14 Completing the Ship

8/12/2019 14 Completing the Ship

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14 COMPLETING THE SHIP

14.1 AIMS OF THE LECTURE

a) To outline the remaining tasks following the construction works of the ship

b) To examine various methods of launching ships

c) To explore the procedures of handing over the ship to the owner and yards remaining

responsibilities

14.2 TASKS BEFORE HANDLING OVER THE COMPLETE SHIP

When the construction work has been completed and most of the blocks have been joined the

ship is ready to undergo further completing stages as follows:

a)

Launching

Following the joining process on the building berth or building dock, and on-berth outfitting

works the ship is ready to be launched or floated out dependent on the system being

implemented, if the blocks were joined on the building berth more likely the ship will be

launched, and if the block were joined on the building dock the ship definitely will be floated

out, the decision of launching method is usually determined by the availability of the

facilities, and the size of the ship.

b) On-board outfitting

After the ship has been launched or floated out, it is usually dragged to the outfitting quay for

further completion of the remaining tasks. One of these tasks is outfitting, which is known as

on-board outfitting.

c)Trials

When a ship is completed, various trials have to be carried out in order to confirm that theship's performance meets the specifications required by the ship owner when the

Memorandum of Agreement was signed. These trials are also known as Acceptance Trials.

d)

Ship delivery

Upon the acceptance of ship trials results by every party concerned the shipyard can now

prepare for the delivery of the ship to the owner. The preparation works are mostly in the

form of documents and administration work, such as certificates of compliance from various

parties, certificates of guarantee and operation manuals from engine and equipment

manufacturers, ship calculations and drawings.


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14.3 METHODS OF LAUNCHING

Traditionally ships were built on building berths using sequential method i.e. framing, hull

plating, machinery, and outfitting, but since the introduction of block system and with the

increasing in the size of ships to be built, for safety reason and for practical alignment of the

blocks there are more and more shipyards in favour of having their ships built on the building

docks.

After the block joining has been completed the ship is ready to be launched. There are

various methods of ship launching dependent on the size of the ship, and the availability of

the launching facility. Ship launching can be categorised into two main methods i.e.

launching and floating out, and each of these categories can be divided into more specific

methods as follows:

a) Longitudinal launching

b)

Side launching

c) Use of graving dock

d) Use of floating dock

e) Use of ship lifting

14.4 SHIP LAUNCHING

Ship launching is mostly applied for smaller ships due to a number of risks conceive in it.

Slipway is used for launching the ship; the slipway occasionally is partially or wholly belowhigh water level and is kept dry by doors, which will be opened when the construction is

ready to provide some buoyancy to the ships hull. More often the ship is wholly constructed

above the water and then slid into the water when it is ready. For small ships a cradle is

sometimes used for launching, which will be lowered down on wheels. For larger ships

greased ways under the action of gravity is required for sliding the ships. There are several

ways of launching the ship among other things would include:

a)Longitudinal launching

Longitudinal launching is the most widely and oldest method being used for launching ship,usually the ship slides stern first due to various reasons such as: ships stern is more buoyant

compared to its bow, there are more delicate parts of the ship at its tern such as: propeller,

rudder, propeller shaft that need precision alignment and might be damaged due to high

reaction force from the slipway when the whole ships hull nearly floats, but there are some

bow first launches can also be found.


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In stern first launch slid ways are prepared around the ships bottom with certain degree of

inclination, and sometime are cambered too, the gaps between them and the fixed ground

ways are filled with grease, so that the weight of the ship can be transferred. When the

triggers are pulled away the ship will slid under its gravity down its inclined ways,

buoyancy will build up upon it enters the water until it reaches sufficient value to pivot the

ship at its fore poppet and continue sliding until floated freely on the water, and then

dragged slowly to stop the ship from launching too far that might hit other objects at the

other end of the water front.

