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U-864

History
Nazi Germany
Name: U-864
Ordered: 5 June 1941
Builder: DeSchiMAG AG Weser, Bremen
Yard number: 1070
Laid down: 15 October 1942
Launched: 12 August 1943
Commissioned: 9 December 1943
Fate: Sunk with all hands, 9 February 1945 by HMS Venturer, North Sea west of Bergen
General characteristics
Class and type: Type IXD2 U-boat
Displacement:
  • 1,610 t (1,580 long tons) surfaced
  • 1,799 t (1,771 long tons) submerged
Length:
Beam:
  • 7.50 m (24 ft 7 in) o/a
  • 4.40 m (14 ft 5 in) pressure hull
Height: 10.20 m (33 ft 6 in)
Draught: 5.35 m (17 ft 7 in)
Propulsion:
  • 9,000 PS (8,900 shp; 6,600 kW) surfaced
  • 1,000 PS (990 shp; 740 kW) submerged
Speed:
  • 20.8 knots (38.5 km/h; 23.9 mph) surfaced
  • 6.9 knots (12.8 km/h; 7.9 mph) submerged
Range:
  • 12,750 nmi (23,610 km; 14,670 mi) at 10 knots (19 km/h; 12 mph) surfaced
  • 57 nmi (106 km; 66 mi) at 4 knots (7.4 km/h; 4.6 mph) submerged
Test depth: Calculated crush depth: 230 m (754 ft 7 in)
Boats & landing
craft carried:
2 dinghies
Complement: 55–63 officers & ratings
Armament:
Service record
Part of:
Commanders:
Operations: 1 patrol: 7–9 February 1945

The German submarine U-864 was a Type IX U-boat of Nazi Germany's Kriegsmarine in World War II. She departed from Kiel on 5 December 1944 on her last mission, to transport to Japan a large quantity of mercury and parts and engineering drawings for German jet fighters. While returning to Bergen, Norway to repair a misfiring engine, the U-864 was detected and sunk on 9 February 1945 by the British submarine HMS Venturer, killing all 73 on board. It is the only instance in the history of naval warfare where one submarine intentionally sank another while both were submerged.

The shipwreck was located in March 2003 by the Royal Norwegian Navy 2 nmi (3.7 km; 2.3 mi) west of the island of Fedje in the North Sea, at 150 metres (490 ft). The mercury had been seeping out of rusted containers, contaminating the region and sea life. One study recommended entombing the wreck under a layer of sand as well as gravel and concrete. The Norwegian government instead awarded a contract to a salvage company to raise the wreck; however, the proposed operation was put on hold pending additional studies.

German Type IXD2 submarines were considerably larger than the original Type IXs. The U-864 had a displacement of 1,610 tonnes (1,580 long tons) when at the surface and 1,799 tonnes (1,771 long tons) while submerged. The U-boat had a total length of 87.58 m (287 ft 4 in), a pressure hull length of 68.50 m (224 ft 9 in), a beam of 7.50 m (24 ft 7 in), a height of 10.20 m (33 ft 6 in), and a draught of 5.35 m (17 ft 7 in). The submarine was powered by two MAN M 9 V 40/46 supercharged four-stroke, nine-cylinder diesel engines plus two MWM RS34.5S six-cylinder four-stroke diesel engines for cruising, producing a total of 9,000 metric horsepower (6,620 kW; 8,880 shp) for use while surfaced, two Siemens-Schuckert 2 GU 345/34 double-acting electric motors producing a total of 1,000 shaft horsepower (1,010 PS; 750 kW) for use while submerged. She had two shafts and two 1.85 m (6 ft) propellers. The boat was capable of operating at depths of up to 200 metres (660 ft).


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