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Australian Marine Complex – Common User Facility Floating Dock

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AMC Floating Dock – Western Australia IESIS University Lecture 21

st September 2010

By David M. Westmore, B.Sc.(Hons), C.Eng., MRINA, FIES,

Managing Director, Clark & Standfield Ltd, Designers of the Floating Dock.

1. Introduction In the year 2000, the Government of Western Australia commissioned the construction of a new common user fabrication and maintenance facility close to the capital city of Perth and its associated seaport, Fremantle. The purpose of the facility was to enable local industry to target large-scale projects in a number of market sectors and to provide equal access to any company, state, national or international, wishing to undertake such projects in the area. The area housing the facility is known as the Australian Marine Complex (AMC) and was already home to much of the shipbuilding and repair business in Western Australia, although docking capacity was restricted to the 8000 tonnes shiplift. This paper looks at the background to the requirements for a floating dock to enhance the AMC facilities, how the dock design evolved and its subsequent construction.

2. Australian Marine Complex – Common User Facility As part of the Western Australian Government’s strategy to attract industry into the state, the Australian Marine Complex was set up, located south of Fremantle. It is an integrated industrial estate servicing the defence, marine, resource and petroleum sectors with about 100 businesses located there. The Australian Marine Complex incorporates a Common User Facility (CUF) originally constructed with fabrication halls, workers amenities, project offices, wharves, hardstand, cranage, warehousing and reticulated services, covering an area of 40 hectares (approx 100 acres). It is available to multiple users and has injected more than $106million of work into the local economy since its completion in 2003.

By using the CUF, companies can hire the facilities to undertake a particular project thus avoiding the burden of cost associated with creating facilities for projects, which they may not necessarily win or for which they have no requirement when the project is completed.

The Royal Australian Navy, in particular, expressed an interest in moving maintenance operations from its base close to the facility with afloat repairs and conversions being transferred to the CUF in 2005. Around the same time, other naval requirements became apparent, particularly the need to refit submarines in a specially constructed maintenance hall.

The facility is managed on behalf of the Western Australian Government by AMC Management (WA) Pty Ltd who also project managed the upgrading of the AMC-CUF facilities, including the floating dock.

3. Upgrading AMC CUF Facilities The increase in CUF activity led to feasibility studies and business planning for further site developments, which included additional wharfage, power upgrades, dredging and buildings. In addition to these, an increase in docking and launching capacity over the existing 8000 tonnes was considered. Future RAN requirements were key issues for this increase since its West Coast (Indian Ocean) operations have been steadily increasing over the past 15 years.


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The need for such facilities was considered essential to take account of two major defence programmes:

1) The Australian Submarine Corporation (ASC) was investing $35million in maintenance and upgrade facilities at the AMC to enable it to meet contracts to service the Royal Australian Navy’s Collins-class submarines based at HMAS Stirling. This required the provision of shore transfer facilities at the AMC to move the vessels to a purpose built maintenance hall.

2) The desire for Western Australia to be in a strong position to bid for the $2billion Amphibious

Ships (LHD) construction and through-life support projects for the Royal Australian Navy. This would require launching and drydocking facilities at the AMC for the LHD.

An investigation was carried out into graving docks, marine railways, shiplifts and floating docks to provide the drydocking and launching requirements. The floating dock option was found to be the most versatile and cheapest and in 2006 the Western Australian Government decided to proceed with a $174million infrastructure upgrade at the Australian Marine Complex (AMC) in Henderson, which is expected to create up to 3,000 jobs over the next 10 years. It includes the construction of a floating dock, a new transfer system, dredging of a 17m-deep basin to accommodate the floating dock, an extension of the existing eastern wharf, site works and electricity upgrades. According to the WA Government, the investment in the 100m floating dock alone is expected to inject $3billion into Western Australia’s economy over the next 25 years from naval contracts, as well as up to $175million per annum in other projects. In addition, the upgrade would provide the opportunity for WA to bid for a range of other maintenance and construction projects across the marine, defence and resources sectors.

