German submarine U-638 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II.She was laid down on 16 October 1941 by Blohm & Voss, Hamburg as yard number 614, launched on 8 July 1942 and commissioned on 3 September 1942 under Kapitänleutnant Oskar Staudinger.
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-638 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 BBC 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-638 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.
The boat's career began with training at 5th U-boat Flotilla on 3 September 1942, followed by active service on 1 February 1943 as part of the 9th Flotilla for the remainder of her service.
In two patrols she sank one merchant ship, for a total of and one ship damaged.
U-638 took part in four wolfpacks, namely:
U-638 was sunk on 5 May 1943 in the North Atlantic in position 54.2°N -49°W, by depth charges from . She managed to send a final signal about the attack and the fact she was sinking. All hands were lost.
| Date | Ship Name | Nationality | Tonnage (GRT) | Fate[1] | |
|---|---|---|---|---|---|
| 7 March 1943 | Empire Light |  United Kingdom | 6,537 | Damaged | |
| 5 May 1943 | Dollus | United Kingdom | 5,507 | Sunk |