German submarine U-553 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II.
Design
were preceded by the shorter Type VIIB submarines. U-553 had a displacement of when at the surface and while submerged. She had a total length of, a pressure hull length of, a beam of, a height of, and a draught of. The submarine was powered by two Germaniawerft F46 four-stroke, six-cylinder superchargeddiesel engines producing a total of for use while surfaced, two Brown, Boveri & Cie GG UB 720/8 double-acting electric motors producing a total of for use while submerged. She had two shafts and two 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-553 was fitted with five torpedo tubes, fourteen torpedoes, one SK C/35 naval gun, 220 rounds, and a C/30 anti-aircraft gun. The boat had a complement of between forty-four and sixty.
Departing St. Nazaire on 7 June, she achieved success north of the Azores, by sinking the Susan Maersk and the Ranella both on 12 June 1941.
3rd, 4th and 5th patrols
Her next three sorties met with mixed fortune; her third patrol saw no success, despite ranging far and wide over the north Atlantic. U-553s next foray saw her attack merchantmen such as the Silvercedar, and . The boat's fifth patrol took her toward the eastern Canadian/US coast where she succeeded in damaging the Diala on 15 January 1942 and sinking the Innerøy on 22 January.
6th and 7th patrols
The boat's sixth patrol took her from St. Nazaire as far north as the Faeroe Islands. It was unsuccessful. Outing number seven saw the submarine penetrate the Gulf of St. Lawrence where she sank two ships; the Leto and the Nicoya. The Mattawin was sent to the bottom of the Atlantic.
8th patrol
The boat's eighth patrol began with her departure from St. Nazaire on 19 July and to which she returned on 17 September after 61 days at sea, her longest. In that time, she damaged the Belgian Soldier off Newfoundland and attacked three other ships near Cuba. one of which, the Empire Bede, was sunk by gunfire from.
9th patrol
Her last full patrol commenced on 23 November 1942; she sank the Charles L D on 9 December 1942. She returned to France, but this time La Pallice on 18 December.
Loss
Her tenth and final sortie began with her departure from La Pallice on 16 January 1943. On the 20th, she sent a radio message: "Sehrohr unklar", and was never heard from again. She had suffered no casualties to her crew until lost with all hands. She most probably sank because of technical problems and was officially declared missing on 28 January 1943.
's novel Cryptonomicon includes a fictitious U-553 which runs aground about ten miles north of Qwghlm, a fictional pair of islands, Inner Qwghlm and Outer Qwghlm, off the northwestern coast of Great Britain.