HMS E21

HMS E21 was a British E class submarine built by Vickers, Barrow-in-Furness. She was launched on 24 July 1915 and commissioned on 1 October 1915. E21 was sold on 14 December 1921.

History
United Kingdom
Name	E21
Builder	Vickers, Barrow
Launched	24 July 1915
Commissioned	1 October 1915
Fate	Sold, 14 December 1921
General characteristics
Class and type	E-class submarine
Displacement	662 long tons (673 t) surfaced 807 long tons (820 t) submerged
Length	181 ft (55 m)
Beam	15 ft (4.6 m)
Propulsion	2 × 800 hp (597 kW) diesel 2 × 420 hp (313 kW) electric 2 screws
Speed	15 knots (28 km/h; 17 mph) surfaced 10 knots (19 km/h; 12 mph) submerged
Range	3,000 nmi (5,600 km) at 10 kn (19 km/h; 12 mph) surfaced 65 nmi (120 km) at 5 kn (9.3 km/h; 5.8 mph) submerged
Complement	3 officers, 28 ratings
Armament	5 × 18 inch (450 mm) torpedo tubes (2 bow, 2 beam, 1 stern) 1 × 12-pounder gun

Design

Like all post-E8 British E-class submarines, E21 had a displacement of 662 long tons (673 t) at the surface and 807 long tons (820 t) while submerged. She had a total length of 180 feet (55 m)^[1] and a beam of 22 feet 8.5 inches (6.922 m). She was powered by two 800 horsepower (600 kW) Vickers eight-cylinder two-stroke diesel engines and two 420 horsepower (310 kW) electric motors.^[2][3] The submarine had a maximum surface speed of 16 knots (30 km/h; 18 mph) and a submerged speed of 10 knots (19 km/h; 12 mph). British E-class submarines had fuel capacities of 50 long tons (51 t) of diesel and ranges of 3,255 miles (5,238 km; 2,829 nmi) when travelling at 10 knots (19 km/h; 12 mph).^[1] E21 was capable of operating submerged for five hours when travelling at 5 knots (9.3 km/h; 5.8 mph).

E21 was armed with a 12-pounder QF gun mounted forward of the conning tower. She had five 18 inch (450 mm) torpedo tubes, two in the bow, one either side amidships, and one in the stern; a total of 10 torpedoes were carried.^[2]

E-Class submarines had wireless systems with 1 kilowatt (1.3 hp) power ratings; in some submarines, these were later upgraded to 3 kilowatts (4.0 hp) systems by removing a midship torpedo tube. Their maximum design depth was 100 feet (30 m) although in service some reached depths of below 200 feet (61 m). Some submarines contained Fessenden oscillator systems.^[1]

Crew

Her complement was three officers and 28 men.^[1]