include headache, blurred vision and vomiting.

4.4.2.2 Treatment

Move the victim to a cool place. Remove as much clothing as possible; place the victim on his / her back with head and shoulders slightly raised. When the victim regains consciousness, administer small amounts of cool (but not cold) water. Absolutely no stimulants or hot drinks.

NOTE: If no response, a more drastic cooling method must be employed to initially cool the victim. Ice water may be applied externally. Once the temperature starts to drop, remove to a cool place.

4.4.3 Treatment for Heat Exhaustion (Hyperthermia)

This is the bodily reaction to excessive heat. In doing so, the body sweats profusely and loses large amounts of salt and water.

4.4.3.1 Signs and Symptoms

Victims may complain of headache, dizziness, nausea and weakness; temperature is subnormal and pulse is likely to be weak and rapid.

4.4.3.2 Treatment

Move the victim to a cool, well-circulated are, but do not allow him / her to chill; loosen all tight clothing; lie the victim on his / her back with feet and legs slightly elevated; sponge with cold water and give fluids to drink (i.e. water).



4.5 MARINE ANIMAL INJURIES

Most marine animals have evolved a means of protection from potential predators, or the means to be efficient predators. Spines, teeth, speed, cryptic colourations, and a huge range of irritants and toxins which can act either externally or internally, are examples of adaptations to these ways of life.

Naturally one or more of these attributes can be equally effective against people. The type of injury resulting from an unfavourable encounter can be divided into five categories.

• Bites.

• Puncture wounds.

• Stings.

• Internal poisoning.

• Electric shocks.

4.5.1 Bites

4.5.1.1 Non-venomous Bites

Some marine animals, such as groper, killer whales, seals and sharks have been known on rare occasions to injure divers.

The wounds from bites are generally extensive with ragged edges. Tissue injury and haemorrhaging are usually severe. Blood loss, shock and secondary infection are the main features causing concern. In severe cases, quick and efficient first aid is of vital importance.

It is important to note, however, that the most likely cause of this type of injury will be boat propellers, broken glass or divers falling and hurting themselves.

Management

1 DRABC.

2 Observe and assess the signs and symptoms.

3 Broad pressure bandage (pressure immobilisation).

4 Splint.

5 A second broad pressure bandage.



4.5.1.2 Venomous Bites

There are principally two animals that are known to bite causing injection of venom into the wound. They are blue-ringed octopus and the sea snake.

Blue-ringed Octopus:

A blue ringed octopus grows to a maximum of 20 cm from tip to tip of its tentacles. When undisturbed, this animal has a yellowish-brown colour with dull ringed markings on the tentacles and stripes on the body. When disturbed, these dull markings become iridescent blue. The initial bite is almost painless. After about 15 minutes the bite becomes swollen, resembling a mosquito bite. A few minutes after the bite a rapid, painless paralysis results. The symptoms progress as follows:

1 Numbness around the mouth and neck, which may cause difficulties in swallowing.

2 Nausea and vomiting.

3 Breathing difficulties arise fairly quickly.

4 The eye muscles gradually become paralysed.

5 General weakness and difficulty with coordination leads to complete paralysis which persists for 4 to 12 hours.

Sea Snakes:

There are a number of different species of this marine reptile, some being more dangerous than others. The toxins interfere with nerve and muscle function. The initial puncture is noticed but is not painful. Symptoms may take 10 minutes to several hours to manifest themselves. Restlessness, nausea and vomiting may occur, followed by a general stiffening and aching. Weakness develops into paralysis and spreads. This may be preceded by muscular twitching and spasms. Respiratory and cardiac distress and failure may also occur.

Management

1 DRABC.



4 Splint.




Cone Shells:

Although more prevalent in tropical waters, cone shells are found in temperate waters. While not strictly a “bite” these animals have a minute, rasp-like feeding appendage (radula) which can thrust out of the narrow end of the shell. The radula has a series of 1-20 teeth which penetrate the skin and inject the venom. These specialised teeth are generally used for immobilising prey, but may also be used for protection. The shell should never be picked up by divers.

The toxins injected affect the nerve muscle function. The initial puncture may be painless or associated with excruciating pain. Numbness and tingling may extend from the bite to involve the whole body, particularly the mouth and lips. This process takes around 10 minutes. Mild to severe muscular paralysis may result within 10-30 minutes, including respiratory paralysis. Cardiac arrest may also occur. The patient's general condition deteriorates for 1-6 hours, after which improvement is likely.

Management

1 DRABC.



4 Splint.




4.5.2 Puncture Wounds

These generally result from spines or darts. They may be complicated by toxins or irritants.

4.5.2.1 Puncture Wounds Without Venom

This type of wound is probably the most common injury resulting from contact with the marine animal. These wounds often occur while cleaning fish, and while handling specimens.

