ABS American Bureau of Shipping; a vessel classification agency which also assigns international loadlines.

admeasure - to measure, calculate, and certify, for the purpose of registration, certain dimensions of a vessel as well as its gross and net tons.

affreightment - a contract for the movement of cargo, in which the cargo owner/shipper is neither charterer nor operator of the vessel.

AHP Above Head of Passes; used with mileage designations on the Mississippi River, the Head of Passes being mile zero.

AIWW Atlantic Intracoastal Waterway.

anchor billboard - a structure on the deck of a vessel upon which the anchor is mounted when not in use.

anodes metallic plates which, when attached to the hull of a vessel, decompose due to electrolysis, reducing deterioration of the hull plate.

athwartship - transverse or across a vessel from side to side.

autoignition temperature - the minimum temperature required to ignite gas or vapor without a spark or flame being present. Values given are only approximate and may change substantially with changes in geometry, gas, or vapor concentrations, presence of catalysts, or other factors.

ballast any substance, other than cargo, which is usually placed in the inner compartment of a vessel to produce a desired draft or trim.

bareboat charter - (demise charter) a form of vessel rental in which the charterer assumes total responsibility for the vessel and its operations as if it was their own.

beam the breadth of a vessel.

bell suction - the flared open end of a cargo pipeline which is situated at close tolerances to the bottom of a liquid cargo tank.

bilge the lower inner space of a vessel's hull.

bin a walled enclosure built on the deck of a barge for the purpose of retaining cargo; also called a pen or cargo box.

bitt (bollard or timberhead) a single or double post on a vessel or wharf to which lines are tied.

boiling point - the temperature at which the liquid boils, given in °C and °F at a pressure of 760 min Hg, one atmosphere or 14.7 psia. Thus, the boiling point is the temperature at which the vapor pressure is 760 mm Hg, one atmosphere or 14.7 psia.

bollard pull - the static pulling force of a tugboat measured in pounds.

bounding angle - a steel angle used for reinforcement at the junction of two steel plates.

bow the forward or front end of a vessel.

boxed end - the end of a barge which is squared for the fun depth and width of the hull.

bridle a V-shaped chain, wire, or rope attached to a vessel being towed to which the towline is connected.

buck frame - a transverse truss.

bulkhead an upright partition separating compartments.