German submarine U-31 (1936)

German submarine U-31 was a Type VIIA U-boat of Nazi Germany's Kriegsmarine during World War II. She was laid down on 1 March 1936 as yard number 912, launched on 25 September and commissioned on 28 December 1936.[1]

For other ships with the same name, see German submarine U-31.
U-33, a typical Type VIIA boat
History
Nazi Germany
Name: U-31
Ordered: 1 April 1935
Builder: AG Weser, Bremen
Cost: 4,189,000 Reichsmark
Yard number: 912
Laid down: 1 March 1936
Launched: 25 September 1936
Commissioned: 28 December 1936
Recommissioned: 30 July 1940
Decommissioned: 24 March 1940
Fate:
  • Sunk, 11 March 1940, raised
  • sunk again 2 November 1940
General characteristics
Class and type: Type VIIA submarine
Displacement:
  • 626 t (616 long tons) surfaced
  • 745 t (733 long tons) submerged
Length:
  • 64.51 m (211 ft 8 in) o/a
  • 45.50 m (149 ft 3 in) pressure hull
Beam:
  • 5.85 m (19 ft 2 in) o/a
  • 4.70 m (15 ft 5 in) pressure hull
Height: 9.50 m (31 ft 2 in)
Draught: 4.37 m (14 ft 4 in)
Installed power:
  • 2,100–2,310 PS (1,540–1,700 kW; 2,070–2,280 bhp) (diesels)
  • 750 PS (550 kW; 740 shp) (electric)
Propulsion:
Range:
  • 6,200 nmi (11,500 km; 7,100 mi) at 10 knots (19 km/h; 12 mph) surfaced
  • 73–94 nmi (135–174 km; 84–108 mi) at 4 knots (7.4 km/h; 4.6 mph) submerged
Test depth:
  • 220 m (720 ft)
  • Crush depth: 230–250 m (750–820 ft)
Complement: 4 officers, 40–56 enlisted
Sensors and
processing systems:		 Gruppenhorchgerät
Armament:
Service record[1][2]
Part of:
Identification codes: M 28 961
Commanders:
  • Kptlt. Rolf Dau
  • 28 December 1936 – 8 November 1938
  • Kptlt. Johannes Habekost
  • 8 November 1938 – 11 March 1940
  • Wilfried Prellberg
  • 8 July 1940 – 2 November 1940
Operations:
  • Seven:
  • 1st patrol: 27 August – 2 September 1939
  • 2nd patrol: 9 September – 2 October 1939
  • 3rd patrol: 21–31 October 1939
  • 4th patrol: 19 November – 11 December 1939
  • 5th patrol: 15 January – 4 February 1940
  • 6th patrol: 16 September – 8 October 1940
  • 7th patrol: 19 October – 2 November 1940
Victories:
  • 11 commercial ships sunk (27,751 GRT)
  • two auxiliary warships sunk (160 GRT)
  • one warship damaged (33,950 GRT)

Design

As one of the first ten German Type VII submarines later designated as Type VIIA submarines, U-31 had a displacement of 626 tonnes (616 long tons) when at the surface and 745 tonnes (733 long tons) while submerged.[3] She had a total length of 64.51 m (211 ft 8 in), a pressure hull length of 45.50 m (149 ft 3 in), a beam of 5.85 m (19 ft 2 in), a height of 9.50 m (31 ft 2 in), and a draught of 4.37 m (14 ft 4 in). The submarine was powered by two MAN M 6 V 40/46 four-stroke, six-cylinder diesel engines producing a total of 2,100 to 2,310 metric horsepower (1,540 to 1,700 kW; 2,070 to 2,280 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).[3]

The submarine had a maximum surface speed of 17 knots (31 km/h; 20 mph) and a maximum submerged speed of 8 knots (15 km/h; 9.2 mph).[3] When submerged, the boat could operate for 73–94 nautical miles (135–174 km; 84–108 mi) at 4 knots (7.4 km/h; 4.6 mph); when surfaced, she could travel 6,200 nautical miles (11,500 km; 7,100 mi) at 10 knots (19 km/h; 12 mph). U-31 was fitted with five 53.3 cm (21 in) torpedo tubes (four fitted at the bow and one at the stern), eleven torpedoes, one 8.8 cm (3.46 in) SK C/35 naval gun, 220 rounds, and an anti-aircraft gun. The boat had a complement of between forty-four and sixty.[3]

Service history

During her career U-31 was involved in seven war patrols.

