Maiine Fluid Power Application

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Marine Fluid Power Application


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Learning Objective:Learning Objective: Acquire generalAcquire general

knowledge on the common deck machineriesknowledge on the common deck machineriesonboard ships.onboard ships.

Specific Objectives:Specific Objectives:

At the end of this module, the participants shouldAt the end of this module, the participants should

be able to:be able to: State the various deck machineries and theirState the various deck machineries and their

usesuses Describe windlass operationDescribe windlass operation

Describe winch operationDescribe winch operation Describe deck crane operationDescribe deck crane operation Sketch a typical hydraulic systemSketch a typical hydraulic system


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APPLICATION

Deck Hull machineries-> Windlasses, Winches,Capstans, Cranes, Lifeboats, Anchor

Hull machineries ->Fins Stabilisers, Thrusters

Waterways activities->Dredgers, navigation lock,

Marine system fluid transport-> Ballast water, Offshore-> drilling

Hydraulics used in many applications: Steering/control systems (rudder, planes)

Deck machinery (anchor windlass, capstans, winches) Masts & antennae on submarines Weapons systems (loading & launching) Other: elevators, presses


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A General Cargo Ship


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WindlassDuty is to lift the anchors and assist inwarping the ship.

Size and power depends upon the massesof anchors and cable, and full load hauling.

It may be powered by steam engine orelectric motors.


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Windlass


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Windlass


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Windlass


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Windlass


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Chains .


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Winch WindlassesUtilizes a forward mooring winch to drive awindlass unit thus reducing number of primemovers required.

Port and starboard units are normally inter-connected both mechanically and for powerin order to provide stand-by drive.

It also utilize the power of both winches onthe windlass should this is required.


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Winch Windlasses


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Winch


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Winch drive


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Capstan A vertical-barrelled, rotative device arrangedfor either hand operation or hand and power

operation with pawls at its base to prevent it

from reversing.

Generally used for warping or pulling objects

in a horizontal direction.


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Capstan


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CARGO HANDLING

The duty of a deck winch is to lift and lower a load by means of afixed rope on a barrel, or by means of whipping the load on the warpends; to top or luff the derricks, and to warp the ship.

In fulfilling these duties it is essential that the winch should becapable of carrying out the following requirements:

(a) lift the load at suitable speeds; (b) hold the load from running back;

(c) lower the load under control; (d) take up the slack on the slings without undue stress;

(e) drop the load smartly by answering the operatorsapplication without delay;

(f) allow the winch to be stalled when overloaded, and to start upagain automatically when the stress is reduced;

(g) have good acceleration and retardation:


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CARGO HANDLINGIn addition when the winch is electrically driven the requirements are:(a) prevent the load being lowered at a speed which will damage the motor

armature;

(b) stop the load running back should the power supply fail;(c) prevent the winch starting up again when the power is restored until the

controller has been turned to the correct position.

Hydraulic winch systems are now quite common but electric drives for cargo winches

and cranes are most widely used.

For the conventional union purchase cargo handling arrangement or for slewingderrick systems handling loads up to 20 tonne, standard cargo winches are normallyused for hoist topping and slewing motions, the full load duties varying from 3-10tonne at 0.65 to 0.3 m/sec

For the handling of heavy loads, although this may be accomplished withconventional derrick systems using multipart tackle, specially designed heavy liftequipment is available.

The winches used with these heavy lift Systems may have to be specially designedto fit in with the mast arrangements and the winch duty pull may be as high as 30tonne.


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Cargo winches It is usual to select the number and capacity of and to group the

winches in such a way that within practical limits all hatches may be workedsimultaneously and having regard to their size (and the hold capacity beneath

them) work at each is carried out in the same period.

Reduction of the cycle time during cargo handling is best accomplished by the useof equipment offering high speeds say from 0.45 m/see at full load to 1.75 m/seclight, the power required varying from 40 kW at 7 tonnes to 20 kW at 3 tonnes; thisfeature is available with electro-hydraulic and d.c. electric drives as they offer anautomatic load discrimination feature.

However, the rationalisation of electrical power supply on board ship has resultedin the increased use of a. c. power and the majority of winch machinery nowproduced for cargo handling utilises the polechanging induction motor.

