Bulwark on a ship
What is Bulwark on a ship ?
Bulwark on a ship is a nautical term for a ship’s side to be extended above the level of a weather deck.
It is a Vertical Fore-and-aft plating just above the upper edge of the side of the ship surrounding the exposed deck(s).
It is boundary designed on the ship’s side to prevent passengers and crew from falling to sea.
As protection for crew and passengers, bulwarks fitted on weather decks and it is not intended as a major structural function.
In simple sentence,we can say that , a solid wall like structure fitted on the ship’s side above the upper deck to protect crew member falling into the sea.
As we know that it is fitted only to save falling crew and not intended as major structure so, they are of light scantling.The high stresses connected to adjacent structure is avoided.
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Freeing ports are the opening provided on the ship side to allow the free passing of water on the deck to the sea freely.
It is an Opening or hole in the bulwarks at the level of the deck to drain water from the deck.
As we see the figure of Bulwark ,it is open.
Why it is open ?
The opening is called freeing ports.
Freeing ports are cut into bulwarks forming wells on decks so that the water can drain quickly.
Freeing ports area on each side depend on the length of well deck.
The ports’ lower edge must be as close to the deck as possible. It is appropriate to fit bars spaced about 230 mm apart across the port. Where hinge flaps are fitted and these hinges should be non-corrodible.
Structure of the Bulwark on a ship
What is the height of Bulwark ?
The height of Bulwark is at least 1 metre high on the exposed freeboard and the superstructure deck.
However, a reduced height may be allowed if this interferes with the operation of the ship.
Range of height
In open position,the height should be 1 metre high.These are supported by stanchions.
In some ships,these must not be more than 1.2 metres apart for forward 7 percent (%) of the length of the ships otherwise,it not be more than 1.83 metres.
Construction of the Bulwark on a ship
Bulwark should not be welded to the sheer strake to the half length amidship as this is liable to cause the plating to crack.
This can be done by riveting the bulwark to the sheer strake or by using FLOATING BULWARK, which has the advantages that the space/gap between it and the edge of the deck serve as a freeing port.
It is normally founded in a rounded sheer strake.
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