Adenosine triphosphate.

The energy storage molecule of most living systems.


The condition in which oxygen is present.

Aft, after.

Toward, at, or near the stern.


A species that is not native to an area (see nonindigenous).


Living in the absence of free oxygen.


Without oxygen.


The culture of aquatic organisms.

Arrow worm.

A planktonic carnivorous marine invertebrate of the phylum Chaetognatha.


Behind or from behind the vessel.


See adenosine triphosphate.



Any solid or liquid weight placed in a ship to increase the draft, to change the trim, or to regulate the stability. For the purposes of this study the term ballast includes sediment, which is the debris that comes out of suspension in ballast water and accumulates on horizontal surfaces in ballast tanks.

Ballast tank.

A watertight enclosure that may be used to carry liquid ballast.

Bending moment.

The product of a force acting at a distance from a support or reference point. The vertical bending moment tends to bend the hull in the vertical plane.

Benthic (benthos).

Living on or in the bottom of the ocean.


Intersection of the bottom and the side; may be rounded or angular as in a chine-form hull. The lower parts of holds, tanks, or machinery spaces where bilge water may accumulate.

Bilge and ballast system.

A system of pumps and piping generally located in the holds or lower compartments of the ship. This system is used for pumping overboard accumulations of water in holds and compartments and for filling, emptying, and redistributing water ballast.

Bilge water.

Stagnant water collected in the lower parts of vessels.


The variety of different types of organisms living in a given area.


The living organisms of a region.


Of, relating to, or located at high latitudes.


An organism that damages the structural integrity of wood or other materials by boring holes into it.


The forward end of a vessel.

Brake horse power (Bhp).

The power produced by the prime mover before entering any reduction gear, if installed.


 The definitions of shipping terms draw extensively on H. Benford. 1991. Naval Architecture for Non-Naval Architects. Jersey City, New Jersey: The Society of Naval Architects and Marine Engineers.

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