German submarine U-638

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.

Design
German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-638 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-638 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 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.

Wolfpacks
U-638 took part in four wolfpacks, namely:
 * Burggraf (26 – 28 February 1943)
 * Wildfang (28 February – 5 March 1943)
 * Raubgraf (7 – 15 March 1943)
 * Amsel 1 (3 – 5 May 1943)

Fate
U-638 was sunk on 5 May 1943 in the North Atlantic in position 54.2°N, -44.08333°W, by depth charges from HMS Sunflower (K41). She managed to send a final signal about the attack and the fact she was sinking. All hands were lost.