page_title: Displacement (ship)
section_title: Definitions
hierarchical_section_title: Displacement (ship) / Definitions
caption_attribution_description: English: The Arrival of the First Flotilla of Destroyers From America To the Royal Navy, Devonport, September 1940 Two destroyers, HMS Castleton (formerly American Wickes-class destroyer USS Aaron Ward) and HMS Clare (formerly Clemson-class USS Abel P. Upshur), sit moored alongside each other alongside the Devonport Dockyard, September 1940. They still show their US Navy pennant numbers. .Dockyard workers are aboard preparing the ships for service in the Royal Navy.
context_page_description: The displacement or displacement tonnage of a ship is its weight. As the term indicates, it is measured indirectly, using Archimedes' principle, by first calculating the volume of water displaced by the ship, then converting that value into weight. Traditionally, various measurement rules have been in use, giving various measures in long tons. Today, metric tonnes are more commonly used.
  Ship displacement varies by a vessel's degree of load, from its empty weight as designed to its maximum load. Numerous specific terms are used to describe varying levels of load and trim, detailed below.
  Ship displacement should not be confused with measurements of volume or capacity typically used for commercial vessels and measured by tonnage: net tonnage, gross tonnage, and deadweight tonnage.
context_section_description: There are terms for the displacement of a vessel under specified conditions:
caption: USS Aaron Ward (DD-132), a Wickes-class destroyer, and USS Abel P. Upshur (DD-193), a Clemson-class destroyer, berthed alongside each other. USS Abel P. Upshur on the outboard lies lower in the water as it is more heavily loaded and displaces more water.
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