Following are some illustration of ship end launching:

Figure 14.2 Illustration of Longitudinal launching

Figure 14. 1. Longitudinal launching


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Figure 14.3. Floating process illustrasion during end launching

Figure 14.5. Ship dragging

Figure 14.4 Launch trigger


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There are some hazards to be considered during end launching process, which include:

The grease applied might be too much or too little, which will affect the slippery

of the slid ways,

The grease might be squeezed out from the slid ways and gives no effect to the

slid ways,

The ship might slid to the wrong way instead of stern way and plunge due to

uneven sliding velocity, or side wind launching is taking place,

The ship might be unstable upon it floats onto the water and capsize,

The fore structure of the ship might not strong enough and damaged due to

pivoting force from the poppet,

The dragging applied to the ship might not sufficient (too much or too little)

In order to overcome the hazards launching calculation should be carried out to investigate

every possibility that might happen during ship launching, and the safety precautionscould be taken. Based on the launching calculation launching curves can then be drawn to

predict the behaviour of the ship during its launching along the distance of its travel tracks,

these include:

Weight of the ship,

Buoyancy builds up,

Moment of weight about fore poppet,

Moment of buoyancy about fore poppet,

Moment of weight about after end of ground ways,

Moment of buoyancy about after end of ground ways

Figure 14.6. End launching curves


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b)Side launching

There are two main reasons for undertaking side launching i.e. the ship is considerably small

and the water front space is limited. There are three methods of side launching:

The ship slids down on slidways built well down under the water, The ship slids down the end of the slidways and then tips or drops off into the

water,

The ship is built on piles which are made to collapse by slidways push and make

the ship to fall into the water.

The hazards in side launching are great, because the ship slids into the water with a violent

moves and roll heavily, therefore the ships stability at high degree and water tightness are to

be considered well. To prevent any unexpected things that might ruin the side launching due

to low stability effects and heavy rolling the ships super structure will not be joined on untilthe hull is launched. The hazards in conjunction with side launching would include:

The heeling angle of the ship might be to high that could cause the ship capsize

When the ship tips into the water the righting moment might not be able to make

the ship roll back into the right position

The collapsed piles might damage the ships hull when float up from the water

Figure 14. 7. Side launching methods

Figure 14. 8. Side launching


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c)Air bag ship launching

Air bag ship launching was i

break through to the traditio

small to middle size ships. Th

cord- reinforced rubber layer

into the tube which make it a

then the ship is pushed with

rubber of the air bags the ship

Beside for launching new sh

maintenance, and for salvage.

Fig

troduced by Evergreen China. The innovat

al slide-board technology which commonly

e basic body of the cylindrical air bag is ma

with hemispherical heads at the both ends

le to roll. The air bags are inserted under t

relatively small force, due to its friction wit

rolls down into the water.

ip air bag can also be used for rolling up

re 14.9 Air bag ship launching

Figure 14. 10 Air bag

ion has contributed

used in launching

e from synthetic

, air is compressed

e ship bottom, and

h the outer surface

ships intended for


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14.5 FLOATING OUT

Instead of being launched it is much safer and simpler particularly for large ships to be

floated on the graving dock, floating dock or ship lift. Other advantage of these ship floating

facilities is they can also be used for maintenance and repair of ship with regard to the ships

under water structure. The only disadvantage is their investment cost is relatively high

because of the equipment needed to support them. In building a new ship the whole structure

of the ship can be completed prior of its floating out, without being troubled by the high of

center of gravity caused by superstructure, because the ship will not roll when it is floated

out.

a)Graving dock

Graving dock is a box like pool dig on land under the water level equipped with gate, which

can be opened using hydraulic device. When the dock has been filled with water the ship is

then pull out by tug boats. Large pumps are usually utilised to fill in and to empty the dock.

Conventional docks were built followed the shape of ships so that supports could be attached

easily and people who worked on it would have easy access as well, but since shipbuilding

was not considered an art anymore, and the shape of merchant ships are becoming more like

giant box, thus the shape of graving docks are also more like box with rectangular profile.

Since massive weight will be loaded to the dock floor, comprehensive calculation has to be

undertaken in designing the docks structure. The mechanism of the gate has also to be

designed well with consideration on the hydrostatic forces applied on it and the access for its

movement including the hydraulic system that are usually being used for opening and closingthe dock gate.

Figure 14.11 Graving dock


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b)Floating dock

Floating docks are mostly used for maintenance and repair but occasionally they are also used

for constructing new ships, this is mainly due to calmness consideration particularly with

regard to the alignment tasks. Floating dock is actually a pontoon that can be submersed and

floated for floating and lifting ships. Instead of pumping water in to and out from the dock

such as in the case of graving dock, in floating dock the water is pumped into or pumped out

from the ballast tanks, and therefore floating dock does not need any gate to keep the dock

dry, the pump rooms are usually located in the dock walls.

