German submarine U-170

German submarine U-170 was a Type IXC/40 U-boat of Nazi Germany's Kriegsmarine built for service during World War II. Her keel was laid down on 21 May 1941 by the Deutsche Schiff- und Maschinenbau AG in Bremen as yard number 709. She was launched on 6 June 1942 and commissioned on 19 January 1943 with Kapitänleutnant Günther Pfeffer in command.

The U-boat's service began with training as part of the 4th U-boat Flotilla. She then moved to the 10th flotilla on 1 June 1943 for operations. She was reassigned to the 33rd flotilla on 1 November 1944.

Design
German Type IXC/40 submarines were slightly larger than the original Type IXCs. U-170 had a displacement of 1144 t when at the surface and 1257 t while submerged. The U-boat had a total length of 76.76 m, a pressure hull length of 58.75 m, a beam of 6.86 m, a height of 9.60 m, and a draught of 4.67 m. The submarine was powered by two MAN M 9 V 40/46 supercharged four-stroke, nine-cylinder diesel engines producing a total of 4400 PS for use while surfaced, two Siemens-Schuckert 2 GU 345/34 double-acting electric motors producing a total of 1000 PS for use while submerged. She had two shafts and two 1.92 m propellers. The boat was capable of operating at depths of up to 230 m.

The submarine had a maximum surface speed of 18.3 kn and a maximum submerged speed of 7.3 kn. When submerged, the boat could operate for 63 nmi at 4 kn; when surfaced, she could travel 13850 nmi at 10 kn. U-170 was fitted with six 53.3 cm torpedo tubes (four fitted at the bow and two at the stern), 22 torpedoes, one 10.5 cm SK C/32 naval gun, 180 rounds, and a 3.7 cm SK C/30 as well as a 2 cm C/30 anti-aircraft gun. The boat had a complement of forty-eight.

First patrol
U-170's first patrol began with her departure from Kiel on 27 May 1943. Her route took her the long way around the British Isles to the Atlantic Ocean west of the Azores. She had passed through the 'gap' between Iceland and the Faroe Islands. She arrived at Lorient in occupied France on 9 July.

Second patrol
Her second sortie was to the Brazilian coast. Here she sank the Campos (4,663 tons) on 23 October 1943, 5 nmi south of Alcatazes Island.

Third patrol
The boat's third foray was to the US east coast. She departed Lorient on 9 February 1944 and returned to the same port on 27 May.

Fourth patrol
Her last patrol was to the waters off West Africa. On the return voyage to Germany, she was attacked by unidentified destroyers west of southern Ireland on 30 October 1944 and was badly damaged. She also reported a damaged Schnorchel (underwater breathing device), on 5 November and docked in Norway for repairs. She arrived at Flensburg on 4 December.

Fate
U-170 surrendered in Horten Naval Base, Norway on 9 May 1945, and was transferred to Loch Ryan in Scotland. She was scuttled on 30 November 1945 as part of Operation Deadlight.