SM UB-31 was a German Type UB II submarine or U-boat in the German Imperial Navy (German: Kaiserliche Marine) during World War I. The U-boat was ordered on 22 July 1915 and launched on 16 November 1915. She was commissioned into the German Imperial Navy on 25 March 1916 as SM UB-31.
SM UB-45, a u-boat similar to UB-31
|Ordered:||22 July 1915|
|Builder:||Blohm & Voss, Hamburg|
|Cost:||1,152,000 German Papiermark|
|Launched:||16 November 1915|
|Completed:||24 March 1916|
|Commissioned:||25 March 1916|
|Fate:||sunk 2 May 1918 by British warships|
|Class and type:||German Type UB II submarine|
|Draught:||3.69 m (12 ft 1 in)|
|Test depth:||50 m (160 ft)|
|Complement:||2 officers, 21 men|
|Notes:||42-second diving time|
The submarine sank 26 ships in 25 patrols. UB-31 was depth charged and sunk by British warships HMS Lord Leitrim, HMS Loyal Friend, and HMS Ocean Roamer in the English Channel on 2 May 1918. Alternatively she may have been sunk by a mine on that date.
A German Type UB II submarine, UB-31 had a displacement of 274 tonnes (270 long tons) when at the surface and 303 tonnes (298 long tons) while submerged. She had a total length of 36.90 m (121 ft 1 in), a beam of 4.37 m (14 ft 4 in), and a draught of 3.69 m (12 ft 1 in). The submarine was powered by two Benz six-cylinder diesel engines producing a total 270 metric horsepower (270 shp; 200 kW), two Siemens-Schuckert electric motors producing 280 metric horsepower (210 kW; 280 shp), and one propeller shaft. She was capable of operating at depths of up to 50 metres (160 ft).
The submarine had a maximum surface speed of 9.06 knots (16.78 km/h; 10.43 mph) and a maximum submerged speed of 5.71 knots (10.57 km/h; 6.57 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 7,030 nautical miles (13,020 km; 8,090 mi) at 5 knots (9.3 km/h; 5.8 mph). UB-31 was fitted with two 50 centimetres (20 in) torpedo tubes, four torpedoes, and one 8.8 cm (3.5 in) Uk L/30 deck gun. She had a complement of twenty-one crew members and two officers and a 42-second dive time.
Summary of raiding history
|9 April 1917||Kittiwake||1,866||Sunk|
|24 April 1917||Saint Jacques||415||Damaged|
|28 April 1917||Medina||12,350||Sunk|
|21 May 1917||City of Corinth||5,870||Sunk|
|15 June 1917||Teesdale||2,470||Damaged|
|17 June 1917||Stanhope||2,854||Sunk|
|5 July 1917||Ocean Swell||195||Sunk|
|6 July 1917||Ariadne Christine||3,550||Damaged|
|7 July 1917||Bellucia||4,368||Sunk|
|10 July 1917||Hildegard||622||Sunk|
|11 July 1917||Brunhilda||2,296||Sunk|
|1 August 1917||Alcyone||149||Sunk|
|1 August 1917||Laertes||4,541||Sunk|
|2 August 1917||Newlyn||4,019||Sunk|
|3 August 1917||Renee Marthe||50||Sunk|
|8 August 1917||Algerie||3,386||Damaged|
|8 September 1917||Elizabeth||58||Sunk|
|9 September 1917||Pluton||1,449||Sunk|
|19 October 1917||Waikawa||5,666||Sunk|
|20 October 1917||Colorado||7,165||Sunk|
|23 October 1917||Lepanto||6,389||Damaged|
|19 November 1917||Farn||4,393||Sunk|
|13 December 1917||Britannic||92||Sunk|
|15 December 1917||Sachem||5,354||Damaged|
|18 December 1917||Riversdale||2,805||Sunk|
|20 December 1917||Alice Marie||2,210||Sunk|
|20 December 1917||Eveline||2,605||Sunk|
|20 December 1917||Warsaw||608||Sunk|
|22 January 1918||Admiral Cochrane||6,565||Damaged|
|22 January 1918||Greatham||2,338||Sunk|
|24 January 1918||Elsa||3,581||Sunk|
|28 February 1918||Heenvliet||492||Sunk|
|20 March 1918||Boorara||6,570||Damaged|
|25 April 1918||Joseph||42||Sunk|
- "SM" stands for "Seiner Majestät" (English: His Majesty's) and combined with the U for Unterseeboot would be translated as His Majesty's Submarine.
- Tonnages are in gross register tons
- Rössler 1979, p. 64.
- Gröner 1991, pp. 23-25.
- Helgason, Guðmundur. "WWI U-boat commanders: Karl Vesper (Royal House Order of Hohenzollern)". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 1 February 2015.
- Helgason, Guðmundur. "WWI U-boat commanders: Thomas Bieber (Royal House Order of Hohenzollern)". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 1 February 2015.
- Helgason, Guðmundur. "WWI U-boat commanders: Wilhelm Braun". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 1 February 2015.
- Helgason, Guðmundur. "UB-31". U-Boat.net. Retrieved 8 May 2018.
- Helgason, Guðmundur. "Ships hit by UB-31". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 1 February 2015.
- Bendert, Harald (2000). Die UB-Boote der Kaiserlichen Marine, 1914-1918. Einsätze, Erfolge, Schicksal (in German). Hamburg: Verlag E.S. Mittler & Sohn GmbH. ISBN 3-8132-0713-7.
- Gröner, Erich; Jung, Dieter; Maass, Martin (1991). U-boats and Mine Warfare Vessels. German Warships 1815–1945. 2. Translated by Thomas, Keith; Magowan, Rachel. London: Conway Maritime Press. ISBN 0-85177-593-4.
- Rössler, Eberhard (1979). U-Bootbau bis Ende des 1. Weltkrieges, Konstruktionen für das Ausland und die Jahre 1935 – 1945. Die deutschen U-Boote und ihre Werften (in German). I. Munich: Bernard & Graefe. ISBN 3-7637-5213-7.