For other ships named German submarine U-21, see German submarine U-21 (disambiguation).
UB-21
CountryGerman Empire
Ordered30 April 1915[1]
BuilderBlohm & Voss, Hamburg[1]
Yard number251[1]
Launched26 September 1915[1]
Completed18 February 1916[1]
Commissioned20 February 1916
FateSunk as target 30 September 1920
SM UB-21
ClassType UB II submarine
Displacement
  • 263 t (259 long tons) surfaced
  • 292 t (287 long tons) submerged
Length
Beam
  • 4.36 m (14 ft 4 in) o/a
  • 3.85 m (13 ft) pressure hull
Draught3.70 m (12 ft 2 in)
Propulsion
Speed
  • 9.15 knots (16.95 km/h; 10.53 mph) surfaced
  • 5.81 knots (10.76 km/h; 6.69 mph) submerged
Range
  • 6,450 nmi (11,950 km; 7,420 mi) at 5 knots (9.3 km/h; 5.8 mph) surfaced
  • 45 nmi (83 km; 52 mi) at 4 knots (7.4 km/h; 4.6 mph) submerged
Test depth50 m (160 ft)
Complement2 officers, 21 men
Armament
Notes45-second diving time
SM UB-21
Partof
  • I Flotilla
  • 14 April 1916 – 1 February 1917
  • II Flotilla
  • 1 February – 10 September 1917
  • V Flotilla
  • 10 September 1917 – 29 April 1918
  • I Flotilla
  • 29 April – 7 October 1918
  • Training Flotilla
  • 7 October – 11 November 1918
Commanders
  • Kptlt. Ernst Hashagen[2]
  • 20 February – 26 November 1916
  • Oblt.z.S. Franz Walther[3]
  • 27 November 1916 – 9 September 1917
  • Oblt.z.S. Walter Scheffler[4]
  • 10 September 1917 – 28 April 1918
  • Oblt.z.S. Bruno Mahn[5]
  • 29 April – 7 October 1918
Operations26 patrols
Victories
  • 33 merchant ships sunk
    ()
  • 1 merchant ship damaged
    ()
  • 4 merchant ships taken as prize
    ()

SM UB-21[Note 1] was a German Type UB II submarine or U-boat in the Imperial German Navy (German: Kaiserliche Marine) during World War I. The U-boat was ordered on 30 April 1915 and launched on 26 September 1915. She was commissioned into the German Imperial Navy on 20 February 1916 as SM UB-21. The submarine sank 33 ships in 26 patrols for a total of .[6] Surrendered to Britain in accordance with the requirements of the Armistice with Germany, UB-21 was sunk as a target by HMS Terror in the Solent on 30 September 1920; the wreck was sold in 1970 and most had been cleared by 1998, although some remnants survive.[7]

Design

A Type UB II submarine, UB-21 had a displacement of 263 tonnes (259 long tons) when at the surface and 292 tonnes (287 long tons) while submerged. She had a total length of 36.13 m (118 ft 6 in), a beam of 4.36 m (14 ft 4 in), and a draught of 3.70 m (12 ft 2 in). The submarine was powered by two Körting six-cylinder, four-stroke diesel engines producing a total of 280 metric horsepower (280 hp; 210 kW), two Siemens-Schuckert electric motors producing 280 metric horsepower (210 kW; 280 hp), and one propeller shaft. She was capable of operating at depths of up to 50 metres (160 ft).[8]

The submarine had a maximum surface speed of 9.15 knots (16.95 km/h; 10.53 mph) and a maximum submerged speed of 5.81 knots (10.76 km/h; 6.69 mph). When submerged, she could operate for 45 nautical miles (83 km; 52 mi) at 4 knots (7.4 km/h; 4.6 mph); when surfaced, she could travel 6,650 nautical miles (12,320 km; 7,650 mi) at 5 knots (9.3 km/h; 5.8 mph). UB-21 was fitted with two 50 centimetres (20 in) torpedo tubes, four torpedoes, and one 5 cm (2.0 in) SK L/40 deck gun. She had a complement of twenty-one crew members and two officers and a 45-second dive time.[8]

Summary of raiding history

DateNameNationalityTonnage[Note 2]Fate[9]
5 May 1916HaraldSweden275Sunk
20 October 1916LeknaSweden204Sunk
20 October 1916RandiNorway467Sunk
20 October 1916SvartvikSweden322Sunk
21 October 1916FritzöeNorway641Captured as prize
21 October 1916GrönhaugNorway667Sunk
22 October 1916LondonDenmark184Sunk
22 October 1916ThorNorway372Sunk
3 November 1916PlutoNorway1,148Captured as prize
16 February 1917Lady AnnUnited Kingdom1,016Sunk
17 February 1917ExcelUnited Kingdom157Sunk
22 February 1917John MilesUnited Kingdom687Sunk
29 March 1917BywellUnited Kingdom1,522Sunk
31 March 1917NordenNorway776Captured as prize
29 April 1917VictoriaUnited Kingdom1,620Sunk
2 May 1917Rikard NoordrakNorway1,123Sunk
5 May 1917Edith CavellUnited Kingdom20Sunk
6 May 1917HaroldSweden1,679Sunk
8 May 1917Batavier IINetherlands157Captured as prize
6 June 1917S.N.A. 2France2,294Sunk
7 June 1917Sir FrancisUnited Kingdom1,991Sunk
21 July 1917TrelyonUnited Kingdom3,099Sunk
22 July 1917GlowUnited Kingdom1,141Sunk
23 July 1917VanlandSweden1,285Sunk
24 August 1917SpringhillUnited Kingdom1,507Sunk
18 October 1917AmsteldamUnited Kingdom1,233Sunk
19 October 1917GemmaUnited Kingdom1,385Sunk
23 November 1917OceanUnited Kingdom1,442Sunk
29 December 1917InvernessUnited Kingdom3,734Damaged
29 December 1917PatriaRussian Empire838Sunk
30 December 1917HerculesUnited Kingdom1,295Sunk
25 March 1918HerculesUnited Kingdom1,095Sunk
8 May 1918ConstantiaUnited Kingdom772Sunk
10 May 1918Anboto MendiSpain2,114Sunk
11 May 1918GothiaSweden1,826Sunk
12 May 1918HaslingdenUnited Kingdom1,934Sunk
4 July 1918MentorNorway539Sunk
26 September 1918PaulBelgium659Sunk

References

Notes

  1. ^ "SM" stands for "Seiner Majestät" (English: His Majesty's) and combined with the U for Unterseeboot would be translated as His Majesty's Submarine.
  2. ^ Tonnages are in gross register tons

Citations

  1. ^ Rössler 1979, p. 64.
  2. ^ 114. Retrieved 29 January 2015.
  3. ^ 385. Retrieved 29 January 2015.
  4. ^ 289. Retrieved 29 January 2015.
  5. ^ 194.html. Retrieved 29 January 2015.
  6. ^ Bendert 2000, p. 195.
  7. ^ Dodson, Aidan & Cant, Serena (2020). Spoils of War: the fate of enemy fleets after the two World Wars. Barnsley: Seaforth. pp. 49, 129. ISBN 978-1-5267-4198-1.
  8. ^ Gröner 1991, pp. 23–25.
  9. ^ ub21. Retrieved 29 January 2015.

Bibliography