This offers two or more discrete speeds of operation in fixed gear and amechaincal change speed gear is normally provided for half load conditions.

Normally all modern cargo handling machinery, of the electric or electrohydraulictype is designed to fail safe.

A typical example of this is the automatic application of the disc brake on anelectric driving motor should the supply fail or when the controller is returned to the

OFF position


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Derricks


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Derrick A lifting device composed of one mast or pole

which is hinged freely at the bottom.

It is controlled by (usually 4) lines powered bysome such means as man-hauling or motors,so that the pole can move in all 4 directions.

A line runs up it and over its top with a hookon the end, like with a crane.


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Derrick


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Derricks Most older ships and some recent ones use winches in conjunction

with derricks for working cargo.

The derricks may be arranged for fixed outreach working or slewingderricks may be fitted.

A fixed outreach system uses two derricks, one topped to a positionover the ships side and the other to a position over the hold.

The disadvantages of the fixed outreach systems are

that firstly if the outreach requires adjustment cargo work must beinterrupted, and secondly the load that can be lifted is less than thesafe working load of the derricks since an indirect lift is used.

Moreover considerable time and man power is required to prepare aship for cargo working.


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Union purchase rig

The commonest arrangementadopted, known as Union Purchaserig.

The main advantages of the system

are that only two winches arerequired for each pair of derricks and

it has a faster cycle time than the

slewing derrick system.


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Slewing derrick

The slewing derrick system,

one type of which has the

advantages that there is no

interruption in cargo work foradjustments and that Cargo can

be more accurately placed in the

hold; however in such a system

three winches are required for

each derrick to hoist luff and

slew.

D k C


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Deck Crane

Cranes have replaced derricks on modern ships.

Positioned between holds, on a platform which can berotated through 360 degrees.

Three separate drives of hoisting motor for lifting,motor for raising or lowering the jib, and slewing

motor for rotating the crane.

Operating medium may be hydraulic or electric.

Double gearing is a feature of most designs providing ahigher speed at lighter load.

For heavy load operation, twinning with a single operator

using a master and slave control system in the two cranes.


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Deck Crane


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Deck Crane


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Deck cranes

A large number of ships are fitted with deck cranes.

These require less time to prepare for working cargo thanderricks and have the advantage of being able to accuratelyplace (or spot) cargo in the hold.

On container ships using ports without special containerhandling facilities, cranes with special container handling gearare essential.

Deck-mounted cranes for both conventional cargo handling andgrabbing duties are available with lifting capacities of up to 50

tonnes.


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Stulken derrick (Blohm and Voss)

Ships specialising incarrying very heavy

loads however, areinvariably equippedwith special derricksystems such as theStulken

These derrick systems

are capable of lifting

loads of up to 500

tonnes


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Deck cranes motor

Crane motors may rely upon pole changing for speed

variation, Ward Leonard and electro-hydraulic controls are those

most widely used.

One of the reasons for this is that pole-changing motors can only give arange of discrete speeds but additional factors favouring the twoalternative methods include less fierce power surges since the Ward.Leonard motor or the electric drive motor in the hydraulic system runcontinuously and secondly the contactors required are far simpler and

need less maintenance since they are not continuously being exposedto the high starting currents of

pole-changing systems


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Deck cranes

Deck cranes require to hoist, luff and slew and separate electric orhydraulic motors will be required for each motion.

Most makes of crane incorporate a rope system to effect luffing andthis is commonly rove to give a level luff where the cablegeometry is such that the load is not lifted or lowered by the actionof luffing the jib and the luffing motor need therefore only be rated

to lift the jib and not the load as well.

Generally, deck cranes of this type use the Toplis three-partreeving system for the hoist rope and the luffing ropes are rovebetween the jib head and the superstructure apex which gives

them an approximately constant load, irrespective of the jib radius.

-


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-hoisting

This load depends only on theweight of the jib, the resultant

of loads in the hoisting ropedue to the load on the hookpasses through the jib to the jibfoot pin


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Deck cranes If the crane is inclined 5 in the forward direction due to heel of the

ship the level-luffing geometry is disturbed and the hook loadproduces a considerable moment on the jib which increases the pullon the luffing rope.

