German submarine U-978 was a World War II Type VIIC U-boat operated by Nazi Germany's Kriegsmarine . She completed the longest underwater patrol of World War II.
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-978 had a displacement of 769t when at the surface and 871t while submerged. She had a total length of 67.1m (220.1feet), a pressure hull length of 50.5m (165.7feet), a beam of 6.2m (20.3feet), a height of 9.6m (31.5feet), and a draught of 4.74m (15.55feet). The submarine was powered by two Germaniawerft F46 four-stroke, six-cylinder supercharged diesel engines producing a total of NaNPS for use while surfaced, two Brown, Boveri & Cie GG UB 720/8 double-acting electric motors producing a total of 750PS for use while submerged. She had two shafts and two 1.23abbr=onNaNabbr=on 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-978 was fitted with five 53.30NaN0 torpedo tubes (four fitted at the bow and one at the stern), fourteen torpedoes, one 8.82NaN2 SK C/35 naval gun, 220 rounds, and one twin 2sp=usNaNsp=us C/30 anti-aircraft gun. The boat had a complement of between forty-four and sixty.
U-978 was commissioned on 12 May 1943 and assigned to 5th U-boat Flotilla for crew training. On 1 August 1944, U-978 was assigned to 3rd U-boat Flotilla for operational service, and completed one patrol with that unit. On 4 September 1944 she was ordered to 11th U-boat Flotilla, beginning service on 5 September. During her second war patrol, U-978 completed the longest underwater Schnorchel patrol of World War II, lasting 68 days, under command of Guenther Pulst.[1] The record-breaking patrol began on 9 October 1944 when she left Bergen, Norway and ended on 16 December when she returned to Bergen from her patrol. This was two days longer than the famed underwater journey of to Argentina, shortly after Germany's surrender. During her two patrols U-978, did not sink any ships, but damaged one ship beyond repair, which measured .
U-978 survived the war as did her whole crew, and was surrendered at Trondheim on 9 May 1945. She was sunk on 11 December 1945 during Operation Deadlight by torpedoes at location 55.8333°N -15°W.