4. Floating Dock Requirements To meet the major defence programmes, the floating dock was required to carry out the following primary functions:

1) Shore transfer of 18,000 tonne new build LHD (Landing Helicopter Dock). 2) Shore transfer of 3500 tonne Collins Class submarines and ANZAC frigates. 3) Docking of a 24000 tonne LHD when complete (without shore transfer).

In addition, to minimise the impact on the civil works, the docking evolutions had to be carried out in way of a deep sink basin in the harbour. Whilst the submarine requirements were confirmed with the Australian Submarine Corporation proceeding with the construction of their new facilities, the LHD programme was more problematic – the need for LHD launch facilities would not be known until much later.

5. Floating Dock Concept Clark & Standfield were appointed to design the dock and, to meet the requirements, a two-part dock was developed. One section (Dock 1) was designed and built to facilitate the docking and land transfer of Collins class submarines whilst the other section (Dock 2) was designed, but will only be built in the event of the Government proceeding with construction of the LHDs in Western Australia. This concept is illustrated in Figure 1.


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DOCK 2 = 132000 DOCK 1 = 990001650

232650

LHD = 230000

DISPLACEMENT 18000 TONNES

ARLEIGH BURKE CLASS DISPLACEMENT 8500 TONNES

LHD BLOCKING LENGTH 195m

DOCK 1 = 99000DOCK 2 = 132000

ARLEIGH BURKE CLASS

ANZAC CLASS COLLINS CLASS COLLINS CLASSANZAC CLASS

Seaward End Shore End

Figure 1 – Floating Dock and Docked Vessel Combinations

The dimensions of the combined dock to accommodate the LHD shore transfer at the transfer draft of 4.50m were such that the dock would also be able to accommodate Panamax size vessels up to 28000 tonnes when at docking draft of 5.05m. In addition, dock 2 could accommodate an air warfare destroyer such as the Arleigh Burke Class: one of the vessels being considered by the Royal Australian Navy at the time. The requirements are summarised in Table 1.

Floating Dock Configuration Vessels Docking Weight

(tonnes) Shore Transfer

Dock 1 Collins Class Submarines Anzac Frigates

3000 3500

Yes Yes

Dock 2 Collins Class Submarines Anzac Frigates Arleigh Burke or Similar

3000 3500 8500

No No No

Dock 1 + 2 (Joined by splice plates)

LHD Launch 18000 Yes

Dock 1 + 2 (Joined by Rocking Joint)

LHD Complete Panamax

24000 28000

No No

Table 1 - Principal Requirements The pontoon deck was kept level without camber for the following reasons:

a) easier to adjust blocking arrangements without the need to readjust for the dock camber b) keeps pontoon deck parallel to quayside making shore transfers easier c) simplifies construction.

Although the width of dock 1 is large for its length by conventional standards, as it is designed on a combined dock basis, it provides additional flexibility for the use of multi hull dockings, particularly with one of the local shipbuilding companies undertaking ever larger multihull constructions. Furthermore,


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the developing oil and gas industry off the West Australian coast will also benefit. The extra width also enables the docking of more than one vessel transversely. The flying gangways provide access from one sidewall to the other at deep sink but will be in the open position during transfer ashore. Unusually, the flying gangways are also designed to hinge partway back into the dockwell to facilitate access to a docked submarine’s casing to permit emergency evacuation during a docking evolution. A cross-dock duct is also provided from one sidewall to the other through the ballast tanks. This permits access by personnel from one sidewall to the other as well as for cross-dock cables, utility piping, etc. Many docks have sloping ends to their sidewalls to provide a convenient access route to the top deck as well as saving on steel and pumping. However, because of the need to provide connections between the two docks and the need to provide a grounding point, the end sidewalls were kept rectangular. Access to the dock was therefore by means of outboard stairways from the top deck passing through sally ports in the sidewall to the pontoon deck. The control house is provided at the shore end extending beyond the sidewall. This allows good oversight during docking operations as well as the grounding arrangements for shore transfer.

