German World War II submarine
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|
| History |
|---|
 Nazi Germany |
|---|
| Name | U-731 |
| Ordered | 21 November 1940 |
| Builder | Schichau-Werke, Danzig |
| Yard number | 1522 |
| Laid down | 1 October 1941 |
| Launched | 25 July 1942 |
| Commissioned | 3 October 1942 |
| Fate | Sunk on 15 May 1944 near Tangier by British patrol vessels |
| General characteristics |
|---|
| Class and type | Type VIIC submarine |
| Displacement |
- 769 t (757 long tons) surfaced
- 871 t (857 long tons) submerged
|
| Length | |
| Beam |
- 6.20 m (20 ft 4 in) (o/a)
- 4.70 m (15 ft 5 in) (pressure hull)
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| Height | 9.60 m (31 ft 6 in) |
| 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)
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| Propulsion | |
| Speed |
- 17.7 knots (32.8 km/h; 20.4 mph) surfaced
- 7.6 knots (14.1 km/h; 8.7 mph) submerged
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| 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
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| Test depth | |
| Complement | 4 officers, 40–56 enlisted |
| Armament | |
| Service record |
| Part of: |
|
| Identification codes: |
M 50 791 |
| Commanders: |
- Oblt.z.S. Werner Techand
- 3 October 1942 – 30 November 1943
- Oblt.z.S. Graf Alexander von Keller
- 1 December 1943 – 15 May 1944
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| Operations: |
- 4 patrols:
- 1st patrol:
- 29 April – 12 June 1943
- 2nd patrol:
- 29 August – 1 November 1943
- 3rd patrol:
- 19 December 1943 – 18 February 1944
- 4th patrol:
- 18 April – 15 May 1944
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| Victories: |
None |
German submarine U-731 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II. The submarine was laid down on 1 October 1941 at the Schichau-Werke yard at Danzig, launched on 25 July 1942, and commissioned on 3 October 1942 under the command of Oberleutnant zur See Werner Techand.
Attached to 8th U-boat Flotilla based at Kiel, U-731 completed her training period on 30 April 1943 and was assigned to front-line service.
Design
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-731 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 AEG GU 460/8–27 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-731 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 two twin 2 cm (0.79 in) C/30 anti-aircraft guns. The boat had a complement of between forty-four and sixty.
Service history
On the fourth and final war patrol, U-731 was detected on 15 May 1944 by two Catalinas, P-14 and P-1, of VP-63 off Tangiers, when the U-boat tried to force the Strait of Gibraltar. Two British patrol craft, HMS Kilmarnock and HMS Blackfly, received reports of the U-boat and attacked with hedgehogs. U-731 was sunk in position 35°54′N 5°45′W / 35.900°N 5.750°W / 35.900; -5.750; all 54 crew members perished in the attack.
