German submarine U-743 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine built for service during World War II. Her keel was laid down on 30 May 1942 by Schichau-Werke of Danzig. She was commissioned on 15 May 1943 with Oberleutnant zur See Helmut Kandzior in command.
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-743 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-743 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.
On 20 August 1944 U-743 entered Trondheim for schnorkel repairs. She left the next day and was never heard from again. On 10 September 1944 U-743 was declared missing.
U-743 was originally thought to have been sunk on 9 September 1944 at position 55.45°N -11.41°W by depth charges from and . This attack actually resulted in the sinking of .