6. Combined Dock Operations Although each dock is capable of independent operation, there will be occasions when the docks are required to operate in combination for larger vessels, typically when the vessel length exceeds about 55% of the combined dock length. Two methods are provided: Method 1 Rocking Joint (Ref Figure 2).This consists of six castings on each sidewall. Three resist

shear upwards and three resist shear downwards. The six castings nest into 6 similar castings on the connecting dock opposite and restrain the dock vertically but allow the docks to rotate longitudinally so that no bending moments transfer through the joint. The docks are kept together longitudinally by a connection screw between the two docks.

The rocking joint allows the docks to be brought together quickly and easily without the need for welding etc. Longitudinal bending moments can be carried from one dock to the other through the docked vessel and to avoid overstressing the docked ship, the longitudinal deflection of the combined docks is monitored with the ballasting arranged to keep the deflection, and hence bending moments in the ship, to the minimum.

ROCKING JOINT CASTING

DOCK CONNECTION

SCREW

PONTOON DECK

SIDEWALL – AFT END

Figure 2 - Rocking Joint and Dock Connection Screw On Aft End Sidewall (Port shown, Starboard Similar)

TOP DECK SPLICE PLATE

INNER SIDEWALL SPLICE

PLATES

PONTOON DECK

INNER SIDEWALL

DOCK 2

DOCK 1

TOP DECK

Figure 3 - Splice plates on Top Deck and Inner Sidewall. (Splice plates also provided on outer sidewall and at pontoon deck level in way of sidewall).

Method 2 Splice Plates (Ref Figure 3). The docks are brought together using the rocking joints and then welded steel splice plates are added.


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The sidewalls utilise thicker steel in way of the splice plate connections to enable welding/burning off the plates whilst minimising damage that welding/burning may cause to coatings etc. Splice plates are only required for shore transfers as the ability to transfer longitudinal bending moments simplifies the ballasting procedures.

A computerised control system is provided with each dock but arranged such that when operating in a combined mode, the two docks can be fully controlled from one control room.

7. Shore Transfer 7.1 Transfer System The dock was originally designed for a rail transfer system requiring a high degree of accuracy in aligning the dock to the shore rails. This required:

1) a centring spigot to locate into a shore receptacle.

2) grounding cylinders extending into sockets in the grounding pads to hold the dock.

3) grounding cylinders capable of being raised or lowered to accommodate pontoon transverse deflections under load to maintain transfer level accuracy.

Photo 1–SPMT on the Floating Dock with Collins Class Submarine Docking Cradle Eventually it was decided to use SPMTs (Self-Propelled Modular Transporters) instead of a rail system since this provided additional capability to the marine complex for moving heavy loads, including non-dock use. This also increased the flexibility of the dock’s transfer position so that the transfer point no longer required to align with ASC’s maintenance hall which reduced the amount of civil works. The SPMTs are capable of accommodating local variations in ground level up to ±350 mm allowing greater tolerance on the level of the pontoon deck with the quayside during transfer. The SPMTs comprised 512 wheels in 128 axle lines capable of moving modules up to 4000 tonnes (Ref Photo 1). Consequently, the centring spigot and the grounding sockets were not required. A pair of roller fenders were added to the shore end to provide a buffer between the dock and quayside allowing the dock to be manoeuvred along the quayside. A portable roadway consisting of a number of sections was provided on the pontoon deck to align with the cope level and to spread the wheel loads of the SPMTs.


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7.2 Ballasting Arrangements The principle of ballasting/deballasting the dock is to minimise longitudinal deflections and bending moments by ensuring that the net loading on each section of the dock is minimised. Thus for each section, the sum of dock weight, ship weight, and ballast water should be as near as possible equal to the displacement of that section. This applies to both normal docking evolutions and shore transfers. The technique is often called differential ballasting and is used for all large docks to avoid excessive longitudinal strength requirements.

