HMS L21

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History
Naval Ensign of the United Kingdom.svgUnited Kingdom
NameHMS L21
OrderedDecember 1916 [1]
Builder Vickers Limited, Barrow-in-Furness
Laid down15 September 1917
Launched11 October 1919 [1]
FateSold for scrapping, February 1939
General characteristics
Class and type L-class submarine
Displacement
  • 914 long tons (929 t) surfaced
  • 1,089 long tons (1,106 t) submerged
Length238 ft 7 in (72.7 m)
Beam23 ft 6 in (7.2 m)
Draught13 ft 3 in (4.0 m)
Installed power
  • 2,400  bhp (1,800 kW) (diesel)
  • 1,600 hp (1,200 kW) (electric)
Propulsion
Speed
  • 17  kn (31 km/h; 20 mph) surfaced
  • 10.5 kn (19.4 km/h; 12.1 mph) submerged
Range3,800  nmi (7,000 km; 4,400 mi) at 10 kn (19 km/h; 12 mph) on the surface
Test depth150 feet (45.7 m)
Complement38
Armament

HMS L21 was a L-class submarine built for the Royal Navy during World War I. The boat was not completed before the end of the war and was sold for scrap in 1939.

Contents

Design and description

L9 and its successors were enlarged to accommodate 21-inch (53.3 cm) torpedoes and more fuel. The submarine had a length of 238 feet 7 inches (72.7 m) overall, a beam of 23 feet 6 inches (7.2 m) and a mean draft of 13 feet 3 inches (4.0 m). [2] They displaced 914 long tons (929 t) on the surface and 1,089 long tons (1,106 t) submerged. The L-class submarines had a crew of 38 officers and ratings. [3] They had a diving depth of 150 feet (45.7 m). [4]

For surface running, the boats were powered by two 12-cylinder Vickers [5] 1,200- brake-horsepower (895 kW) diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a 600-horsepower (447 kW) electric motor. [2] They could reach 17 knots (31 km/h; 20 mph) on the surface and 10.5 knots (19.4 km/h; 12.1 mph) underwater. On the surface, the L class had a range of 3,800 nautical miles (7,000 km; 4,400 mi) at 10 knots (19 km/h; 12 mph). [4]

The boats were armed with four 21-inch torpedo tubes in the bow and two 18-inch (45 cm) in broadside mounts. They carried four reload torpedoes for the 21-inch tubes for a grand total of ten torpedoes of all sizes. [6] They were also armed with a 4-inch (102 mm) deck gun. [3]

Construction and career

HMS L21 was laid down on 15 September 1917 by Vickers at their Barrow-in-Furness shipyard, launched on 11 October 1918, and completed on 5 October 1920. L21 was sold in February 1939 and ran aground on the Isle of Arran, Bute whilst under tow to the breakers on 22 February 1939. She was refloated two days later on 24 February. [7]

Notes

  1. 1 2 Gardiner and Gray 1985, p. 93.
  2. 1 2 Gardiner & Gray, p. 93
  3. 1 2 Akermann, p. 165
  4. 1 2 Harrison, Chapter 11
  5. ↑ Harrison, Chapter 25
  6. ↑ Harrison, Chapter 27
  7. ↑ "News in Brief". The Times. No. 48239. London. 25 February 1939. col G, p. 9.

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References

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