German submarine U-317

German submarine U-317 was a Type VIIC/41 U-boat of Nazi Germany's Kriegsmarine during World War II.

The submarine was laid down on 12 September 1942 at the Flender Werke at Lübeck, launched on 1 September 1943, and commissioned on 23 October 1943 under the command of Oberleutnant zur See Peter Rahlf.

Design
German Type VIIC/41 submarines were preceded by the heavier Type VIIC submarines. U-317 had a displacement of 759 t when at the surface and 860 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 Garbe, Lahmeyer & Co. RP 137/c 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-317 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), one 3.7 cm Flak M42 and two 2 cm C/30 anti-aircraft guns. The boat had a complement of between forty-four and sixty.

Service history
 U-317 served with the 4th U-boat Flotilla for training, and later with the 9th U-boat Flotilla in front-line service from 1 to 26 June 1944.

U-317's first patrol took her from Kiel in Germany to Egersund in Norway, between 31 May and 2 June 1944. She then sailed from Egersund on 21 June for her second and final patrol.

U-317 was sunk with all hands on 26 June 1944, northeast of the Shetland islands, in position 62.05°N, 1.75°W, by depth charges dropped by a Liberator anti-submarine bomber of No. 86 Squadron RAF.