First patrol

U-31 was one of the few ocean-going submarines deployed to the Baltic Sea instead of the Atlantic Ocean on the eve of World War II. Departing Memel under the command of Johannes Habekost on 27 August, this uneventful trip was concluded quickly with the rapid destruction of the Polish Navy and the boat put in at Wilhelmshaven on 2 September.[4]

Second patrol

After her quick return to Germany, U-31 became one of three Type VII reserve boats, going to sea again when Karl Dönitz ordered a redeployment of the U-boat force on 8 September. Ordered along with U-35 to save time by directly proceeding to the Atlantic via the English Channel,[5] she attacked the first convoy of World War II, OB 4 on 16 September 1939, sinking the British steamer SS Aviemore.[6] Habekost had found the convoy the day before and per orders reported the convoy's location, course and speed to Dönitz. Excited by this first reliable convoy report, he ordered all available boats to converge and attack the convoy. U-31 maneuvered into attack position and in the nighttime hours made an attack. Thinking he had sunk two ships, Habekost had however suffered torpedo failure, and thus only the 4,000 ton Aviemore was actually sunk out of the convoy by U-31. U-31 would later sink the slightly larger Hazelside, of 4,646 tons, on 24 September before concluding the patrol and returning to Wilhelmshaven on 2 October 1939.[7]

First sinking

On 11 March 1940 U-31 was sunk in the Schillig Roads near buoy 12 (53°37′N 08°10′E) by four bombs from a Bristol Blenheim, O of No. 82 Squadron RAF, with the loss of 58 lives. The U-boat had been on trials and carried eleven workers from the shipyard and two assistants to the flotilla engineer in addition to her regular complement.[8]

The U-boat was raised later that month, repaired and returned to service on 30 July 1940 with Kptlt. Prellberg in command.[1][9][10]

Second sinking

U-31 was sunk again on 2 November 1940, north-west of Ireland, by depth charges from the British destroyer HMS Antelope, which picked up 44 survivors (or 43, sources vary), from the crew of 46.[1][11]

In U-31's entire career she sank eleven ships, totalling 27,751 gross register tons (GRT), and one auxiliary warship of 160 GRT. A mine laid by U-31 damaged the British battleship HMS Nelson of 33,950 tons.[1]

Summary of raiding history
DateName of ShipNationalityTonnage[Note 1]Fate[12]
16 September 1939 Aviemore  United Kingdom 4,060 Sunk
24 September 1939 Hazelside  United Kingdom 4,646 Sunk
1 December 1939 Arcturus  Norway 1,277 Sunk
3 December 1939 Ove Taft  Denmark 2,135 Sunk
4 December 1939 HMS Nelson  Royal Navy 33,950 Damaged (mine)
4 December 1939 Primula  Norway 1,024 Sunk
6 December 1939 Agu  Estonia 1,575 Sunk
6 December 1939 Vinga  Sweden 1,974 Sunk
23 December 1939 HMS Glen Albyn  Royal Navy 82 Sunk (mine)
23 December 1939 HMS Promotive  Royal Navy 78 Sunk (mine)
22 September 1940 Union Jack  Faroe Islands 81 Sunk
27 September 1940 Vestvard  Norway 4,319 Sunk
29 October 1940 Matina  United Kingdom 5,389 Sunk

References

Notes
  1. Merchant ship tonnages are in gross register tons. Military vessels are listed by tons displacement.

Citations
  1. Helgason, Guðmundur. "The Type VIIA boat U-31". German U-boats of WWII - uboat.net. Retrieved 19 December 2009.
  2. Helgason, Guðmundur. "War Patrols by German U-boat U-31". German U-boats of WWII - uboat.net. Retrieved 19 December 2009.
  3. Gröner, Jung & Maass 1991, pp. 43–44.
  4. Helgason, Guðmundur. "Patrol info for U-31". German U-boats of WWII - uboat.net. Retrieved 6 November 2017.
  5. Blair, page 84
  6. Helgason, Guðmundur. "Aviemore (Steam merchant)". German U-boats of WWII - uboat.net. Retrieved 19 December 2009.
  7. Helgason, Guðmundur. "Patrol info for U-31". German U-boats of WWII - uboat.net. Retrieved 6 November 2017.
  8. Busch & Röll 1999, p. 17.
  9. Kemp 1999, p. 64.
  10. Rohwer, Jürgen; Gerhard Hümmelchen. "Seekrieg 1940, Märtz". Württembergische Landesbibliothek Stuttgart (in German). Retrieved 6 March 2015.
  11. Kemp 1999, p. 67.
  12. Helgason, Guðmundur. "Ships hit by U-31". German U-boats of WWII - uboat.net. Retrieved 8 December 2014.

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). Deutsche U-Boot-Verluste von September 1939 bis Mai 1945 [German U-boat losses from September 1939 to May 1945]. Der U-Boot-Krieg (in German). IV. Hamburg, Berlin, Bonn: Mittler. ISBN 3-8132-0514-2.
  • 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.
  • Kemp, Paul (1999). U-Boats Destroyed - German Submarine Losses in the World Wars. London: Arms & Armour. ISBN 1-85409-515-3.
  • Helgason, Guðmundur. "The Type VIIA boat U-31". German U-boats of WWII - uboat.net. Retrieved 8 December 2014.
  • Hofmann, Markus. "U 31". Deutsche U-Boote 1935-1945 - u-boot-archiv.de (in German). Retrieved 7 December 2014.

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