HMS C21

History
United Kingdom
Name	HMS C21
Builder	Vickers, Barrow
Laid down	4 February 1908
Launched	26 September 1908
Commissioned	18 May 1909
Fate	Sold, 5 December 1921
General characteristics
Class and type	C-class submarine
Displacement	290 long tons (290 t) surfaced 320 long tons (330 t) submerged
Length	142 ft 3 in (43.4 m)
Beam	13 ft 7 in (4.1 m)
Draught	11 ft 6 in (3.5 m)
Installed power	600 bhp (450 kW) petrol 300 hp (220 kW) electric
Propulsion	1 × 16-cylinder Vickers petrol engine 1 × electric motor
Speed	13 kn (24 km/h; 15 mph) surfaced 8 kn (15 km/h; 9.2 mph) submerged
Range	910 nmi (1,690 km; 1,050 mi) at 12 kn (22 km/h; 14 mph) on the surface
Test depth	100 feet (30.5 m)
Complement	2 officers and 14 ratings
Armament	2 × 18 in (450 mm) bow torpedo tubes

HMS C21 was one of 38 C-class submarines built for the Royal Navy in the first decade of the 20th century. The boat survived the First World War and was sold for scrap in 1921.