German submarine U-871

German submarine U-871 was a long-range Type IXD2 U-boat built for Nazi Germany's Kriegsmarine during World War II.

She was ordered on 25 August 1941, and was laid down on 14 November 1942 at DeSchiMAG AG Weser, Bremen, as yard number 1079. She was launched on 7 September 1943 and commissioned under the command of Kapitänleutnant Erwin Ganzer on 15 January 1944.

Design
German Type IXD2 submarines were considerably larger than the original Type IXs. U-871 had a displacement of 1610 t when at the surface and 1799 t while submerged. The U-boat had a total length of 87.58 m, a pressure hull length of 68.50 m, a beam of 7.50 m, a height of 10.20 m, and a draught of 5.35 m. The submarine was powered by two MAN M 9 V 40/46 supercharged four-stroke, nine-cylinder diesel engines plus two MWM RS34.5S six-cylinder four-stroke diesel engines for cruising, producing a total of 9000 PS for use while surfaced, two Siemens-Schuckert 2 GU 345/34 double-acting electric motors producing a total of 1000 shp for use while submerged. She had two shafts and two 1.85 m propellers. The boat was capable of operating at depths of up to 200 m.

The submarine had a maximum surface speed of 20.8 kn and a maximum submerged speed of 6.9 kn. When submerged, the boat could operate for 121 nmi at 2 kn; when surfaced, she could travel 12750 nmi at 10 kn. U-871 was fitted with six 53.3 cm torpedo tubes (four fitted at the bow and two at the stern), 24 torpedoes, one 10.5 cm SK C/32 naval gun, 150 rounds, and a 3.7 cm with 2575 rounds as well as two 2 cm anti-aircraft guns with 8100 rounds. The boat had a complement of fifty-five.

Service history
U-871 was sunk by depth charges northwest of the Azores, by a British B-17 Flying Fortress of 220 Squadron/P RAF. All 69 of her crew were lost.

The wreck lies at 43.3°N, -36.46667°W.