SM UB-31

	SM UB-45, a U-boat similar to UB-31
History
German Empire
Name	UB-31
Ordered	22 July 1915
Builder	Blohm & Voss, Hamburg
Cost	1,152,000 German Papiermark
Yard number	255
Launched	16 November 1915
Completed	24 March 1916
Commissioned	25 March 1916
Fate	Sunk 2 May 1918
General characteristics
Class & type	Type UB II submarine
Displacement	274 t (270 long tons) surfaced; 303 t (298 long tons) submerged;
Length	36.90 m (121 ft 1 in) o/a ; 27.90 m (91 ft 6 in) pressure hull ;
Beam	4.37 m (14 ft 4 in) o/a; 3.85 m (12 ft 8 in) pressure hull;
Draught	3.69 m (12 ft 1 in)
Propulsion	1 × propeller shaft ; 2 × 6-cylinder diesel engine, 270 PS (200 kW; 270 bhp); 2 × electric motor, 280 PS (210 kW; 280 shp);
Speed	9.06 knots (16.78 km/h; 10.43 mph) surfaced; 5.71 knots (10.57 km/h; 6.57 mph) submerged;
Range	7,030 nmi (13,020 km; 8,090 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 depth	50 m (160 ft)
Complement	2 officers, 21 men
Armament	2 × 50 cm (19.7 in) torpedo tubes ; 4 × torpedoes (later 6); 1 × 8.8 cm (3.5 in) Uk L/30 deck gun ;
Notes	42-second diving time
Service record
Part of:	Baltic Flotilla; 16 May 1916 – 24 February 1917; Flandern Flotilla; 24 February 1917 – 2 May 1918;
Commanders:	Oblt.z.S. Karl Vesper; 18 March – 11 August 1916; Oblt.z.S. Thomas Bieber; 12 August 1916 – 31 January 1918; Oblt.z.S. Wilhelm Braun; 1 February – 2 May 1918;
Operations:	25 patrols
Victories:	27 merchant ships sunk ; (73,810 GRT); 8 merchant ships damaged ; (34,699 GRT);

Last updated August 01, 2025

SM UB-31^{[Note 1]} 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.

Design

A 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).^[2]

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.^[2]

Summary of raiding history

Date	Name	Nationality	Tonnage^{[Note 2]}	Fate^[7]
9 April 1917	Kittiwake	United Kingdom	1,866	Sunk
24 April 1917	Saint Jacques	France	415	Damaged
28 April 1917	Medina	United Kingdom	12,350	Sunk
21 May 1917	City of Corinth	United Kingdom	5,870	Sunk
15 June 1917	Teesdale	United Kingdom	2,470	Damaged
17 June 1917	Stanhope	United Kingdom	2,854	Sunk
5 July 1917	Ocean Swell	United Kingdom	195	Sunk
6 July 1917	Ariadne Christine	United Kingdom	3,550	Damaged
7 July 1917	Bellucia	United Kingdom	4,368	Sunk
10 July 1917	Hildegard	United States	622	Sunk
11 July 1917	Brunhilda	United Kingdom	2,296	Sunk
1 August 1917	Alcyone	United Kingdom	149	Sunk
1 August 1917	Laertes	United Kingdom	4,541	Sunk
2 August 1917	Newlyn	United Kingdom	4,019	Sunk
3 August 1917	Renee Marthe	France	49	Sunk
8 August 1917	Algerie	France	3,386	Damaged
8 September 1917	Elizabeth	United Kingdom	58	Sunk
9 September 1917	Pluton	Norway	1,449	Sunk
19 October 1917	Waikawa	United Kingdom	5,666	Sunk
20 October 1917	Colorado	United Kingdom	7,165	Sunk
23 October 1917	Lepanto	United Kingdom	6,389	Damaged
19 November 1917	Farn	United Kingdom	4,393	Sunk
13 December 1917	Britannic	United Kingdom	92	Sunk
15 December 1917	Sachem	United Kingdom	5,354	Damaged
18 December 1917	Riversdale	United Kingdom	2,805	Sunk
20 December 1917	Alice Marie	United Kingdom	2,210	Sunk
20 December 1917	Eveline	United Kingdom	2,605	Sunk
20 December 1917	Warsaw	United Kingdom	608	Sunk
22 January 1918	Admiral Cochrane	United Kingdom	6,565	Damaged
22 January 1918	Greatham	United Kingdom	2,338	Sunk
24 January 1918	Elsa	Norway	3,581	Sunk
28 February 1918	Heenvliet	Netherlands	492	Sunk
20 March 1918	Boorara	Australia	6,570	Damaged
24 April 1918	Agnete	United Kingdom	1,127	Sunk
25 April 1918	Joseph	France	42	Sunk

References

Notes

↑ "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

Citations

1 2 3 4 5 Rössler 1979, p. 64.
1 2 3 4 5 6 7 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.

