Terms & Definitions on Ship Construction

 

Strakes:

        The external hull of the ship consists of a bottom shell, side shell and decks which are formed by longitudinal stripes of plating known as strakes.
 

Garbode strake:

        The strake adjacent to the keel on each side of the ship is known as the Garbode strake and it is of the same thickness as the bottom shell plating.

 

Sheer Strake:

        The uppermost line of plating in the side shell is known as the sheer strake which is 10% to 20 % thicker than the remaining side shell plating.

 

Bilge Keel:

        It is a piece of bulb plate fitted normal to the vessel's shell plating surface along the line of the bilge diagonal and designed to dampen out rolling motions.

 


Bollard:

        It is a single cast steel post securely fastened to the ship's deck to act as a securing point for the mooring lines.

 


Bulwarks:

  • Bulwarks are fitted on the weather decks, which are provided as protection for personnel and are not indented as a major structural feature.
  • It should be at least 1m high on the exposed freeboard and superstructure decks, but a reduced height may be permitted if this interferes with the working of the ship.


Freeing Ports:

        Freeing ports is fairly opening through bulwarks fitted with protection bars or a self-closing lid to allow seawater to run overboard.

 

Centre Grider:

        A primary structural vertical plate fitted on the centreline immediately above the keel plate in a vessel.

 

Cofferdam:

        A Void space between the two bulkheads or decks designed in order to safeguard against intermixing of liquids between two adjacent compartments due to leakage.

 

Coffin Plate:

  • They are used to connect stern frames to the flat plate keel.
  • The stern frame is extended forward far enough to provide a good connection with a flat plate keel.

Duct Keel:

        An internal passage of watertight construction running the same distance along the length of the ship, often from the forepeak to the forward machinery space bulkhead.

 

Stringer Plate:

        The outboard deck strake is known as the stringer plate and the weather deck is usually thicker than the remaining deck plating   

 

Bulbous Bow:

        A bulb-shaped underwater bow which is designed to reduce wave-making resistance and any pitching motion of the ship.

 


Devils Claw:

        A stretching screw with two heavy hooks or claws which is used to secure anchor in the hawse pipe.  

 

Hawse Pipe:

        A cast steel tube running through the forecastle to the vessel's forward through which the anchor chain is rove.

 

Spurling Pipe:

        A tube fitted under the forecastle deck to carry the anchor chain from under the windlass to the top of the chain locker.

 

Margin Plate:

        The outermost strake of the inner bottom or tank top and when turned down to bilge the plate forms the outer boundary of the double bottom tank.

 

Chain Locker:

        A compartment usually positioned forward of the collision bulkhead and is used to accommodate the volume of chain cable attached to each ship.

 

Breast hooks:

        The stem plate is supported at an interval of about 1.5 m by horizontal plates known as Breast hooks, which extend from the stem to the adjacent transverse frame.

 

Cable Stopper:

        The cable stopper is a casting with a hinges lever, which may be used to lock the cable in any desired position and thus relieve the lord of the cable from the windlass either when an anchor is out or when it is stowed.

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 Reference:     Ship Construction By D.J, Eyres

                        Ship Construction for Marine Students By E.A.Stokoe

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