Ship measurements
Ship measurements consist of a multitude of terms and definitions specifically related to ships and measuring or defining their characteristics. Definitions. Beam - A measure of the width of the ship. There are two types: Carlin - similar to a beam, except running in a fore and aft direction. Complement - The full number of people required to operate a ship. Includes officers and crew; does not include passengers. For warships, the number of people assigned to a ship in peacetime may be considerably less than her full complement. Cube - The cargo carrying capacity of a ship, measured in cubic metres  or feet. There are two common types: Displacement - A measurement of the weight or mass of the vessel, at a given draught. (Merchant ships display gross tonnage ; see "tonnage"), deadweight and the number of items it can carry i.e. TEU 20 ft equivalent units. Displacement is expressed in Tonne (metric unit) ship built for USA will be in imperial tons, Warships are shown in displacement tons or tonne. To preserve secrecy, nations sometimes misstate a warship's displacement. Draft or draught (d) or (T) - The vertical distance from the bottom of the keel to the waterline. Used mainly to determine  the minimum water depth for safe passage of a vessel and to calculate the vessels displacement (obtained from ships stability tables) so as to determine the mass of cargo on board. Draft, Air - Air Draft/Draught is the distance from the water line to the highest point on a ship (including antennas) while it is loaded. Air draft is the minimum height a ship needs to pass under, while standard draft is the minimum depth a ship needs float over. Length between perpendiculars - The distance between where the forward part cuts the waterline and the rudder post of the ship . Shaft Horsepower (SHP) - The amount of mechanical power delivered by the engine to a propeller shaft. One horsepower is equivalent to 746 Watts. Tonnage - a number derived from any of several methods to calculate the volume or other number indicative of a ship's cargo carrying capacity.