SM U-91

SM U-91 was one of the 329 submarines serving in the Imperial German Navy in World War I. U-91 was engaged in the naval warfare and took part in the First Battle of the Atlantic.

Design
Type U 87 submarines were preceded by the shorter Type U 81 submarines. U-91 had a displacement of 757 t when at the surface and 998 t while submerged. She had a total length of 65.80 m, a pressure hull length of 50.07 m, a beam of 6.20 m, a height of 9.35 m, and a draught of 3.88 m. The submarine was powered by two 2400 PS engines for use while surfaced, and two 1200 PS engines for use while submerged. She had two propeller shafts. She was capable of operating at depths of up to 50 m.

The submarine had a maximum surface speed of 15.6 kn and a maximum submerged speed of 8.6 kn. When submerged, she could operate for 56 nmi at 5 kn; when surfaced, she could travel 11380 nmi at 8 kn. U-91 was fitted with four 50 cm torpedo tubes (two at the bow and two at the stern), ten to twelve torpedoes, one 10.5 cm SK L/45 deck gun, and one 8.8 cm SK L/30 deck gun. She had a complement of thirty-six (thirty-two crew members and four officers).