Prior entry into the dock, the shipyard would need to make the necessary keel block arrangements to prepare for the ship's arrival. When the ship is on route to the dock, communications between the ship's Officer and the Dock Manager should be established so that the required draughts and trim can be adjusted on the ship as for normal dock entry. In the case when the ships is entering the dock in a damaged state, the required draughts and trim may not be attainable. This case would require the ship to be docked in a floating dock (which will not be explained here).
There are various duties and logs that need to be taken before and when the ship is entering the dock. These are summarized in the topics descussed below:
Turn stabilisers into their stowed position
Withdraw any engine room bottom speed logs into the stow position
Lower any cranes or derricks to the stowed sea-going position
Place all hatch covers and athwartships beams into position to ensure continuity of strength throughout the length of the vessel
Complete any ballast operations to satisfy the docking requirements regarding list and trim
Reduce any free surface activity within tank levels where possible
Brief the ships Chief Officer of the need to obtain 'wet soundings' as well as 'on the block' 'dry soundings'
Sound round all internal tank soundings (wet soundings) before entering the dry dock
Communicate with the Dry Dock Manager regarding the vessels' draught and trim to suit the dock construction
Prepare all necessary documenation which may be required to complete the docking operation and the expected workload inside the dock
Calculate that the ship has adequate positive stability to withstand the expected 'P' force that will affect the vessel when taking the keel blocks. The GM should be large enough to compensate for a virtual rise in 'G' once the keel touches the blocks and the vessel enters the critical period
To enhance the positive stability all slack tanks, and subsequent free surface effects should either 'pressed up' or alternatively pumped out if possible
Any repair list should be completed and kept readily avialable to hand over to the dock authorities
All utilities required should be ordered in ample time to be supplied to the ship on docking
All store rooms, toilets and ships cmopartments should be locked for the purpose of security and any loose gear should be stowed away before entering the dock
Rig fenders around the vessel before entry into the dock
Plug and secure all upper deck scuppers to reduce the risk of pollution
-Tugs engaged at rendezvous position
When it is decided that a ship is to enter the dry dock the first thing that is done is the keel block arrangement. This is done by the Asst Dock Manager. The centre keel block arrangement is always the same. However, the rest of the keel blocks are arranged according to the ships' structure. These are based on the ships construction drawings.
Docking of any ship depends on the ship's draught. It is important to note the draught of the ship so as to estimate the tide at which she should enter the dock. The draughts of container ships are usually 5-7m and for tankers about 3m.
When the ship is near the entrance of the dock, a crane is used to lift wires to secure the whip to the dock winches. Two winches are secured at the aft end and two at the forward end of the ship. These winches are used to guide the ship into the dock and bring it to the exact spot at which it should be laid on the keel blocks. A ship entering a dry dock is shown in the picture below:
Once the ship is braught directly above the keel blocks on which it will be laid on, divers are sent in the dock to ensure the ship sits exactly on the keel blocks as the water is being pumped out of the dock.
The pump room located at the foward end of the dock controls the rate of water being pumped out of the dock. This process can also be refered to as de-ballasting the dock. This is what a ship will look like after the dock is fully de-ballasted.
Once the ship sits properly on the keel blocks, fire hydrants, safety signs and a shore gangway is attached to it. Safety personnel then inspect the ship and mark dangerous areas on it with a Red tape. This is done so that hot work can be carried out with care. An example of such an area would be the fuel oil tanks.
Application for all the necessary permits are then made. These permits include hot work permit, cold work and enclosed space permits. Gas checks are also carried out in enclosed spaces every day to ensure maximum safety.
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