German submarine U-633

German submarine U-633 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II. She was laid down on 22 September 1941 by Blohm & Voss, Hamburg as yard number 609, launched on 10 June 1942 and commissioned on 30 July 1942 under Oberleutnant zur See Bernhard Müller.

Design
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-633 had a displacement of 769 t when at the surface and 871 t while submerged. She had a total length of 67.10 m, a pressure hull length of 50.50 m, a beam of 6.20 m, a height of 9.60 m, and a draught of 4.74 m. The submarine was powered by two Germaniawerft F46 four-stroke, six-cylinder supercharged diesel engines producing a total of 2800 to 3200 PS for use while surfaced, two BBC GG UB 720/8 double-acting electric motors producing a total of 750 PS for use while submerged. She had two shafts and two 1.23 m propellers. The boat was capable of operating at depths of up to 230 m.

The submarine had a maximum surface speed of 17.7 kn and a maximum submerged speed of 7.6 kn. When submerged, the boat could operate for 80 nmi at 4 kn; when surfaced, she could travel 8500 nmi at 10 kn. U-633 was fitted with five 53.3 cm torpedo tubes (four fitted at the bow and one at the stern), fourteen torpedoes, one 8.8 cm SK C/35 naval gun, 220 rounds, and one twin 2 cm C/30 anti-aircraft gun. The boat had a complement of between forty-four and sixty.

Service history
The boat's career began with training at 5th U-boat Flotilla on 30 July 1942, followed by active service on 1 March 1943 as part of the 9th Flotilla for the remainder of her short service. In one patrol she sank one merchant ship, for a total of.

Fate
U-633 was sunk on 8 March 1943 in the North Atlantic south-west of Iceland, in position 58.35°N, -31°W, by depth charges from the US Coast Guard cutter USCGC Spencer. 43 dead (all hands lost).

Wolfpacks
U-633 took part in two wolfpacks, namely:
 * Neuland (4 – 6 March 1943)
 * Ostmark (6 – 8 March 1943)