Figure 14.12 Conventional graving dock

Figure 14.13 Floating dock


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c)Shiplift

Shiplift is made up of structural platform that can be lifted up and lowered down vertically by

utilising synchronised hydraulic or mechanical hoists, other name for shiplift is Mechanical

Lift Dock. The main purpose of shiplift is to lift up and lower down ships, and the works

that to be done in relation to the ship are conducted inland, therefore for transferring the ship

to and from the shiplift connecting rails and transfer cradles are provided.

The ship to be floated is transferred from the construction shop/plant inland on cradles to the

platform on the shiplift, then the platform is lowered down until the ship floats and can be

towed out by tug boats. The opposite procedure is carried out to bring a ship to the

maintenance shop.

The advantages of shiplifting compared to ship launching or dry docking are:

- Shiplift can serve theoretically almost unlimited number of ships, while slipwayor dry dock can only serve one ship at the time, because the ships are constructed

not on the shiplift but inland and then transferred to the shiplift.

- The time needed to float or to lower the ship relatively faster compared to

launching as well as dry docking.

Figure 14.14 Shiplift


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14.6 SHIP TRIALS

Trials and inspections are conducted by the Board of Inspection and Survey on all ships prior

to final acceptance for operation, to determine whether or not the contract and

authorized changes there to have been satisfactorily fulfilled. The builders trials and

acceptance trials are usually conducted before a new ship is placed in commission. After

commissioning, a final contract trial is held.

In general ship trials can be categorised into two activities i.e. basin trials and sea trials. Basin

trials are conducted prior to sea trials on the quay as a means for ensuring the shipyard that all

the equipment and machinery performance in accordance to the specifications, and as

preparation before conducting official sea trials. Besides concerning people from the shipyard

Figure 14.15 Shiplifting yard

Figure 14. 16 Transfer cradle


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other patties representatives are also usually invited as witnesses to the basin trials. Items to

be inspected during basin trials among other things are:

Propulsion systems,

Manoeuvring systems,

Static stability,

Electrical and electronic systems,

Auxiliary engines,

Navigation and communication systems,

Safety and fire fighting equipment,

Air conditioning and ventilation systems.

When satisfactory results have been obtained from the basin trials shipyard can proceed for

the sea trials. Sea trials may be carried out several times according to their purposes, and

mostly the same trial items are repeated these include:

Builders trials.

Acceptance trials.

Final contract trials.

Standardization trials.

Tactical trials (for military ships).

Full power trials.

Economy trials.

The main aims of the sea trials are to gather information of the ships performance with

regard to its operation that being the concern of the ships owner. Trial items to be conducted

during sea trials among other things are:

Speed,

Manoeuvrability,

Engine performance,

Fuel consumption,

Ships vibration and noise,

Anchoring system,

Navigation and communication systems,

Safety equipment,

Data obtained from every item of the trials should be recorded and included in the ship trials

report for further follow up by the concerning parties, either the ships performance is

accepted or some changes and adjustments should be undertaken.


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Figure 14. 17 Engine trial

Figure 14. 18 Life saving trial


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Figure 14. 19 Speed trial

Figure 14. 20 Manoeuver trial


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14.7 SHIP DELIVERY

Beside administration works shipyard also has to list and store spare parts that have to be

carried on board the ship, which is usually described in the attachment of the contract.

It is a common practice that during the ship commissioning the owner sends its crews to the

shipyard for familiarisation with the ship and its system; it can take for several days or weeks

dependent on the size and sophistication of the ship.

Sometimes the ship is built not in the same country as the owner or port of register, and even

the distance is relatively far, therefore it should be stated in the contract who is responsible to

deliver the ship to the designated location, because there is cost involved in it.

To deliver the ship it is not unusual that a third party is hired. This third party is usually a

firm that specialised for delivering ship. It provides crew, bunker, and all requirementsdemanded for the journey.

There is a warranty period usually given by the shipyard to the ship owner for duration

between three months to one year for the ships construction, machinery, and equipment that

are not functioning well or damage not due to operators fault. For this purpose there is

usually a certain percentage of payment is detained by the ship owner until the warranty

period is due.


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14.8 CONCLUDING REMARKS

a) Tasks to be completed before handling over the ship include: launching, on-board

outfitting, trials, and ship delivery.

b) There are five methods of ship launching:

Longitudinal launching

Side launching

Use of graving dock

Use of floating dock

Use of ship lifting

c)Ship trials are conducted prior to final acceptance for operation, to determine whether or

not the contract and authorized changes there to have been satisfactorily fulfilled.

d)In general ship trials can be categorised into basin trials and sea trials.

e)When every thing has been completed the ship is then delivered to the owner for

operation.

14 Completing the Ship

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