German Type IXD2 submarines were considerably larger than the original
Type IXs. U-871 had a displacement of 1,610 tonnes (1,580 long tons) when at the surface and 1,799 tonnes (1,771 long tons) while submerged.[4] The U-boat had a total length of 87.58 m (287 ft 4 in), a
pressure hull length of 68.50 m (224 ft 9 in), a
beam of 7.50 m (24 ft 7 in), a height of 10.20 m (33 ft 6 in), and a
draught of 5.35 m (17 ft 7 in). 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 9,000 metric horsepower (6,620 kW; 8,880 shp) for use while surfaced, two
Siemens-Schuckert 2 GU 345/34
double-acting electric motors producing a total of 1,000 shaft horsepower (1,010 PS; 750 kW) for use while submerged. She had two shafts and two 1.85 m (6 ft)
propellers. The boat was capable of operating at depths of up to 200 metres (660 ft).[4]
The submarine had a maximum surface speed of 20.8 knots (38.5 km/h; 23.9 mph) and a maximum submerged speed of 6.9 knots (12.8 km/h; 7.9 mph).[4] When submerged, the boat could operate for 121 nautical miles (224 km; 139 mi) at 2 knots (3.7 km/h; 2.3 mph); when surfaced, she could travel 12,750 nautical miles (23,610 km; 14,670 mi) at 10 knots (19 km/h; 12 mph). U-871 was fitted with six 53.3 cm (21 in)
torpedo tubes (four fitted at the bow and two at the stern), 24
torpedoes, one
10.5 cm (4.13 in) SK C/32 naval gun, 150 rounds, and a
3.7 cm (1.5 in) Flak M42 with 2575 rounds as well as two
2 cm (0.79 in) C/30 anti-aircraft guns with 8100 rounds. The boat had a
complement of fifty-five.[4]
Busch, Rainer; Röll, Hans-Joachim (1997). Der U-Boot-Krieg, 1939-1945: Der U-Boot Bau auf deutschen Werften (in German). Vol. II. Hamburg, Berlin, Bonn: Mittler.
ISBN3-8132-0509-6.
Busch, Rainer; Röll, Hans-Joachim (1999). German U-boat commanders of World War II : a biographical dictionary. Translated by Brooks, Geoffrey. London, Annapolis, Md: Greenhill Books, Naval Institute Press.
ISBN1-55750-186-6.