|Ordered:||10 April 1941|
|Builder:||DeSchiMAG Seebeckwerft, Bremerhaven|
|Laid down:||27 April 1943|
|Commissioned:||29 April 1944|
|Fate:||sunk as target 21 December 1945 in position Coordinates:|
|Class and type:||Type IXC/40 submarine|
|Height:||9.60 m (31 ft 6 in)|
|Draught:||4.67 m (15 ft 4 in)|
|Test depth:||230 m (750 ft)|
|Complement:||4 officers, 44 enlisted|
|Sensors and |
|FuG 200 Hohentwiel|
|Identification codes:||M 17 549|
|Commanders:||Kptlt. Klaus Hornbostel|
U-801 was ordered in April 1941 from DeSchiMAG Seebeckwerft in Geestemünde under the yard number 716. Her keel was laid down on 27 April 1943 and the U-boat was launched sometime late in 1943. On 29 April 1944 she was commissioned into service under the command of Kapitänleutnant Klaus Hornbostel (Crew 34) in the 4th U-boat Flotilla.
German Type IXC/40 submarines were slightly larger than the original Type IXCs. U-806 had a displacement of 1,144 tonnes (1,126 long tons) when at the surface and 1,257 tonnes (1,237 long tons) while submerged. The U-boat had a total length of 76.76 m (251 ft 10 in), a pressure hull length of 58.75 m (192 ft 9 in), a beam of 6.86 m (22 ft 6 in), a height of 9.60 m (31 ft 6 in), and a draught of 4.67 m (15 ft 4 in). The submarine was powered by two MAN M 9 V 40/46 supercharged four-stroke, nine-cylinder diesel engines producing a total of 4,400 metric horsepower (3,240 kW; 4,340 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 1.92 m (6 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 18.3 knots (33.9 km/h; 21.1 mph) and a maximum submerged speed of 7.3 knots (13.5 km/h; 8.4 mph). When submerged, the boat could operate for 63 nautical miles (117 km; 72 mi) at 4 knots (7.4 km/h; 4.6 mph); when surfaced, she could travel 13,850 nautical miles (25,650 km; 15,940 mi) at 10 knots (19 km/h; 12 mph). U-806 was fitted with six 53.3 cm (21 in) torpedo tubes (four fitted at the bow and two at the stern), 22 torpedoes, one 10.5 cm (4.13 in) SK C/32 naval gun, 180 rounds, and a 3.7 cm (1.5 in) Flak M42 as well as two twin 2 cm (0.79 in) C/30 anti-aircraft guns. The boat had a complement of forty-eight.
After work up for deployment in the Baltic Sea, U-806 transferred to the 33rd U-boat Flotilla for front-line service on 19 October 1944. She left Kiel for her first - and only - war patrol on 23 October. On the way to her assigned operational area off Canada she stopped at Horten Naval Base and Kristiansand. While operating against convoy HX 327 in late December 1944, U-806 sank two ships, the British steamer Samtucky of 7,219 GRT, and the Canadian escort HMCS Clayoquot on 21 and 24 December respectively. An attack on another Canadian escort, HMCS Transcona, failed.
Two months later, U-806 returned to base via Norway, arriving in Flensburg on 27 February 1945. Spending the rest of the war in training, U-806 ran aground on Hatter Reef on 5 May 1945 and had to be towed free by a tug the next day. She arrived in Aarhus later that day in order to surrender to the Allies.
In June 1945 the U-boat was transferred to Loch Ryan via Fredericia, Kiel, and Wilhelmshaven, arriving in Scotland on 26 June. On 20 December 1945, as part of Operation Deadlight, U-806 left Loch Ryan under tow from HMS Masterful to be sunk by ORP Błyskawica by artillery.