SHIP WEIGHT DISTRIBUTION OVER BLOCKS

Figure 4 – Differential Ballasting to match ship Weight Distribution over Blocks Where a dock is used for shore transfer in tidal areas, the ballasting of the dock needs to take account of both tidal movement and vessel loading. In these circumstances, it can be simpler for the side tanks to compensate for change in displacement due to tide changes and the pontoon tanks to compensate for vessel loading. These side tanks (tidal tanks) require pumps capable of ballasting as well as deballasting whereas ballasting the pontoon tanks would be by free flood only. Although the tidal range at the AMC is in the order of 1.1m, the tides are diurnal and often fairly static throughout the day. This meant that large and/or fast tidal changes would not occur allowing a conventional ballast arrangement (ballasting by free flood and deballasting by pump out) to be used without the need for tidal tanks – small changes could be easily dealt with using a conventional dock ballasting arrangement. 7.3 Grounding System Some docks are completely free floating for land transfer where as others ground the dock to ensure accuracy of dock level. This can be in the form of an underwater grid where the dock is grounded over its full length or by the use of docking ledge/lip where the dock is grounded only at the shore end. It was decided to use a form of the latter methodology with the sidewalls being extended to bear down on the quayside. This gave accuracy of levels whilst minimising the amount of civil works required. To ensure the dock remains at a constant level during the transfer operation, the dock is provided with 4 hydraulic cylinders under the sidewall extensions at the forward end of the dock. These bear on grounding pads consisting of steel plates embedded in the shoreside pavement. The hydraulic cylinders are in line with the outer and inner sidewalls and are cross connected to ensure that the loads are equally distributed, particularly when the pontoon is subject to transverse bending moments.

PORTABLE ROADWAY

LEVEL WITH QUAY

QUAYSIDE

GROUNDING PADS

EXTENSION PIECE

HYDRAULIC CYLINDERS

SIDEWALL

Figure 5 - Grounding System Arrangement


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The system is designed for a combined nominal load of 500 tonnes but will accommodate loads up to 2000 tonnes. The dock is ballasted until it is level whilst providing a bearing load of 500 tonnes. These loads are then monitored throughout the transfer process with the ballasting being adjusted to maintain a constant bearing load. In addition, the load between one side and the other can be monitored to ensure that the dock’s transverse ballast distribution does not create any longitudinal torsional moments (Note: when free floating, this is ensured by correcting dock heel) Two transfer locations were considered, one for submarine transfers and one for the LHD transfer. As these involved different quayside levels and dock drafts, a removable extension piece was provided in way of the grounding cylinders to enable adjustment to the pontoon deck height relative to the quayside level. This avoided the need to build up the height of the grounding pads thus keeping a clear jetty area. 7.3 Transfer Procedure The general procedure for transfer onto the dock is:

Step 1 – Dock is raised approximately 300mm higher than the required transfer level and manoeuvred into position. The dock is held in position by the mooring lines.

Step 2 – Dock uniformly ballasted until grounding cylinders touch grounding pads. Minor cylinder adjustment, if required, to ensure correct dock level.

Step 3 – The shore end ballast tanks are further ballasted until a load of approximately 500 tonnes is shared between the cylinders. This ensures that the dock is properly grounded and fixed vertically in line with the shore levels







Step 4 - As the vessel is manoeuvred onto the dock, the ballast tanks under the load are deballasted to provide lift equivalent to the ship load to be supported.

Step 5 – As the vessel moves further on, additional ballast tanks are deballasted ensuring that the lift per tank group matches the ship load per tank group along the dock length.

Step 6 – When the vessel is in the undocking position, the shore end ballast tank group is deballasted until grounding reaction is zero.





