German submarine U-631

German submarine U-631 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II. She was laid down on 5 September 1941 by Blohm & Voss, Hamburg as yard number 607, launched on 27 May 1942 and commissioned on 16 July 1942 under Oberleutnant zur See Jürgen Krüger.

History
Nazi Germany
Name	U-631
Ordered	15 August 1940
Builder	Blohm & Voss, Hamburg
Yard number	607
Laid down	5 September 1941
Launched	27 May 1942
Commissioned	16 July 1942
Fate	Sunk on 17 October 1943 in the North Atlantic in position 58°13′N 32°29′W, by depth charges from HMS Sunflower.
General characteristics
Class and type	Type VIIC submarine
Displacement	769 tonnes (757 long tons) surfaced 871 t (857 long tons) submerged
Length	67.10 m (220 ft 2 in) o/a 50.50 m (165 ft 8 in) pressure hull
Beam	6.20 m (20 ft 4 in) o/a 4.70 m (15 ft 5 in) pressure hull
Draught	4.74 m (15 ft 7 in)
Installed power	2,800–3,200 PS (2,100–2,400 kW; 2,800–3,200 bhp) (diesels) 750 PS (550 kW; 740 shp) (electric)
Propulsion	2 shafts 2 × diesel engines 2 × electric motors
Speed	17.7 knots (32.8 km/h; 20.4 mph) surfaced 7.6 knots (14.1 km/h; 8.7 mph) submerged
Range	8,500 nmi (15,700 km; 9,800 mi) at 10 knots (19 km/h; 12 mph) surfaced 80 nmi (150 km; 92 mi) at 4 knots (7.4 km/h; 4.6 mph) submerged
Test depth	230 m (750 ft) Crush depth: 250–295 m (820–968 ft)
Complement	4 officers, 40–56 enlisted
Armament	5 × 53.3 cm (21 in) torpedo tubes (four bow, one stern) 14 × torpedoes or 26 TMA mines 1 × 8.8 cm (3.46 in) deck gun (220 rounds) 1 × twin 2 cm (0.79 in) C/30 anti-aircraft gun
Service record
Part of:	5th U-boat Flotilla 16 July – 31 December 1942 9th U-boat Flotilla 1 January – 17 October 1943
Identification codes:	M 22 458
Commanders:	Oblt.z.S. Jürgen Krüger 16 July 1942 – 17 October 1943
Operations:	3 patrols: 1st patrol: 19 December 1942 – 4 February 1943 2nd patrol: 6 March – 11 May 1943 3rd patrol: 18 September – 17 October 1943
Victories:	2 merchant ships sunk (9,136 GRT)

Design

German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-631 had a displacement of 769 tonnes (757 long tons) when at the surface and 871 tonnes (857 long tons) while submerged. She had a total length of 67.10 m (220 ft 2 in), a pressure hull length of 50.50 m (165 ft 8 in), a beam of 6.20 m (20 ft 4 in), a height of 9.60 m (31 ft 6 in), and a draught of 4.74 m (15 ft 7 in). The submarine was powered by two Germaniawerft F46 four-stroke, six-cylinder supercharged diesel engines producing a total of 2,800 to 3,200 metric horsepower (2,060 to 2,350 kW; 2,760 to 3,160 shp) for use while surfaced, two BBC GG UB 720/8 double-acting electric motors producing a total of 750 metric horsepower (550 kW; 740 shp) for use while submerged. She had two shafts and two 1.23 m (4 ft) propellers. The boat was capable of operating at depths of up to 230 metres (750 ft).

The submarine had a maximum surface speed of 17.7 knots (32.8 km/h; 20.4 mph) and a maximum submerged speed of 7.6 knots (14.1 km/h; 8.7 mph). When submerged, the boat could operate for 80 nautical miles (150 km; 92 mi) at 4 knots (7.4 km/h; 4.6 mph); when surfaced, she could travel 8,500 nautical miles (15,700 km; 9,800 mi) at 10 knots (19 km/h; 12 mph). U-631 was fitted with five 53.3 cm (21 in) torpedo tubes (four fitted at the bow and one at the stern), fourteen torpedoes, one 8.8 cm (3.46 in) SK C/35 naval gun, 220 rounds, and one twin 2 cm (0.79 in) C/30 anti-aircraft gun. The boat had a complement of between forty-four and sixty.

Service history

The boat's career began with training at 5th U-boat Flotilla on 16 July 1942, followed by active service on 1 January 1943 as part of the 9th Flotilla for the remainder of her service. In three patrols she sank two merchant ships, for a total of 9,136 gross register tons (GRT).

Fate

U-631 was sunk on 17 October 1943 in the North Atlantic SE of Cape Farewell, Greenland, in position 58°13′N 32°29′W, by depth charges from British corvette HMS Sunflower. All crew members died.

Wolfpacks

U-631 took part in seven wolfpacks, namely:

• Falke (28 December 1942 – 19 January 1943)
• Landsknecht (19 – 28 January 1943)
• Stürmer (11 – 20 March 1943)
• Seewolf 2 (21 – 30 March 1943)
• Meise (11 – 27 April 1943)
• Rossbach (27 September – 9 October 1943)
• Schlieffen (14 – 17 October 1943)

Summary of raiding history

Date	Ship Name	Nationality	Tonnage (GRT)	Fate
29 December 1942	Ingerfem	Norway	3,978	Sunk
17 March 1943	Terkoelei	Netherlands	5,158	Sunk

Bibliography

• Busch, Rainer; Röll, Hans-Joachim (1999). German U-boat commanders of World War II: a biographical dictionary. Translated by Brooks, Geoffrey. London, Annapolis, Md: Greenhill Books, Naval Institute Press. ISBN 1-55750-186-6.
• Busch, Rainer; Röll, Hans-Joachim (1999). Der U-Boot-Krieg, 1939-1945: Deutsche U-Boot-Verluste von September 1939 bis Mai 1945 [German U-boat losses from September 1939 to May 1945] (in German). Vol. IV. Hamburg, Berlin, Bonn: Mittler. ISBN 3-8132-0514-2.
• Gröner, Eric; Jung, Dieter; Maass, Martin (1991). German Warships 1815-1945: U-boats and Mine Warfare Vessels. Vol. 2. Translated by Thomas, Keith; Magowan, Rachel. London: Conway Maritime Press. ISBN 0-85177-593-4.
• Sharpe, Peter (1998). U-Boat Fact File. Great Britain: Midland Publishing. ISBN 1-85780-072-9.

External links

• Helgason, Guðmundur. "The Type VIIC boat U-631". German U-boats of WWII - uboat.net. Retrieved 29 December 2014.