Name U-31 Cost 4,189,000 Reichsmark Laid down 1 March 1936 Construction started 1 March 1936 Length 64 m Beam 5.85 m Part of 2nd U-boat Flotilla | Ordered 1 April 1935 Yard number 912 Commissioned 28 December 1936 Launched 25 September 1936 Draft 4.37 m Builder AG Weser | |
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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.
Contents
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. 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).
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). 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.
Service history
During her career U-31 was involved in seven war patrols, and attacked the first convoy of World War II, OB-4 on 16 September 1939, sinking the British steamer SS Aviemore.
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.
The U-boat was raised later that month, repaired and returned to service on 30 July 1940 with Kptlt. Prellberg in command.
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.
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.