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Step 7 – Dock raised 300mm clear of grounding pads and manoeuvred to deep sink basin

During the transfer procedure the ballast in the shore end tank is adjusted to maintain the required bearing load ensuring consistency of support. Once the dock has reached the deep sink basin, normal docking evolution procedures apply. 7.5 Dock Depth and Shore Levels The pontoon depth was selected to give the required lift capacity at working draft and for transverse strength. In this case additional needs were: 1. Submarine Transfer: Draft to give 69t/m

lift at minimum tide height 2. LHD transfer: Draft to give 150t/m lift at

minimum tide height 3. Minimum Freeboard of 300mm when at

maximum tide during transfer The sidewall depth was selected to ensure that the minimum freeboard was not less than 2000mm when the dock is at deep sink. This depth was also sufficient to provide adequate longitudinal strength. The depth of water over the pontoon at deep sink is based upon the height of the vessel above the pontoon during shore transfer, the ships docking draft and a clearance between the blocks and keel of not less than 600mm The resulting levels for Dock 1 are shown in figure 6.

8. Structure 8.1 General Arrangement Since dock 1 and dock 2 are required to operate as a single dock, each dock was kept dimensionally the same in transverse section and the same structural configuration used in both. Longitudinally, the length of each tank group was 16.50m with 6 and 8 tank groups used in Dock 1 and 2 respectively.

Figure 6 - Dock 1 Transfer and Water Levels


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The dock structure is steel designed to the Classification Society Rules of Bureau Veritas for Floating Docks. The structure consists of a series of transverse bulkheads evenly distributed over the dock length. The docks’ structure was designed on the basis of operating together with the exception that longitudinal strength was designed on the basis of each individual dock as the rocking joint did not allow longitudinal bending moments to transfer between docks. In the design of the splice plates, the longitudinal strength of the combined docks was investigated by simulating the land transfer of the LHD on to the dock and examining the loadings across the joint between the two docks.

THIS SECTION

SAFETY

DECK

TOP DECK (PLATING REMOVED)

CENTRELINE WT

BULKHEAD

INTERMEDIATE LONGITUDINAL

WT BULKHEAD

TRV WT BULKHEAD

TRV NWT BULKHEAD PONTOON DECK

PLATING REMOVED

Figure 7 - Typical Structural Section of the AMC Floating Dock

8.2 Vessel Loadings The various combinations of ship and dock resulted in the following loadings:

Dock Configuration

Vessel Lift Distributed

Lift Dock Draft

Land Transfer

Dock 1 Max Theoretical 12000t 180 t/m 5.05m No

Dock 1 Submarine 3500t 69 t/m 2.90m Yes

Dock 2 Max Theoretical 16000t 180 t/m 5.05m No

Dock 1 + 2 LHD 18000t 150 t/m 4.50m Yes

Dock 1 + 2 Panamax 28000t 180 t/m 5.05m No

Table 2 - Vessel Loadings


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The keel blocks to support these loadings were designed for a standard spacing of 1650mm whereas the bilge/side blocks were designed for support on the transverses spaced 3300mm apart. The Keel and bilge blocks had a nominal capacity of 350t and 250t each respectively. A pair of longitudinal girders are provided either side of the centreline for the purpose of accommodating the submarine cradle blocks at any position along the dock. 8.3 Hydrostatic Loading The loadings on the tank boundaries depend on the difference between the hydrostatic loads on each side of the tank boundary and occur due to:

a) Differential Ballasting during docking evolutions

b) Differential Ballasting during shore transfer

c) Deballasting of a single tank to permit inspection

The hydrostatic loadings on the hull shell also depend on the difference between the tank level and the dockwater and vary according to the weight, weight distribution and hull form of the ship and the draught of the dock. Figure 8 illustrates hydrostatic loadings on the hull shell. An air cushion is provided in the side tanks to prevent over sinking of the dock. The air cushion is created by trapping air which compresses until equilibrium is reached at maximum deep sink. The depth of the air cushion is controlled by the depth of the air pipe below the safety deck and is set during the deep sink trials. This creates loading on the safety deck when at deep sink. As there are a number of penetrations in the safety deck the effects of loss of air cushion pressure (puncture condition) needs to be taken into account which will create additional loadings on the boundaries of the affected tanks.

