German submarine U-711

German Type VIIC submarines had a displacement of 769 tonnes (757 long tons) when at the surface and 871 tonnes (857 long tons) while submerged.^[1] U-711 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).^[1]

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).^[1] 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-711 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, removed in the summer of 1944, when she was fitted with the schnorkeland and two, twin 2 cm (0.79 in) C/30 anti-aircraft guns. The boat had a complement of between forty-four and sixty.^[1]

During her active service career, U-711 sank 2 ships and damaged a third.

U-711 attacked and sank the British corvette HMS Bluebell on 17 February 1945 with an acoustic homing torpedo, which caused her depth charges to explode. Bluebell sank in less than 30 seconds and from her crew of 86 there was only one survivor.^[2]

On 4 May 1945, U-711 was sunk by aircraft of the Fleet Air Arm during Operation Judgement, an attack on the depot ships MS Black Watch and Senja anchored at Kilbotn, south of Harstad, Norway. This was the last air-raid of the war in Europe.

Avenger and Wildcat aircraft, from FAA Squadrons 846, 853 and 882, operating from the British escort carriers HMS Trumpeter, HMS Queen and HMS Searcher sank the Black Watch with 7 direct hits and 4 near misses. U-711, was moored alongside and was damaged but managed to sail away. The U-Boat had a harbour crew of eight on board, including the captain, who all survived although forty of her crew who were berthed on the depot ship were killed. The submarine later sank.

A few hours earlier Lange had received the signal from Germany ordering all U-boats to cease attacks on allied shipping.^[3]

U-711 took part in nine wolfpacks, namely:

• Wiking (1 August – 20 September 1943)
• Blitz (24 March – 5 April 1944)
• Keil (11 – 14 April 1944)
• Donner & Keil (24 April – 3 May 1944)
• Grimm (31 May – 6 June 1944)
• Trutz (8 June – 7 July 1944)
• Greif (3 – 18 August 1944)
• Rasmus (9 – 13 February 1945)
• Hagen (15 – 21 March 1945)

As no-one was killed during her sinking, U-711's location is not classed as a war grave and is a well-documented dive-site, lying at approximately 50 meters depth and only having minor damage.^[5]

• Helgason, Guðmundur. "The Type VIIC boat U-711". German U-boats of WWII - uboat.net. Retrieved 29 December 2014.
• Hofmann, Markus. "U 711". Deutsche U-Boote 1935-1945 - u-boot-archiv.de (in German). Retrieved 29 December 2014.