In the case of a 5 tonne crane the pull under these conditions isapproximately doubled and the luffing ropes need to be over-proportioned to meet the required factor of safety.

If the inclination is in the inward direction and the jib is near

minimum radius there is a danger that its weight moment will not besufficient to prevent it from luffing up under the action of the hoistingrope resultant.

Swinging of the hook will produce similar effects to inclination of thecrane.


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Deck cranes

In the Stothert Pitt Stevedore electro-hydraulic

crane the jib is luffed by one or two hydraulic crains.

Pilot operated leak valves in the rams ensure that the jibis supported in the event of hydraulic pressure being lostand an automatic limiting device is incorporated whichensures that maximum radius can not be exceeded.

When the jib is to be stowed the operator can overridethe limiting device.

In the horizontal stowed position the cylinder rods arefully retracted into the rams where they are protectedfrom the weather .


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Deck cranes

Some cranes are mounted in pairs on a common platform which can berotated through 360 .

The cranes operate independently or locked together and operate as atwin-jib crane of double capacity", usually to give capacities of up to 50tonnes.

Most cranes can, if required, be fitted with a two-gear selection to givea choice of a faster maximum hoisting speed on less than half load.

For a 5 tonne crane full load maximum hoisting speeds in the range 50-75 m/min are available with slewing speeds in the range1-2 rev/min.

For a 25 tonne capacity crane, maximum full load hoisting speeds in

the range 20-25 m/min are common with slewingspeeds again in the range 1-2 rev/min.


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Drive mechanism and safety

features

In both electric and electro-hydraulic cranes it is usual to find that thecrane revolves on roller bearings.

A toothed rack is formed on them periphery of the supporting seat anda motor-driven pinion meshes with the rack to provide drive.

Spring-loaded disc or band brakes are fitted on all the drive motors.

These are arranged to fail safe in the event of a power or hydraulicfailure. The brakes are also arranged to operate in conjunction with motor

cut-outs when the crane has reached its hoisting and luffing limits, orif slack turns occur on the hoist barrel.

In the case of the electro-hydraulic cranes it is normal for one electricmotor to drive all three hydraulic pumps and in Ward-Leonard electriccrane systems the Ward-Leonard generator usually supplies all threedrive motors


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Other deck and Hull andmachineries


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Hatch covers


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Hatch covers


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Hatch covers


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Bow Thruster A propulsion device built into, or mounted to,

the bow of a ship or boat to enhance itsmaneuverability.

Bow thrusters make docking easier, sincethey allow the Captain to turn the vessel toport or starboard without using the mainpropulsion mechanism which requires some

forward motion for turning.


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Bow Thruster


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Thruster


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INTRODUCTION

1.Surging

2. Swaying

3. Heaving

4. Rolling

5. Pitching

6. Yawing

1. Surge2. Sway3. Heave4. Roll

5. Pitch6. Yaw

Linear

Rotational


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Fins stabilizer

There is a limit to the extent to which amplitudes ofmotion can be reduced in conventional ship formsby changes in the basic hull shape.

Fortunately, con-siderable reductions in rollamplitudes are possible by other means, roll beingusually the most objectionable of the motions asregards comfort.

In principle, the methods used to stabilize against

roll can be used to stabilize against pitch but, ingeneral, the forces or powers involved are too greatto justify their use.

(a) Active systems


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(a) Active systems

In these systems, the moment opposing roll isproduced by moving masses or control surfaces bymeans of power.

They also employ a control system which senses therolling motion and so decides the magnitude of thecorrecting moment required. As with the passive

systems, the active systems may be internal orexternal to the main hull.

The principal active systems fitted are: Active fins

Active tank system Active moving weight Gyroscope.


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STABILISATION SYSTEMSTABILISATION SYSTEM

Active systems

Active Fins


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Active systems

Active Weights


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Active systems

Active Tanks System

(b) Passive systems


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(b) Passive systems

In these systems, no separate source of power is required and

no special control system. Such systems use the motion itself to create moments opposing

or damping the motion. Some, such as the common bilge keel, are external to the main

hull and with such systems there is an added resistance to

ahead motion which has to be overcome by the main engines. The added resistance is offset, partially at least, by a reduction in

resistance of the main hull due to the reduced roll amplitude. Other passive systems, such as the passive anti roll tanks, are

fitted internally. In such cases, there is no augment of resistance

arising from the system itself. The principal passive systems (discussed presently) fitted are: Bilge keels (and docking keels if fitted) Fixed fins Passive tank system

Passive moving weight system.