9. Dock Manoeuvring The dock was required to be manoeuvred between four locations:

1) Deep Sink Basin – for docking evolutions

2) Shore Transfer Quay – transfer of vessels to and from shore.

3) Ship Repair Berth – for repairing ships on the dock, where existing shoreside cranaege is provided

4) Lay up Berth – for when the dock is not in use.

. A study was carried out to assess the capability of the dock with a docked vessel to be manoeuvred by mooring winches located on the safety deck with wind speeds up to 12.8 m/s. The position of the

Figure 8 Hydrostatic Heads

Figure 9 – Dock 1 Mooring and Manoeuvring


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mooring wire anchor points was constrained by the need to provide accessible positions at the quayside. A computerised control system was provided which monitored the dock position via GPS and the mooring line loads and lengths. Manoeuvring was carried out using a joystick control. At the quayside, the mooring winches are used to hold the dock onto the quayside during shore transfers.

10. Power It was not practical to provide shore feeders permanently connected to the dock to cover the range of locations. In consequence, the dock was provided with a main generator in the starboard sidewall and a standby generator in the port sidewall. Only when the dock is at the lay-up berth or ship repair berth is shore power provided.

11. Main Pumping System The lifting and sinking of the dock is undertaken by the main dewatering system using centrifugal pumps located in the pontoon for deballasting and free flooding for ballasting.

Figure 11 - Layout of dewatering system on Dock 1

The size and quantity of pumps were based upon the need to provide a reasonable shore transfer speed when using only two pumps and the need to provide a reasonable lifting time when operating all four pumps. The resulting pumping capability is shown in Table 3.