Sea urchins are the most common marine animal encountered by divers that cause a puncture wound.

The spines of these animals are long, sharp and brittle. The spines tend to break off within the tissues. Pain occurs immediately after penetration. Swelling or inflammation usually occurs. The area of inflammation may increase and begin to ache. This ache can extend to involve the whole limb. The lymph glands become tender and swollen. General weakness and shock may result.

With sea urchin spines, removal should not be attempted unless it can be accomplished without breaking the spine.

4.5.2.2 Puncture Wounds With Venom

Many animals are particularly well endowed with spines. Fish such as the butterfly cod (lionfish), stonefish, and catfish are common examples found within tropical waters. Stingrays also have spines. In these fish, the spines are covered by a sheath which is pierced and displaced when contact is made with the victim. Venom then passes along the spine into the wound. Severe pain is experienced at the affected site. This gradually increases in intensity. The intense pain lasts for several hours and may persist as a dull ache for a few days. The wound is susceptible to secondary infection. Pain may extend to the lymph glands of the groin and armpit. Distress as a result of the pain may lead to mild delirium. Nausea, vomiting, sweating, fever and shock may also result. Respiratory failure may occur. Weakness and exhaustion may last for several days.

It is unlikely to be fatal except in the case of the stonefish. These fish have short stout spines covering the head and gill covers which may inflict a simple puncture wound.

Management

1 DRABC



4 Splint

5 A second broad pressure bandage

4.5.3 Stings



Animals that have tentacles coated with stinging cells (nematocysts) belong to a group of creatures called the cnidaria (hollow gutted animals) or coelenterates and include corals, anemones, hydroids, fire urchins and sea jellies.

Examples of the better known species are blue-bottle, mauve stinger, jimble, and the most dangerous of all, the box jelly. Portuguese Man-of-War is a compound hydroid rather than a sea jelly but gives similar symptoms.

Generally, a few seconds after contact, a stinging sensation is felt and this increases in intensity for a few minutes. A red coloured reaction surrounds the area of contact and may rise up in the form of a pimple. Lesions, weals and blisters often result, the shape of which may be characteristic of the animal responsible. The pain may extend to the lymph glands of the groin and armpit.

General symptoms include abdominal pains, cramps, muscular aches, respiratory distress, sweating, anxiety and restlessness. Nausea and vomiting may also occur. Symptoms generally diminish within 4-12 hours. Convalescence may take up to a week. In the case of the box jelly, if death occurs, it usually occurs within the first 10 minutes.

4.5.3.1 Management

Box Jelly Fish - Priority lies with immediate and appropriate resuscitation. Vinegar inhibits the discharge of all known box jelly fish nematocysts. So it should be used to douse all known box jelly fish stings. The stings can then be scraped off with a knife. Apply vinegar first and then a pressure immobilisation bandage. Soak the bandage in vinegar if practicable. Administer anti-venom if available. Vinegar plays no role in pain relief therefore pain relief methods must be used together with treatment for shock.

Other Jelly Fish Stings - Vinegar may actually discharge other jelly fish stings. Therefore, for these painful but not life threatening stings, nematocyst inhibition is not as high a priority. The stings can be scraped off with a knife or picked off using the thicker pads of the fingers. Ice packs or cold packs can then be applied for pain relief, much like treating a burn. Ice should not be applied directly as the ice melting may cause the nematocysts to discharge.



4.5.4 Electric Shocks

Electric rays or numbfish are slow and ineffective swimmers. The electric discharge varies from 8 to 220 volts. The ray can deliver a successive series of shocks. The electric shock may be disabling, a major threat coming from drowning. Recovery is uneventful and treatment is not usually required.

4.5.5 Marine Animal Injuries in Remote Areas

In the situation where medical aid is unavailable for some hours, extra care must be taken to avoid the potential injuries from marine organisms. Dive supervisors have the responsibility to ensure the presence of a comprehensive first aid kit which should be put together in consultation with a doctor who is aware of the added problems associated with diving and the marine world. These should be addressed in the DPP.



4.6 GAS POISONINGS AND OTHER RELATED PROBLEMS

Any emergency in a diving situation could result in a requirement for medical treatment. Many of these emergencies are analogous to those encountered in any environment, and informal first aid measures are employed. In some circumstances, such as traumatic injuries occurring under water, the need for decompression may complicate procedures.

Thus the need for adequate dive decompression may affect wound management techniques. In serious situations a judgement may be required to bypass normal decompression and risk decompression sickness in favour of rendering immediate aid to the diver.

Aside from the complications introduced by recompression considerations. This section concerns disorders which are unique to diving, require special procedures, and are not treated by recompression. For convenience these problems can be divided into two areas.

• Respiratory Emergencies, as directly related to the quantity and quality of the breathing supply.

