Marine Measurements Used on This Website


Until recently vessels in Canada were measured in imperial measure (feet & inches). In the database vessels prior to 2000 are so noted. Some vessels show measurements in both the imperial and metric systems. Vessels built after 2000 will record mesurements in metric measurement.

Length Overall: (l.o.a.) Is the measurement of the full extent of the vessel from the tip of the bow to the tip of the stern.

Length Waterline: (l.w.l.) Is the length of the vessel measured at the waterline.

Length Between Perpendiculars: (l.b.p.) Is the length of the vessel measured between the rudder post and the hull at the bow waterline.

Breadth: Is the measurement of the full extent of the width of the vessel at its widest post

Depth: Is the amount of the depth of water the vessel draws when afloat.


Tonnage can be expressed in a number of different terms. If tons are used then this refers to cubic capacity of the vessel. If tonnes are used it refers to the weight of the vessel measured in metric tonnes.

Gross Registered Tonnage (gt.): the total of the permanently enclosed space above and below decks (exclusive of the wheelhouse, the chart room, the radio room, the galley and other operational spaces above deck.)

Net Registered Tonnage (nt.): this is a measurement of the earning space in a vessel without spaces such as the machinery space, the accomodation of the crew, working spaces and ballast tanks.

Deadweight (dwt.): this is the difference between the light displacement and the load displacement giving the wight in metric tonnes o the passengers, crew, supplies, ballast and cargo. The light displacement is the weight of the ship's hull, engines, and equipment used in operating the vessel. The load displacement includes the weight with everything on board (crew, equipment and cargo).

Load marks (also known as tonnage mark , Plimsoll mark or International Convention Loadline) is painted on the side of the vessel. The different loading marks show the allowable level that the vessl may be loaded to in different environments such as freshwater and seawater in different seasons.

To quote from this article please cite:

MacFarlane, John M. (2012) Marine Measurements Used on This Website. 2012.

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