AUXILIARY SWITCHBOARD DOCK SERVICES

240 1ph 50Hz

DOCK SERVICES

440v 3ph 50Hz

EMERGENCY

GENERATOR

G

REPAIR STAT IONS 3 OFF (P&S) 415v 3ph 50Hz 240v 1ph 50Hz

MAIN SWITCHBOARD MAIN

GENERATOR

G DOCK SERVICES 240v 1ph 50Hz

DOCK SERVICES

440v 3ph 50Hz

YARD SUBSTATION

415v 3ph 50Hz

SHORE

FEEDERS

FWD

DOCK 1 - PORT SIDEWALL

DOCK 1 - STARBOARD

SIDEWALL

DOCK 2

FEEDER

G

PRIMARY

CROSS DOCK

CABLE

AUXILIARY

CROSS DOCK

CABLE

Figure 10 - Power System Schematic for Dock 1


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Dock Combination

Function Number of

pumps Total Pump Rate Notes

Combined Docks

Normal Docking

Land Transfer

8

2

592 tonnes/min

148 tonnes/min

Lift a 28,000 vessel in 2 hours

LHD (150 t/m) transfer speed 0.06km/hr

Dock 1

Normal Docking 4 296 tonnes/min Lift a 12,000 vessel in 2 hours

Normal Docking 4 296 tonnes/min Lift a 3,500 vessel in 1 hour

Land Transfer 2 148 tonnes/min Submarine (69 t/m) transfer speed 0.13km/hr

Table 3 - Pumping Capability Pumping is normally carried out at a constant rate but there are occasions when slower rates are required such as during the process of suing or when ballast levels are low to avoid suction loss. The slower rates are achieved by ‘throttling’ the valves instead of using variable speed pumps which were considered problematic. For sinking the dock, 4 inlets are required but during shore transfers, the number of Inlets was increased to 8 to provide greater flooding rates under low head conditions. Dock 1 was divided into 12 tanks (See Figure 11) and 16 for Dock 2. Each ballast tank is separated from the dockwater by two valves; a main hull valve and a compartment valve. The main valves (Inlet and Discharge) are of the screw down type gate valve operated by electric motor actuators with handwheel for manual backup. The compartment valves are of the vertical sliding gate type operated via reach rods by an electro-pneumatic press on the safety deck. The valves are failsafe in that loss of electrical or air supplies results in the valve failing shut. In addition, the electro-pneumatic press can be operated locally, and in the event of loss of electrical supply/signal, air pressure can be used to raise the valve. If there is no air pressure, the valve can be raised or lowered using a portable air compressor. The valve control compressed air system is designed to permit the cycling of all valves twice per minute. The system ensures that in the event of power/air failure, the dock would immediately stop in a safe condition without the need to manually close a multitude of valves – a lengthy period during which the dock could develop a dangerous trim, heel, or deflection. The air reservoir capacity allows further limited valve manipulation to bring the dock into a safe condition. The main inlet or discharge valve are kept open throughout the ballasting or deballasting process respectively with control achieved by manipulation of the compartment valves.

Figure 12 - Typical Arrangement of Dewatering System Valves and Pumps


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The dock is provided with a computerised control system capable of automatic, semi-automatic and manual operation. Sensors monitor dock draft, heel, trim, longitudinal and transverse deflection, tank levels, and, when in shore transfer mode, the grounding loads. Since bending moments in the dock structure result in structural deflection, tilt meters are provided at various positions in the dock to monitor the transverse and longitudinal deflections of the pontoon. Using this information, the control system automatically adjusts the ballast levels to reduce bending moments and thus deflections whilst keeping the dock on level floatation throughout a docking evolution or shore transfer.

12. Corrosion To protect against corrosion particular care was taken with the choice and application of the preservative coatings. In addition, the dock is provided with an Impressed Current Cathodic Protection (ICCP) system and the ballast tanks are provided with sacrificial anodes. Environmental Protection

13. Environmental Protection To prevent environmental contamination of the dock water during ship repair activities, e.g. Hydroblasting, the dock is provided with a rainwater collection system where contaminated water from the pontoon deck drains to a collection tank via drains located at the end of the pontoon deck, one each side, and then pumped ashore for processing. An upstand at the end of the pontoon deck prevents runoff from the pontoon deck into the dock water.

14. Construction The build strategy adopted for the dock was based upon the following:

Design was taken to a class-approved status, rather than reliance on a performance specification, in order to fully define the end-product. Detailed engineering only has been undertaken by the builder

A turnkey contract was awarded and, although a major emphasis was placed on local content, the builder had considerable freedom in how this was achieved.

A block construction and assembly method was used to maximize time under-cover.

Strategic Marine won the contract to build Dock1 with the lower portion containing the ballast tanks (see figure 13) and the bulk of the steelwork being built at their shipyard in Vung Tau, Vietnam, and the upper portion containing the majority of the mechanical and electrical outfit constructed in their facilities in Henderson, Western Australia.

Photo 2 Block Construction

Photo 3 Block Assembly on Berth


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Figure 13 - Construction Demarcation The site selected within the yard for assembly of the fabrication blocks had no existing launchways. Therefore, air bags were used to launch the dock. To protect the air bags from any sharp stones, temporary matting was laid over the length of the launch area (See Photo 4).

Photo 4 - Airbags Being Installed for Launch Photo 5 - Refloating Dock in Australia On completion of the launch, the dock was taken by heavy lift ship for dry tow to the AMC-CUF facilities at Henderson, Western Australia. On arrival, the dock was refloated (See Photo 5) and taken into the AMC-CUF where the upper parts of the sidewalls were fitted. On completion, the dock underwent a series of commissioning trials to set up the dock operating parameters and control systems, after which the final commissioning trial involving the docking and shore transfer of the dredger Volvox Anglia (see Photo 6) was successfully undertaken.

