|Ordered||21 November 1940|
|Laid down||15 October 1941|
|Launched||5 September 1942|
|Commissioned||14 November 1942|
|Recommissioned||15 December 1943|
|Decommissioned||15 May 1943|
|Fate||Sank in collision on 8 April 1943, raised scuttled 5 May 1945|
|Class and type||Type VIIC submarine|
|Height||9.60 m (31 ft 6 in)|
|Draught||4.74 m (15 ft 7 in)|
|Complement||4 officers, 40–56 enlisted|
|Identification codes:||M 50 883|
|Operations:||no war patrols|
|Victories:||no ships sunk|
German submarine U-733 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II. The submarine was laid down on 15 October 1941 at the Schichau-Werke yard at Danzig, launched on 5 September 1942, and commissioned on 14 November 1942 under the command of Oberleutnant zur See Wilhelm von Trotha.
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-733 had a displacement of 769 tonnes (757 long tons) when at the surface and 871 tonnes (857 long tons) while submerged. She 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).
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). 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-733 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, and two twin 2 cm (0.79 in) C/30 anti-aircraft guns. The boat had a complement of between forty-four and sixty.
On 8 April 1943, U-733 collided with Vorpostenboot V 313 outside Gotenhafen port and sank without fatalities. The next week, U-733 was raised and repaired in the Schichau yard. On 15 December 1943, U-733 was re-commissioned under the command of Oblt.z.S. Hans Hellmann. In May 1945, U-733 transferred to Flensburg, were the U-boat was attacked by US aircraft and scuttled after receiving heavy damage.