Specific terms

Various terms are used to describe the size of boats and ships.

• Moving

  This is the weight of the volume of water displaced by the hull, i.e. the submerged part. We define an empty or light displacement (term used to describe a sailing vessel with no load or cargo, or only ballast) and a maximum loaded displacement. Displacement is expressed in tons. When we speak of a vessel's displacement without further specification, we always mean its maximum displacement.

• Deadweight and tonnage

  Deadweight is an indication of the weight of a boat or ship's transport capacity, and thus differs from tonnage, which is a unit of volume. A ship's capacity by weight and capacity by volume are not the same, as many goods have a different cubage to the unit volume of their...