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Passive systems

Bilge Keels


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Passive systems

Fixed Fins


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Passive systems

Passive Moving Weight System


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Fin stabilizer


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Fin stabilizer


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Thruster and fins stabilizer

Shiphandling: Twin Screw Ships


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Ship AheadBoth Propellers Ahead

Shiphandling: Tug Tie-Ups


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Single Headline

Simplest Tie-up

Best to allow tug to

push or pull only

Not good if complex tug

maneuvers required.


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TUG BOAT

Svitzer multipurpose tugs Rolls-Royce thrusters and winches


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Svitzer multipurpose tugs Rolls-Royce thrusters and winches

Prime mover ->1,800kW diesel engine. A maximum ahead speed of13.8 knots, an astern speed of 13 knots

Efficient propulsion and impressive maneuverability for the 30.3m-long/228 dwt ASD tugs are provided by twin Ulstein AquamasterUS205CP azimuthing thrusters

manoeuvrability further enhanced by a 200kW Kamewa Ulstein bowthruster.

bollard pull ahead of 66 tons are reported,

towing equipment outfit is based on a Rolls-Royce 30/160 winch forwardand an aft towing hook of 65 tonnes swl capacity. A five tonne capacitycapstan was also provided by Rolls-Royce. The specification allows fire-fighting duties to be undertaken, twin monitors mounted on thewheelhouse roof having a combined output of up to 2,400m3/h.

These valuable additions to its fleet are enabling Svitzer to enhanceservices in all the main ports, assisting tonnage entering and departing.

executes diverse heavy lift transportation and towage services as wellas salvage projects.

A range of over 5,000 nautical miles from the new tugs underwrites acapability to carry out long haul towage tasks, with accommodationarranged for up to six crew members.


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Navigation lock and flood protection


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Dredgers


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Open Loop System

The system takes oil from the tankand pumps it into the hydraulic motor.

A control valve is positioned in parallelwith the motor.

When it is open, the motor isstationary; when it is throttled or closedthe motor will operate.


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Open Loop System

The exhaust oil returns to the tank

Commonly used in low pressure

system and are simple in design as wellas reliable.


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Open Loop System


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Closed Loop System

In the system, the exhaust oil isreturned direct to the pump suction.

Since the oil does not enter an opentank, the system is considered closed.

Suitable for medium pressure system inmarine application .


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Closed Loop System


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Centralized Hydraulic Power System


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Centralized system arrangement


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Global Explorer ROV

Highly maneuverable 3,000 m depth

capability

High DefinitionVideo Suction samplers

for organisms Portable for use on

any ship


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MOCNESS Midwater Trawl

Standard samplingsystem formacroplankton andfish

10 m2

trawl net 6 nets for depth-stratified samples

Monitorstemperature,

salinity, depth andoxygen


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Ballast water


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Electrohydraulic Speed Gear


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Control of System

Remote control Normal method

Control from bridge

Emergency Take local control

Manually position control surface/rudder


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Advantages Convenient power transferConvenient power transfer Few moving parts

Low losses over long distances

Little wear

FlexibilityFlexibility Distribute force in multiple directions

Safe and reliable for many uses

Can be stored under pressure for long periods Variable speed controlVariable speed control Quick response (linear and rotary)


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Disadvantages

Requires positive confinement (to give

shape)

Fire/explosive hazard if leaks or rupturesFire/explosive hazard if leaks or ruptures

Filtration critical - must be free of debris

Manpower intensive to clean up


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Summary

Operations: Mooring, Anchoring, LoadingDischarging etc.,

Machinery Functions for operations

Prime movers: Steam, Electric & HydraulicWinches, Windlasses, Cranes etc.,

Specific Topics: Bow thrusters, Deck Hydraulics


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Questions?

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Maiine Fluid Power Application