had a displacement of when at the surface and while submerged. U-711 had a total length of, a pressure hull length of, a beam of, a height of, and a draught of. The submarine was powered by two Germaniawerft F46 four-stroke, six-cylinder supercharged diesel engines producing a total of for use while surfaced, two AEG GU 460/8–27 double-acting electric motors producing a total of for use while submerged. She had two shafts and two propellers. The boat was capable of operating at depths of up to. The submarine had a maximum surface speed of and a maximum submerged speed of. When submerged, the boat could operate for at ; when surfaced, she could travel at. U-711 was fitted with five torpedo tubes, fourteen torpedoes, one SK C/35 naval gun, 220 rounds, removed in the summer of 1944, when she was fitted with the schnorkeland and two, twin C/30 anti-aircraft guns. The boat had a complement of between forty-four and sixty.
Service history
During her active service career, U-711 sank 2 ships and damaged a third. U-711 attacked and sank the British corvette 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. On 4 May 1945, U-711 was sunk by aircraft of the Fleet Air Arm during Operation Judgement, an attack on the depot ships 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, and 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.
As no-one was killed during her sinking U-711 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.
