HMS Excalibur

HMS Excalibur (S40)
History
United Kingdom
NameExcalibur
Ordered26 August 1947
BuilderVickers Armstrong
Launched25 February 1955
Completed22 February 1958
IdentificationPennant number: S40
Nickname(s)The Excruciator
FateScrapped, 1968
NotesBuilt at a cost of £1,142,000
General characteristics
Class & typeExplorer-class submarine
Displacement
  • 780 long tons (790 t) (surfaced)
  • 1,000 long tons (1,000 t) (submerged)
Length178 ft (54 m)
Beam15 ft 8 in (4.78 m)
Draught11 ft (3.4 m)
Propulsion
Speed25 knots (46 km/h; 29 mph) (submerged)
Complement41
ArmamentNone

HMS Excalibur was an Explorer-class submarine, the sister ship of HMS Explorer, the two submarines being the only high-test peroxide (HTP) powered submarines to be constructed for the Royal Navy. She is the only commissioned ship in the Royal Navy to be named as such, in honour of the sword of Arthurian legend. In 2025, the Royal Navy christened a non-commissioned uncrewed submarine of the same name into service for the purpose of testing unmanned underwater systems.