SM U-21 (Austria-Hungary)

SM U-21 loads a torpedo during World War I.
SM U-21 loads a torpedo during World War I.
History
Austria-Hungary
NameSM U-21
Ordered27 March 1915[1]
BuilderPola Navy Yard, Pola[3]
Laid downMid 1915[2]
Launched15 August 1916[3]
Commissioned15 August 1917[2]
FateCeded to Italy, scrapped 1920[3]
Service record
Commanders:
  • Josef Holub
  • 29 June 1916 – 24 February 1917[4]
  • Reichsfreiherr Hugo von Seyffertitz
  • 15 August 1917 – 24 March 1918
  • Robert Dürrigl
  • 24 March – 28 August 1918
  • Ladislaus Csicsery von Csicser
  • 28 August – 31 October 1918
Victories: None[4]
General characteristics
TypeU-20-class submarine
Displacement
  • 173 t (170 long tons), surfaced
  • 210 t (210 long tons), submerged[3]
Length127 ft 2 in (38.76 m)[3]
Beam13 ft (4.0 m)[3]
Draft9 ft (2.7 m)[3]
Propulsion
Speed
  • 12 knots (22 km/h) surfaced
  • 9 knots (17 km/h) submerged[3]
Range
  • 1,400 nautical miles (2,600 km) at 10 knots (19 km/h) surfaced[5]
  • 23 nautical miles (43 km) at 8 knots (15 km/h) submerged
Complement18[3]
Armament

SM U-21 or U-XXI was a U-20-class submarine or U-boat built for and operated by the Austro-Hungarian Navy (German: Kaiserliche und Königliche Kriegsmarine or K.u.K. Kriegsmarine) during the First World War. The design for U-21 was based on submarines of the Royal Danish Navy's Havmanden class (three of which had been built in Austria-Hungary), and was largely obsolete by the beginning of the war.

U-21 was just over 127 feet (39 m) long and was armed with two bow torpedo tubes, a deck gun, and a machine gun. Construction on U-21 began in mid 1915 and the boat was launched in September 1916. After suffering damage during a diving trial in January 1917, U-21 underwent seven months of repairs before her commissioning in August 1917.

The U-boat conducted patrols off the Albanian coast in October 1917, but experienced the failure of the seal on her main hatch. The repairs kept the boat out of action until June 1918. But in July a piston in her diesel engine broke, knocking the submarine out of the rest of the war. At the end of World War I, U-21 was ceded to Italy as a war reparation and scrapped in 1920. U-21 had no wartime successes.

  1. ^ Halpern, p. 382.
  2. ^ a b "Tengeralattjárók" (PDF) (in Hungarian). Imperial and Royal Navy Association. p. 20. Archived from the original (PDF) on 11 October 2021. Retrieved 2 February 2009.
  3. ^ a b c d e f g h i j k Gardiner, p. 343.
  4. ^ a b Helgason, Guðmundur. "WWI U-boats: KUK U21". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 29 November 2008.
  5. ^ Gardiner, p. 354.