• In-water Emergencies with direct medical involvement.

The most serious conditions which can apply to any of these categories have already been covered:

• Cessation of breathing

• Cardiac arrest

• Massive haemorrhage

A potentially serious symptom which may be common to these categories is loss of consciousness which may be both a warning of a severe problem and a complicating factor in any diagnosis.

Loss of consciousness can be the result of near-drowning, inadequate oxygen, an oxygen convulsion or an excess of carbon dioxide in the blood. But in diving, loss of consciousness must be considered to be a symptom of the most dangerous problems – gas embolism and decompression sickness. Recompression should be given in almost every case of unconsciousness simply because it is seldom possible to be certain that it is not essential. If satisfied that recompression is not called for in a given case, then treatment can progress along other lines, as outlined in the following sections.



4.6.1 Respiratory Emergencies

All human life is directly dependent upon the quantity and quality of its breathing mixture. Any deviations from established standards can result in a number of respiratory problems. Because of the particular nature of the underwater environment, any such problem – which on the surface might easily be handled as transient annoyance – must be handled as an emergency.

Not all respiratory problems must necessarily result in the termination of the dive – if they are identified and corrected soon enough. With most, however, the need to ensure the safety of the diver will outweigh an operational requirement to complete a planned dive, and the diver should be brought to the surface for treatment and thorough examination by medical personnel. Beware of the diver who reports from the bottom “ I think I’m OK now” and wants to continue his assignment.

Every diver and every other member of the diving team must know the warning signs and symptoms of each of these problems:

• Oxygen Deficiency (hypoxia)

• Carbon Dioxide Poisoning

• Carbon Monoxide Poisoning

• Asphyxia

• Strangulation

• Chemical Irritants

• Nitrogen narcosis

• Oxygen Poisoning (toxicity)



4.6.2 Oxygen Deficiency

Although the specific cause varies, the following disorders all result in the same condition – a shortage of oxygen reaching the cells for normal metabolism. In summary, these disorders are:

• Hypoxia, caused by loss or inadequacy of the air supply.

• Carbon Dioxide Poisoning, resulting from inadequate ventilation of apparatus, over-exertion, controlled or “skip” breathing, excessive dead space in equipment.

• Carbon Monoxide Poisoning, caused by induction of exhaust fumes into the air supply compressor.

• Asphyxia, simultaneous oxygen deficiency and carbon dioxide excess usually caused by loss or inadequacy of the air supply.

• Strangulation, obstruction of the airway by a foreign object, laryngeal spasm or abnormal swelling.

• Chemical irritants, presence of irritating chemicals contaminating the air supply resulting in pulmonary oedema.

4.6.2.1 Symptoms

The following signs and symptoms may be noted in situations involving oxygen deficiency.

• Laboured breathing • Headache

• Lack of muscular control • Nausea

• Mental confusion • Chest Discomfort

• In-coordination • Unconsciousness

• Bad taste • Weakness

4.6.2.2 Treatment

The following procedure should be followed if oxygen deficiency is suspected:

1 Abort the dive.

2 Switch to an alternate air supply. Send down the standby diver to assist (Standby diver to be on a separate air supply if possible).

3 Thoroughly ventilate the apparatus.

4 Administer 100% oxygen when diver is on the surface.

4.6.3 Nitrogen Narcosis



The narcotic effect of high partial pressures of nitrogen can produce euphoria, disorientation, lapses of rationality or judgement, and other behaviour similar to that of alcoholic intoxication. Nitrogen narcosis is normally encountered below 100 feet and may result from exceeding established depth limits.

4.6.3.1 Treatment

• Reduction of the nitrogen partial pressure is the standard procedure for treatment. Specifically:

• Diver should ascend to a shallower depth.

• If mental acuity is not restored, abort the dive.



4.6.4 Oxygen Toxicity

Oxygen toxicity affects the lungs (pulmonary toxicity) or the central nervous system (CNS oxygen toxicity).

4.6.4.1 Pulmonary Toxicity

Pulmonary toxicity may occur during long oxygen exposures such as prolonged recompression treatment tables.

• Symptoms; Substernal burning and severe pain on inspiration.

• Treatment; The onset of central chest pain or other indications of this complication may require cessation of oxygen therapy pending medical assessment. Reference section G3.1 AS/NZS2299.1 :2007.

Air breaks between cycles may be tailored by a medical doctor to suit individual patient’s response to treatment.

4.6.4.2 CNS Oxygen Toxicity

CNS oxygen toxicity is the most common and most serious form of oxygen toxicity. CNS oxygen toxicity is usually not encountered unless the partial pressure of oxygen exceeds 1.4 ATA. Signs and symptoms of CNS oxygen toxicity include the following:

• Vision; any abnormality, such as tunnel vision (a contraction of the normal field of vision, i.e. tunnel vision).

