Stickleback-class submarine

The Stickleback-class submarines were midget submarines of the British Royal Navy initially ordered as improved versions of the older XE-class submarines. They were designed to allow British defences to practice defending against midget submarines since it was theorised that the Soviet Union had or could develop such craft.^[1]

X51 Stickleback at Imperial War Museum Duxford
History
United Kingdom
Name	Stickleback class
General characteristics
Type	Midget submarine
Displacement	35.2 tons surfaced 39.27 tons submerged
Length	50 ft 8 in (15.44 m) (pp) 53 ft 10 in (16.41 m) (oa)
Beam	6 ft (1.8 m)
Draught	7 ft 6 in (2.29 m)
Propulsion	1 shaft diesel electric, 1 Perkins P6 6 cyl diesel, 1 electric motor, 50 bhp/44 shp
Speed	6.5 knots (12.0 km/h; 7.5 mph) surfaced 6 knots (11 km/h; 6.9 mph) submerged
Complement	5
Armament	2 detachable 2-ton side charges

The Royal Navy developed plans to use these craft to carry a 15-kiloton nuclear naval mine (based on the Red Beard weapon) codenamed Cudgel into Soviet harbours.^[1] The project was unsuccessful as there were problems finding and paying for the necessary fissile material.^[2]

Boats

There were four boats, launched 1954–1955:^[2]

• X51 Stickleback, launched 1 October 1954, sold to the Royal Swedish Navy in 1958 and was renamed Spiggen (Swedish name for "Stickleback"). After a period on display at the Imperial War Museum Duxford, and then in storage at Portsmouth Naval Dockyard, X51 was moved to the Scottish Submarine Centre^[3] in Helensburgh, where it has been on display since 2018.^[4]
• X52 Shrimp, launched October 1954, scrapped 1965
• X53 Sprat, launched 30 December 1954, loaned to US Navy 1958, scrapped 1966
• X54 Minnow, launched 5 May 1955, scrapped 1966