X-class submarine

Class overview
NameX class
Operators Royal Navy
Preceded byV class
Succeeded byXE class
SubclassesX3, X4, X5-10, X20-25, XT
Completed20
Lost7 (5 scuttled, 1 foundered, 1 collision)
Preserved1
General characteristics (X class)
Typemidget submarine
Displacement
  • 27 tons surfaced
  • 30 tons submerged
Length51.25 ft (15.62 m)
Beam5.75 ft (1.75 m)
Draught5.3 ft (1.60 m)
Propulsion
  • Single shaft; 1 × Gardner 4LK[1] 4-cyl diesel engine, 42 hp (31.3 kW) at 1,800 rpm
  • 1 × Keith Blackman electric motor, 30 hp (22.3 kW) at 1,650 rpm
Speed
  • 6.5 knots (12.0 km/h) surfaced
  • 5.5 knots (10.2 km/h) submerged
Range
  • 500 nmi (926 km) surfaced
  • 82 nmi (151.8 km) @2 knots (2 mph; 4 km/h) submerged
Test depth300 ft (91.5 m)
Complement4
Armament2 × 4,400 lb detachable amatol charges

The X class was a World War II midget submarine class built for the Royal Navy during 1943–44. It was substantially larger than the original Chariot manned torpedo.

Known individually as X-Craft, the vessels were designed to be towed to their intended area of operations by a full-size "mother" submarine – usually one of the T class or S class – with a passage crew on board, the operational crew being transferred from the towing submarine to the X-Craft by dinghy when the operational area was reached, and the passage crew returning with the dinghy to the towing submarine. Once the attack was over, the X-Craft would rendezvous with the towing submarine and then be towed home.

Range was limited primarily by the endurance and determination of their crews, but was thought to be up to 14 days in the craft or 1,000 nmi (1,900 km), after suitable training. Actual range of the X-Craft itself was 600 nmi (1,100 km) surfaced and 80 nmi (150 km) at 2 knots (3.7 km/h) submerged.[2]

  1. ^ "Engine Forum" (PDF). gardnerengineforum.co.uk. Retrieved 10 September 2023.
  2. ^ "How the Royal Navy's X-Class Midget Subs Helped Make D-Day Possible". 6 June 2015.