• Ears; abnormal sounds, especially ringing or roaring.

• Nausea; may be intermittent.

• Twitching; usually first appears in the lips or other facial muscles. This is the most frequent and clearest symptom.

• Irritability; Any change in behaviour, including anxiety or confusion.

• Dizziness.

• Tingling; of the extremities.

These symptoms may occur singly or together. They occur in no particular order and there is no one symptom which could be considered more serious than another, or which is a better warning of an impending convulsion. The first sign of CNS oxygen toxicity may be a convulsion which occurs with little or no warning.

Treatment: Procedures for treating CNS oxygen toxicity involve immediate reduction in oxygen partial pressure and protection of the diver from physical injury if he begins to convulse.



Specifically:

• Stop mask breathing and breathe chamber atmosphere.

• If symptoms persist, switch to an air decompression schedule.

• If the diver is having convulsions, protect him from physical harm and protect his tongue with a padded depressor or similar.



4.6.5 Drowning

A swimmer can fall victim to drowning because of over-exertion, panic, inability to cope with rough water, exhaustion, or the effects of cold water or heat loss. These same factors can affect a diver, but if he is properly equipped, trained and monitored by a buddy or a surface tender, drowning should be a remote possibility. Unfortunately, divers do drown – even when equipped, trained and tended.

Divers wearing lightweight or scuba gear can drown if they lose or ditch their mask or mouthpiece. This could be the direct result of the failure of the air supply, or of panic in a hazardous situation. The scuba diver, because he is so directly exposed to the environment, can be directly affected by the same conditions which may cause a swimmer to drown.

The prevention of drowning is best insured by the establishment of, and thorough training in, safe diving practices coupled with the careful selection of diving personnel. A physically fit, confident diver, equipped with proper gear, should not easily fall victim to drowning. At the same time, however, over confidence, in both self and equipment can give a feeling of security that might lead a diver to take dangerous risks.

The treatment of near drowning falls into two phases:

• Restore breathing and heartbeat

• Call for assistance from qualified medical personnel

Regardless of the mildness or severity of a near drowning case, all victims should be hospitalised as quickly as possible. The occurrence of pulmonary oedema (accumulation of fluids in the lungs) pneumonia, and other complications may be delayed for many hours after the incident and proper medical observation is essential. Subsequent to resuscitation while awaiting transportation to medical facilities, the patient should be kept warm and rested.



4.7 BAROTRAUMAS

Emergencies discussed in this section are those which arise out of the nature of the diving environment specifically.

4.7.1 Squeeze

Basically, squeeze barotrauma is caused by a lack of pressure equalisation between parts of the body or between the body and diving equipment. It normally occurs during descent. Squeeze may be categorised by location and / or cause as follows:

• Middle-ear squeeze, caused by blocked Eustachian tube.

• External-ear squeeze, caused by a hood or other piece of equipment covering the external ear passage.

• Lung (thoracic) squeeze, which may happen when the air in the lungs is compressed to less than residual volume. This could happen in an extremely deep breath hold (free) dive.

• Body squeeze, (with deep-sea diving dress), caused by a failure of the air supply to balance water pressure; can be precipitated by a fall into water of greater depth, or by the malfunction or maladjustment of supply and exhaust valves, or by the absence or failure of the safety air non-return valve.

• Face-mask squeeze, caused by a failure to equalise air in the mask by nasal exhalation, or with full-face mask, by malfunction or the air supply or the valving.

• Suit squeeze, normally occurs in dry-type suits in which a pocket of air becomes trapped under a fold or fitting and pinches the skin in the fold area.

4.7.1.1 Treatment

Squeeze may be relieved by the following procedures:

1 Stop descent.

2 If efforts to equalize pressure fail, ascend to shallower depth.

3 If further efforts to equalise pressure fail, abort the dive.

4 If an ear drum rupture is suspected, send down the Standby diver to assist.

5 Report any physical injury to the medical officer for appropriate treatment.



4.7.2 Gas Expansion and Reverse Squeeze

Occasionally, a diver may experience various types of internal gas expansion. For example, in rare instances, a middle ear or sinus that has equalised on descent may block on ascent, trapping a pocket of gas. Slowing the rate of ascent will usually permit the gas to escape without additional complications.

A more common condition results from the generation of gas in the intestines during a dive, or from the swallowing of air which becomes trapped in the stomach. These pockets of gas will usually work their way out of the system through the natural vents. If not, and if pain begins to pass the stage of mild discomfort, ascent should be halted and the diver should descend slightly until the pain is relieved. He should attempt to belch or release the gas anally – with a caution, however, over-zealous attempts to belch may result in swallowing more air.

