Glossary of Ship Construction Terms

CSL Technical Bulletin 1/CD/tw/V1.01 1 30/11/09

Technical Bulletin 1 March 2009

Glossary of Ship Construction Terms This is a collection of terms which may be useful to have to hand when reading a surveyor’s report relating to hull damage, it is by no means an exhaustive list but has been kept to the basics so as not to become too in depth. Hopefully it will be of some use to the reader.

After perpendicular An imaginary line drawn perpendicularly through the waterline at the edge of the rudder post where it meets the summer load line. Aft Peak bulkhead The first main transverse watertight bulkhead forward of the stern. The aft peak tank is the watertight compartment between this bulkhead and the stern. Ballast Tanks Tanks which are filled with sea water to alter the trim or draught of a vessel Bilge keel A length of offset bulb plate attached at the bilge position along about a third of the length of a vessel to help reduce rolling. The bilge being the area where the side plating meets the shell plating “the rounding of the bilge”. Bow The forward most part of the ship, sometimes termed the “pointy end”. Bulwark The plating that stands vertically above the vessel’s exposed decks,

these are fitted for safety of personnel and prevent loss of items which may come loose during transit, they are not structural members, and if of solid construction must have freeing ports capable of removing wash from the deck area.

Bulbous Bow Fitted to disrupt bow wave generation and reduce the ship’s resistance. Collision bulkhead The foremost transverse main transverse watertight bulkhead. Coaming The surrounding vertical structure around cargo hatches or skylights. Cofferdam Empty space between two bulkheads, often in place to prevent

contamination from one tank to another, in the instance of having a fuel tank next to a ballast tank, the cofferdam would prevent contamination in the event of the bulkhead failing in on tank.

Bulwark Hatch “Coaming”

Freeboard deck Freeing Port



Deep tank Tank extending from the shell plating, or inner bottom to the lowest deck

or higher. Double Bottom The inner bottom is the top of the double bottom structure, below the

inner bottom are stiffeners which attach between the shell plating and the inner bottom plating, the plating plus stiffeners is the double bottom structure. The purpose of the double bottom is to maintain watertight integrity should the shell plating become pierced, it is normal on many vessels for the double bottoms to be used as ballast tanks.

Duct Keel Sometimes know as the pipe duct, it contains piping and valves which

would otherwise have to run through cargo holds, it runs along the length of the vessel from the forward transverse bulkhead of the machinery space. As the name “keel” suggests it runs along the bottom of the vessel’s structure.

Fairlead A reinforced fitting for changing or preserving the direction of a rope, used

mainly in mooring the ship. Floor Transverse member fitted to the bottom structure. Forecastle The raised short superstructure situated above the bow. Forward perpendicular An imaginary line drawn perpendicularly through the waterline where the

forward edge of the stem meets the summer load line. Freeboard Deck The uppermost continuous deck exposed to the weather and sea. Girder A primary structural member. Gusset Triangular plate fitted to distribute forces between two structural members. Intercostal Non continuous section. Keel The backbone of the ship, usually a flat plate running longitudinally, which is

stiffened by a vertical plate being welded to its centreline inside the hull. Midship section This is a cross section taken at the mid position between the two

perpendiculars. Panting The in and out movement of a ship’s plating caused by changes in pressure

due to wave and vessel movement. Rudder The aerofoil fin used for steering the vessel, they come in various forms,

balanced, semi-balanced and unbalanced. Rudder Pintle The pin on which certain types of rudder swing.

Stem

Bulbous Bow

Forecastle



Scantlings Details and dimension of structural members of the vessel. Scupper An outlet for removing unwanted water from the ship’s decks. Sheer strake The uppermost strake of plating of the ship’s side plating Spectacle frame Strength member which shell plating is attached to, the structure projects

out from the vessel to support propeller shafts in twin screw ships. Stem This is the plating or bar where the termination of shell and side plating at

the forward end occurs. Stern The after most part of the ship, sometimes termed the “blunt end”. Stern frame Strength member including the rudder post used in the construction of single

and triple screw vessels.

Stiffener Added for strengthening plating, in the form of a secondary structural

member, flat bar or section.

Superstructure Any structure above the freeboard deck spanning more than 92% the

breadth of the ship Transverse A member running 90 degrees to the centreline of the ship. Tripping Bracket A plate added to the free edge of structural members for reinforcement Tween Decks An abbreviation of between decks. The deck space between two adjacent

decks in a cargo hold. Void An enclosed empty space.

Stern Frame

Rudder Pintles

Semi-balanced rudder

Stiffeners



Wash Bulkhead A partial bulkhead fitted along the centreline in a tank, usually found in deep

tanks and peak tanks to withstand the flow of liquid caused by the ship’s motion.

Watertight bulkhead A transverse bulkhead for separating the ship’s hull into watertight

compartments

Winch A piece of equipment used for winding in ropes, use in mooring operation,

found at the fore and aft ends of the ship. Windlass A similar piece of equipment to the winch used for raising the ship’s anchor,

often combined to operate as a windlass and winch with a clutch to disconnect the windlass

Mooring winches and windlasses on the forecastle deck

Fairlead

Glossary of Ship Construction Terms

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