German submarine U-736 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine built for service during World War II. Her keel was laid down on 29 November 1941 by Schichau-Werke of Danzig. She was commissioned on 16 January 1943 with Oberleutnant zur See Reinhard Reff in command.
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-736 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 AEG GU 460/8–27 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-736 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 two twin 2sp=usNaNsp=us C/30 anti-aircraft guns. The boat had a complement of between forty-four and sixty.
U-736 was severely damaged on 24 May 1944 by a Consolidated Liberator from No. 224 Squadron RAF, aircraft letter 'C', and then shot down a British Vickers Wellington aircraft.
U-736 was sunk on 6 August 1944 in the Bay of Biscay west of St. Nazaire, in position 47.3167°N -20°W, by Squid depth charges from ; there were 19 survivors and 28 dead.
The U-boat captain, Oberleutnant zur See Reinhard Reff, had fired a torpedo at HMS Loch Killin and the periscope was spotted by a port lookout. Action stations rang out through the ship and depth charges shot out in record time. The torpedo was destroyed by the explosion, which was so violent that it forced the damaged U-736 to surface under the stern of the frigate. For a few minutes both vessels were locked together and the survivors of the crew scrambled onto the quarterdeck of Loch Killin to the bewilderment of the frigate's crew. Then U-736 slipped away taking the other crew members to the bottom. The prisoners were disembarked to another warship returning to England and Loch Killin continued on patrol.