Most intestinal gas expansion can be avoided by a few simple precautions – do not dive with an upset stomach or bowel, avoid eating foods which are likely to produce intestinal gas and avoid swallowing air during a dive.

4.7.3 Round Or Oval Window Rupture

The round and oval windows are membranes which separate fluid in the inner ear from the middle ear. Symptoms of round or oval window rupture of the ear may become evident on the bottom or after the diver reaches the surface. Usually the diver will have had difficulty clearing his ears during descent but symptoms may arise for no apparent reason. The diver may have ringing or buzzing (tinnitus) in the affected ear, hearing loss, vertigo, disorientation or unsteadiness.

Any or all symptoms of round or oval window rupture may follow dives with depth dive profiles which could give rise to inner ear decompression sickness or arterial gas embolism for which recompression is the only appropriate treatment. Differentiating between these causes may be impossible. If round or oval window rupture is the true cause of symptoms recompression will not usually give relief (and can make the problem worse) and no CNS symptoms other than those which refer to the inner ear will be present.

4.7.3.1 Treatment

A diver suspecting this injury must surface immediately. Once on the surface, it is important to prevent further fluid loss [from the inner ear] by keeping still and upright, and avoiding exertion. Do not allow the patient to do the Valsalva manoeuvre.

NOTE: Permanent damage may be avoided by administering 100% oxygen and seeking immediate specialist medical attention via a diving doctor.



4.8 MEDICAL EMERGENCIES REQUIRING RECOMPRESSION

4.8.1 Diagnosis1

4.8.1.1 Decompression illness

Decompression illness is the term currently being recommended to describe all forms of decompression related problems regardless of the mechanism that has led to the condition. The term includes the conditions known as “decompression sickness” (see paragraph 4.8.1.2) and “arterial gas embolism” (see paragraph 4.8.1.3). This new terminology has arisen as a result of the difficulty encountered in trying to elucidate the mechanism of illness in many cases, the fact that mixed pictures often occur and current treatment recommendations do not differentiate between decompression illness arising from different mechanisms. The description “decompression illness” should be qualified by the part of the body affected, the severity and its timing, e.g. ‘severe progressive spinal cord decompression illness arising within a few minutes of surfacing’.

The signs and symptoms listed below are subdivided into the categories of decompression illness previously usually referred to as this older terminology remains in current use.

4.8.1.2 Decompression sickness

Symptoms and signs of decompression sickness usually appear within a few hours of diving, but onset may be delayed for 36 hours or more. Any body system or part may be affected to a degree from apparently minimal to severe and life threatening.

Untreated, the diver’s condition may deteriorate with time, and additional new symptoms may develop. Feeling generally unwell or unexpectedly lethargic are common early symptoms that may precede more specific symptoms.

Upon examination, many divers suffering decompression sickness will have signs of spinal cord, nerve or cerebral disease which may not have been reported initially. Careful neurological examination (See section 7.1.5 in Annexe F and / or the DOF Subsea Decompression Illness Treatment Package) is therefore important in all cases. This examination may be conducted in the chamber, after treatment has commenced, if appropriate.

Some of the possible symptoms and signs of decompression sickness include skin rash, pain (anywhere), tingling sensations, numbness, weakness or paralysis, difficulty passing urine, visual disturbance, mental slowness, confusion, convulsions or unconsciousness, giddiness, loss of balance or co-ordination, headache, nausea, vomiting and breathing difficulty.

1 Annex G, AS/NZS2299.1: 2007.



4.8.1.3 Arterial gas embolism (AGE)

This usually presents within twenty minutes of a dive and commonly follows a rapid ascent. It can occur following ascents of as little as one metre, and significant bottom time is not required.

Any loss of consciousness or rapid onset of neurological or cardiac problems following a dive should be treated as AGE. The sudden onset of any symptoms of cardiac problems should be similarly treated.

Although symptoms of pulmonary barotrauma are not necessary for the diagnosis of AGE, all patients suffering pulmonary barotrauma should be carefully examined to exclude any neurological problem that would indicate the complication of AGE. Pulmonary barotrauma may be suggested by breathlessness, difficulty breathing, pain in the chest, cyanosis (blueness) or coughing of blood-stained sputum.

NOTE: Arterial gas embolism (AGE) is also sometimes called air embolism or cerebral arterial gas embolism (CAGE).



4.8.2 First Aid

4.8.2.1 100% Oxygen

The rapid institution of 100% oxygen breathing pending recompression will often alleviate symptoms and improve the final outcome of treatment, although improvement on oxygen does not remove the necessity for recompression.

It is important to ensure that the gas breathed by the lungs contains as near as possible to 100% oxygen as can be delivered by the resuscitator specified in paragraph 7.4.8 of the DOF Subsea DOM.

