X-class submarine

X24 on display at the Royal Navy Submarine Museum, Gosport, Hampshire
Class overview
Name	X class
Operators	Royal Navy
Preceded by	V class
Succeeded by	XE class
Subclasses	X3, X4, X5-10, X20-25, XT
Completed	20
Lost	7 (5 scuttled, 1 foundered, 1 collision)
Preserved	1
General characteristics (X class)
Type	midget submarine
Displacement	27 tons surfaced 30 tons submerged
Length	51.25 ft (15.62 m)
Beam	5.75 ft (1.75 m)
Draught	5.3 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 depth	300 ft (91.5 m)
Complement	4
Armament	2 × 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]