German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-577 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 Brown, Boveri & Cie 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-577 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 a 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 7th U-boat Flotilla on 3 July 1941, followed by active service on 1 October 1941 as part of the 1st Flotilla. On 1 January 1942, she transferred to operations in the Mediterranean with 29th Flotilla, and was sunk just two weeks later.
In 3 patrols she sank no ships.
U-577 took part in three wolfpacks, namely:
U-577 was sunk on 15 January 1942 in the Mediterranean NW of Mersa Matruh, in position 32.6667°N 73°W, by depth charges from RN Swordfish from 815 Squadron. All hands were lost.