A tight fitting oral nasal face mask, or mouthpiece and nose clip supplied by a demand air supply device or oxygen reservoir bag is necessary to prevent dilution of the oxygen by atmospheric air. Standard disposable medical oxygen masks or nasal catheters are unsuitable.

Oxygen therapy at atmospheric pressure can be conducted for many hours before pulmonary oxygen toxicity becomes a problem. The onset of central chest pain or other indications of this complication may require cessation of oxygen therapy pending medical assessment.

4.8.2.2 Position

Whenever serious decompression illness is suspected, the patient should be made comfortable, lying horizontally. If the patient is not fully conscious, the patient’s airway should be protected, e.g. by lying the patient on the side (lateral or coma position).

The steep (30°) head down position that has sometimes been recommended is extremely uncomfortable and risks congestion and swelling of the brain and regurgitation of stomach contents. It should not be used for decompression illness routinely.

Some anecdotal case histories suggest that an initial period of head down position may, however, be beneficial in some serious cases of decompression illness due to arterial gas embolisation. In cases where major neurological or cardiac symptoms arise within 15 min of surfacing, a trial of head down position may be beneficial provided that is compatible with maintenance of the patient’s airway, and administration of 100% oxygen. The head should be lower than the heart which should be lower than the abdomen and pelvis. The legs should not be elevated any more than the rest of the body.

This position, if tried, should not be maintained if there is no response and, even if there is useful response, the patient should be returned gradually to a level position within 15 min. There have been reports of severe and even fatal relapses occurring when AGE patients have sat or stood up.

No patient possibly suffering from AGE should therefore be allowed to sit or stand up before recompression unless they have been stable and walking around already.



4.8.2.3 Basic Life Support

This should be instituted along usual guidelines if required.

4.8.2.4 Other therapy

Administration of fluids is useful. Intravenous fluids are preferred, however, oral fluids may be offered to the conscious patient without abdominal problems. Plain water is preferred, and fluids containing alcohol and caffeine should be avoided.

Urinary catheterization will be necessary for patients who cannot pass urine, including patients with severe spinal or cerebral decompression illness, and those who are unconscious.

Pneumothorax should be treated by intercostal drainage before decompression can occur during therapeutic recompression therapy.

4.8.3 Recompression Therapy

Recompression is the definitive treatment for decompression illness. Modern therapy requires the use of oxygen in a suitable two-compartment chamber (see DOF Subsea DOM section 7.3).

The initial treatment for all cases of decompression illness resulting from air diving operations shall be in accordance with a widely recognized and industry-approved therapeutic recompression treatment table. Such a Table is the USN Table 6 reference 2.6.5).

The advice of a medical practitioner appropriately trained in underwater medicine and therapeutic recompression should always be sought, and should be considered mandatory in the following situations:

• Any case where symptoms do not rapidly and completely resolve.

• Any case which continues to deteriorate or relapses during treatment in accordance with a therapeutic table.

• Where pressurization equivalent to greater than 18 m (60 ft) depth of seawater is considered.

• Where symptoms recur following initial treatment.

Therapeutic recompression should only be performed by a dive supervisor, a medical practitioner appropriately trained in underwater medicine or, if neither of the above is available, a person (approved by the DOF Subsea Operations Manager) competent in compression chamber operations. The person supervising therapeutic recompression should seek advice from a medical practitioner experienced in this field.



4.8.4 Recompression Treatment

When the diver has received inadequate decompression or falls victim to gas embolism, the first treatment procedure is to return the diver to a pressurised environment where the expanded gases will be recompressed to a manageable volume. This will relieve any local pressure caused by the bubbles, will restore normal blood flow and will frequently relieve the patient of many, if not all, of the subjective symptoms. After recompression treatment is underway, additional treatment may be administered.

Certain facets of recompression treatment have been previously mentioned, but they are so important that they cannot be overstressed:

• Treat promptly and adequately.

• Do not delay treatment for the arrival of medical personnel.

• The effectiveness of treatment decreases with the length of time between the onset of symptoms and the treatment.

• Do not ignore seemingly minor symptoms. They can quickly become major.

• Follow the treatment table accurately and completely.

• If a symptom, or group of symptoms, seems to be relieved, do not assume that the treatment is finished. Follow the tables to completion, and keep the diver in the immediate vicinity of the chamber (or the diving station) for at least 6 hours following recompression and within one half hour travel time to the chamber for 24 hours.

• Flying after diving (refer to DOF Subsea DOM section 8.4.1).

4.8.5 No Recompression Chamber

In the event that the diving facility is not equipped with a recompression chamber, the Diving Supervisor must;

• Place the person on 100% O2 if possible.

• Transport the patient to the nearest recompression chamber for treatment.

Administration of fluids is useful. Intravenous fluids are preferred however oral fluids may be offered to the conscious patient without abdominal problems. Plain water is preferred, and fluids containing alcohol and caffeine should be avoided.