Photo 6 SD Volvox Anglia ready for shore transfer


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The construction of the dock took approximately 2½ years. The key dates were:

Award Contract Aug 2007 Cut Steel Vietnam December 2007 Cut Steel Australia January 2008 Launch November 2008 Start harbour trials May 2009 Complete November 2009 Work up period Last quarter 2009 Official Opening February 2010 December 2009: First Docking and shore transfer: Suction Dredger ‘Volvox Anglia’ June 2010: First Collins Class submarine shore transferred - HMAS Farncomb

At the official opening, the floating dock was given the traditional Nyoongar name ‘Yagan’ by the South West Aboriginal Land and Sea Council in consultation with Nyoongar Elders.

Photos 7 & 8 Docking of a Trimaran built by Austals

13. Conclusion The floating dock concept involving the linking of two docks and the ability to transfer vessels ashore demonstrates the great versatility of the floating dock. This versatility enabled the project to proceed with the construction of dock 1 even though the amphibious (LHD) warship programme remained unknown. The dock provides a platform for land transfers and has the future capability for a second dock to be added to create a combined dock capable of accommodating vessels up to panamax size. The dock features several unusual requirements, such as the ability to manoeuvre, offload and maintain trim to very tight tolerances. Whilst none of the solutions to achieve the requirements are new, it is rare to see these within a single platform. The ability to achieve the design intent places a strong focus on the control system, which allows for automatic, semi-automatic and manual control. Whilst using technology that has been used in previous dock designs, it is configured around the specific needs of the dock and an appropriate balance between “tried and tested” and “state-of-the-art” has been found.


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14. Appendices 14.1 Principal Particulars

Dock 1 Dock 2 Combined

Dimension

Length over Pontoon 99.00m 132.00m 232.65m

Width of dock 53.00m 53.00m 53.00m

Width between sidewalls 44.00m 44.00m 44.00m

Clear width of entrance between fenders 41.80m 41.80m 41.80m

Depth of pontoon at centre line 5.50m 5.50m 5.50m

Depth of pontoon at inner sidewall 5.50m 5.50m 5.50m

Length of sidewall 102.30m 132.00m 235.95m

Height of sidewall above pontoon at inner sidewall 13.20m 13.20m 13.20m

Depth of tween deck space 5.95m 5.95m 5.95m

Width of sidewalls 4.50m 4.50m 4.50m

Height of keel blocks (conventional dockings) 2.00m 2.00m 2.00m

Maximum Draft over keel Blocks 9.20m 9.20m 9.20m

Corresponding freeboard of sidewalls 2.00m 2.00m 2.00m

Minimum depth of water required at site 17.70m 17.70m 17.70m

Lifting Capacity

Working Draft 5.05m 5.05m 5.05m

Maximum Lift at Working Draft 12000t 16000t 28000t

Maximum Distributed Load at Working Draft 180 t/m 180 t/m 180 t/m

Transfer Capacity

Maximum Distributed Load at Transfer Draft = 2.90m 69 t/m - -

Maximum Distributed Load at Transfer Draft = 4.50m - - 150 t/m

Dewatering System

Number of Dewatering Pumps 4 4 8

Dewatering Pump Capacity (per pump) 74 t/min 74 t/min 74 t/min


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14.2 General Arrangement

16500

232650

DO

CK

1 -

PO

NT

OO

N L

EN

GT

H =

99000

16500

1650

16500

16500

16500

16500

16500

16500

16500

16500

DO

CK

2 -

PO

NT

OO

N L

EN

GT

H =

132000

AC

CE

SS

GA

NG

WA

Y

GA

NT

RY

16500

3300

16500

16500

16500

DO

UB

LE

BO

LLA

RD

CA

PS

TA

N

RO

PE

HA

TC

H

FA

IRLE

AD

CO

LLIN

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LE

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Page 18

FE

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VR

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ION

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