Bibliography

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. Vol. 2. Translated by Thomas, Keith; Magowan, Rachel. London: Conway Maritime Press. ISBN 0-85177-593-4.
Rössler, Eberhard (1979). Die deutschen U-Boote und ihre Werften: eine Bilddokumentation über den deutschen U-Bootbau; in zwei Bänden (in German). Vol. I. Munich: Bernard & Graefe. ISBN 3-7637-5213-7.

External links

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[6] "SM" stands for "Seiner Majestät" (English: His Majesty's) and combined with the U for Unterseeboot would be translated as His Majesty's Submarine.

[tonnage-8] Tonnages are in gross register tons

[FOOTNOTERössler197964-1] 1 2 3 4 5 Rössler 1979, p. 64.

[FOOTNOTEGröner199123–25-2] 1 2 3 4 5 6 7 Gröner 1991, pp. 23–25.

[3] 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.

[4] 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.

[5] 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.

[7] Helgason, Guðmundur. "UB-31". U-Boat.net. Retrieved 8 May 2018.

[9] Helgason, Guðmundur. "Ships hit by UB-31". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 1 February 2015.

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v t e German Type UB II submarines
UB-18 UB-19 UB-20 UB-21 UB-22 UB-23 UB-24 UB-25 UB-26 UB-27 UB-28 UB-29 UB-30 UB-31 UB-32 UB-33 UB-34 UB-35 UB-36 UB-37 UB-38 UB-39 UB-40 UB-41 UB-42 UB-43 UB-44 UB-45 UB-46 UB-47
Preceded by: Type UB I Followed by: Type UB III
List of U-boats of Germany

v t e Shipwrecks and maritime incidents in May 1918
Shipwrecks	2 May: UB-31, Unity 5 May: Kyarra , UB-119 8 May: U-32 9 May: UC-78 10 May: UB-16, HMS Vindictive 11 May: Sant Anna, U-154, Verona 12 May: U-103, UB-72 13 May: UB-114, Zaanland 14 May: HMS Phoenix 17 May: U-35 18 May: Catapulte, Warrimoo, HMS Chesterfield 21 May: Rosalind 22 May: USS Wakiva II 23 May: Innisfallen, HMS Moldavia, UB-52 26 May: UB-74 30 May: SS Ausonia 31 May: HMS Fairy, USS President Lincoln, UC-75 Unknown date: UB-70
Other incidents	1 May: Prince Rupert 13 May: USS Hisko, USS Mexican, Nidd 22 May: USS Wabash 29 May: RMS Magdalena
1917 1918 1919 April 1918 June 1918

History
SM UB-45, a U-boat similar to UB-31
German Empire
Name	UB-31
Ordered	22 July 1915^[1]
Builder	Blohm & Voss, Hamburg ^[1]
Cost	1,152,000 German Papiermark ^[2]
Yard number	255^[1]
Launched	16 November 1915^[1]
Completed	24 March 1916^[1]
Commissioned	25 March 1916^[2]
Fate	Sunk 2 May 1918^[2]
General characteristics ^[2]
Class & type	Type UB II submarine
Displacement	274 t (270 long tons) surfaced 303 t (298 long tons) submerged
Length	36.90 m (121 ft 1 in) o/a 27.90 m (91 ft 6 in) pressure hull
Beam	4.37 m (14 ft 4 in) o/a 3.85 m (12 ft 8 in) pressure hull
Draught	3.69 m (12 ft 1 in)
Propulsion	1 × propeller shaft 2 × 6-cylinder diesel engine, 270 PS (200 kW; 270 bhp) 2 × electric motor, 280 PS (210 kW; 280 shp)
Speed	9.06 knots (16.78 km/h; 10.43 mph) surfaced 5.71 knots (10.57 km/h; 6.57 mph) submerged
Range	7,030 nmi (13,020 km; 8,090 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 depth	50 m (160 ft)
Complement	2 officers, 21 men
Armament	2 × 50 cm (19.7 in) torpedo tubes 4 × torpedoes (later 6) 1 × 8.8 cm (3.5 in) Uk L/30 deck gun
Notes	42-second diving time
Service record
Part of:	Baltic Flotilla 16 May 1916 – 24 February 1917 Flandern Flotilla 24 February 1917 – 2 May 1918
Commanders:	Oblt.z.S. Karl Vesper^[3] 18 March – 11 August 1916 Oblt.z.S. Thomas Bieber^[4] 12 August 1916 – 31 January 1918 Oblt.z.S. Wilhelm Braun^[5] 1 February – 2 May 1918
Operations:	25 patrols
Victories:	27 merchant ships sunk (73,810 GRT) 8 merchant ships damaged (34,699 GRT)