Urinary catheterization will be necessary for patients who cannot pass urine, including patients with severe spinal or cerebral decompression illness, and those who are unconscious.



4.8.6 Decompression & Recompression Treatment

DOF Subsea shall only use United States Navy Table 6 for any decompression related incidents.

A separate Decompression Illness Treatment Package in accordance with the DOF Subsea DOM Annexe E and this Annexe (A), which shall be kept on all dive sites, shall be utilised for the treatment of decompression illness.



5.0 NON-PRESSURE RELATED DIVING EMERGENCIES

5.1 FIRE EMERGENCIES

All personnel should familiarise themselves with local rules when embarking on the vessel / Facility . In particular, they should locate exit routes from their place or work, and the position of the nearest fire alarms.

5.1.1 General Fires

1 The person discovering a fire shall raise the alarm as detailed by the Site Fire Instructions.

2 The Diving Supervisor shall cease all operations and shall, if deemed necessary, follow the flow chart for smoke and fumes.

3 Once the alarm has been raised, fire-fighting action shall be initiated to control and overcome the fire.

4 If the fire cannot be contained and or overcome, the person in charge must be informed and all persons on the site shall go to their muster stations.

5 At the muster station, assistance shall be provided as required.

5.1.2 Smoke / Fumes / Gas Procedure

1 The person discovering the presence of smoke, fumes or gas shall immediately raise the alarm.

2 The Supervisor shall assess the situation to determine if diving may continue.

If diving cannot continue, the Supervisor shall carry out the following:

3 Don the Supervisors breathing mask.

4 Switch the divers to HP air.

5 Switch the standby diver to HP air.

6 Recover the diver as per DOF Subsea Decompression Procedures.

7 Move to a safe place.

8 If breathing sets are not available for the remainder of the crew they shall move to a safe place.



5.1.2.1 Smoke / Gas / Fumes Flow Chart

Fumes / Smoke / Gas

Can Continue?

Go To A Safe PlaceRecover Diver

Remainder Crew Fit BA Sets or Go To A Safe

Place

Standby Diver to HP Air

Diver to HP Air

Dive Supervisor Don BA Set

Cease All Operations

Continue

Assess Situation

Raise Alarm

YES

NO



5.1.3 Chamber Fire - General

The risk of fire is increased in air under pressure, and further increased when oxygen is being used. The drill for using the DDC provides for periodical ventilation of the chamber during operation to prevent build up of oxygen.

The DDC shall be kept thoroughly clean and free from all flammable material when in use. This includes matches, cigarettes, lighters, flammable liquids, nylon fabric, oil, grease etc.

5.1.3.1 Action in the event of a fire

1 Secure oxygen.

2 Attempt to put out the fire with the hyperbaric fire extinguisher, blankets, etc.

If unsuccessful:

3 Decompress chamber rapidly.

4 Remove the occupants and extinguish the fire.

5 Recompress the occupants at the earliest possible moment back to depth existing when the fire broke out.

NOTE: Should it suddenly become necessary to reduce the DDC pressure because of fire, the Diving Supervisor must bear in mind the physiological risks involved and weigh them against the risk of leaving the occupant in the chamber. It is not possible to lay down any hard and fast rules as there are an infinite number of circumstances that may affect a decision. Generally speaking, rapid decompression is likely to cause serious decompression sickness or air embolism. It is absolutely essential that the occupants of the chamber are put under pressure again as soon as possible.



5.1.3.2 Chamber Fire Flow Chart

Fire Extinguished

Secure Oxygen

Attempt To Extinguish Fire

Fire In Chamber

Decompress Chamber Rapidly

Recompress Occupants And Treat

Accordingly

Continue Treatment or Decompression

Remove Occupants and Extinguish Fire

YES

NO



5.2 LOSS OF AIR / GAS PROCEDURE

On advice from the diver that he has lost air and is on bailout, the Supervisor shall carry out the following:

1 Instruct the diver to go to the stage and go on the stage emergency air bottle as well as prepare himself to leave the bottom.

2 Assess the situation to determine if the problem can be fixed immediately.

3 If yes, fix the problem and reassess if divers should continue diving.

4 If no, abort the dive.

5 If the diver requires assistance, the standby diver shall be jumped to assist.



5.2.1.1 Loss Of Air/Gas Procedure Flow Chart

Can Problem Be Fixed Immediately?

Can Continue?

Diver Advises Lost Air/Gas - "On Bailout"

Assistance Required?

Investigate Cause

Continue

Return To Surface

Assist Retrieval

Jump Standby Diver

Abort Dive

Fix

Assess Situation

Dive Supervisor - "Prepare to Leave Bottom"

NO

YES

YES

NO

YES

NO



5.3 Lost Communications Procedure

Person Actions

Supervisor

Immediately communication is lost with the diver • Request line signals, “Are you OK?” • If available flash hat light to attract divers attention. The

diver should give thumbs up in front of camera! • Alert the standby diver and check his communications. • Determine if the diver is still breathing by checking the

diver’s LP supply gauge. • If the diver is not breathing, instruct the standby diver to

jump to rescue the diver. • Ensure the standby diver follows the diver’s hose to the

diver and not a down line or stage.

Supervisor If the diver is breathing, the following shall apply • Check connections on the radio. • If communications are re-established, continue diving. • If communications are still lost, change radio and re-

establish communications. • If communications are re-established, continue diving. If communications cannot be re-established, instruct the standby diver and dive crew to use line signals and jump the standby diver.



5.3.1.1 Lost Communications Flow Chart



5.4 LAUNCH AND RECOVERY SYSTEM FAILURE PROCEDURE

On arrival at any dive site, unless planned previously, an alternate means of diver recovery shall be planned and instigated. Refer Section 1.3.7, LARS Operation for details.

If the LARS fails, assess the situation and advise the diver that the planned alternate method of recovery shall be implemented.

• If the problem can be rectified without placing the diver in danger, rectify the problem and continue diving.

• If not, implement the alternate means of diver recovery and retrieve the diver to the surface.

5.4.1.1 Launch And Recovery System Failure Flow Chart

LARS Failure

Can Problem Be Rectified?Rectify and Continue

Abort Dive Retrieve Diver

Advise Diver of Alternate Recovery Method

Assess Situation. Advise Diver

YES

NO



5.5 ENTANGLED DIVER PROCEDURE

Upon becoming entangled, the diver shall immediately inform the Supervisor and attempt to untangle himself. If successful, diving shall continue providing it is safe to do so.

If the diver cannot free himself, the standby diver shall be deploy to assist in freeing the diver.

The standby diver shall follow the diver’s hose to the diver or to the point of entanglement.

Once the diver has been freed, the Supervisor shall determine if diving shall continue. If yes, the standby dive shall return to the surface. If no, both divers shall be retrieved.

5.5.1.1 Entangled Diver Flow Chart

Can Diver Free Himself?

Continue Dive?

Entabgled Diver

Retrieve Both Divers

Continue

Retrieve Standby Diver

Jump Standby Diver

Continue YES

NO

YES

NO

Entangled Diver



5.6 INJURED / UNCONSCIOUS DIVER PROCEDURE

If the diver reports an injury that does not require assistance, the diver shall be recovered to the surface. If assistance is required, the standby diver shall be immediately deployed to assist.

1 Place standby diver on HP air.

2 Upon reaching the injured or unconscious diver, the standby diver shall firstly ensure there is no danger to himself and then shall check the diver’s response.

3 If the diver is unconscious, regardless of sign of breathing, the standby diver shall free flow the diver’s mask and prepare both divers to leave the bottom.

4 Care shall be taken to ensure that an unconscious diver’s head is back during ascent to assist in breathing.

5 On ascent the standby diver shall press gently but firmly on the diver’s diaphragm to assist the expulsion of air from the lungs due to expansion during ascent.

6 Once the diver has been recovered to the surface, DRABC (see section 5.8) shall commence immediately. This may be in a stage, on a landing or on the back deck of a vessel.

7 Once the diver is stabilised, the situation shall be reported by following the External Communications flow chart outlined in the Emergency Procedures.



5.6.1.1 Injured / Unconscious Diver Flow Chart

Diver Reports Injury / No Response From Diver

Open Free Flow Mask

Implement DRABC Procedure - See Flowchart

Recover to Surface

Retrieve To Deck

Check Response

Jump Standby Diver

Abort Dive

Place Standby Diver on HP Air

Assistance Required?

External Communications

Flow Chart

NO

YES



5.7 FIELD HAZARDS / INCIDENTS PROCEDURE

Once any hazard / Incident has been raised and reported to the Dive Supervisor, the Dive Supervisor shall establish if diving may continue.

Typically these field hazards / incidents may include but not be limited to:

• Vessel / Facility integrity (collision)

• Fire / explosion

• Man overboard

• Security breach

• Medical (injury and / or evacuation)

• Non-Diving related equipment damage

If no, all operations shall cease and the dive team shall provide assistance as requested by the P.I.C. (person in charge).

5.7.1.1 Field Hazards Flow Chart

Field Emergency

Provide Assistance As

Required

Cease All Operations

Continue

Search & RescueOther Vessel Emergencies

Can Diving Continue?YES

NO



5.8 DANGER RESPONSE AIRWAY BREATHING CIRCULATION FLOW CHART

Documents

DOF Subsea DOM-A-Rev 0 Air & Emerg Proc