German submarine U-713

History
Nazi Germany
Name:	U-713
Ordered:	7 December 1940
Builder:	H. C. Stülcken Sohn, Hamburg
Laid down:	21 October 1941
Launched:	24 September 1942
Commissioned:	29 December 1942
Fate:	Sunk by British destroyer on 24 February 1944 north-west of Narvik
General characteristics
Class & type:	Type VIIC submarine
Displacement:	769 t (757 long tons) surfaced 871 t (857 long tons) submerged
Length:	67.10 m (220 ft 2 in) (o/a) 50.50 m (165 ft 8 in) (pressure hull)
Beam:	6.20 m (20 ft 4 in) (o/a) 4.70 m (15 ft 5 in) (pressure hull)
Height:	9.60 m (31 ft 6 in)
Draught:	4.74 m (15 ft 7 in)
Installed power:	2,800–3,200 PS (2,100–2,400 kW; 2,800–3,200 bhp) (diesels) 750 PS (550 kW; 740 shp) (electric)
Propulsion:	2 shafts 2 × diesel engines 2 × electric motors
Speed:	17.7 knots (32.8 km/h; 20.4 mph) surfaced 7.6 knots (14.1 km/h; 8.7 mph) submerged
Range:	8,500 nmi (15,700 km; 9,800 mi) at 10 knots (19 km/h; 12 mph) surfaced 80 nmi (150 km; 92 mi) at 4 knots (7.4 km/h; 4.6 mph) submerged
Test depth:	230 m (750 ft) Crush depth: 250–295 m (820–968 ft)
Complement:	4 officers, 40–56 enlisted
Armament:	5 × torpedo tubes (four bow, one stern) 14 × 53.3 cm (21 in) torpedoes or 26 TMA mines 1 × 8.8 cm (3.46 in) deck gun (220 rounds) various AA guns
Service record
Identification codes:	M 49 449
Commanders:	Oblt.z.S.d.R. Henri Gosejacob
Operations:	4 war patrols
Victories:	no ships sunk

German submarine U-713 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II. The submarine was laid down on 21 October 1941 at the H. C. Stülcken Sohn yard at Hamburg, launched on 24 September 1942, and commissioned on 29 December 1942 under the command of Oberleutnant zur See d.R. Henri Gosejacob.

Attached to 8th U-boat Flotilla based at Danzig, U-713 completed her training period on 30 June 1943 and was assigned to front-line service.

Design

German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-713 had a displacement of 769 tonnes (757 long tons) when at the surface and 871 tonnes (857 long tons) while submerged. She had a total length of 67.10 m (220 ft 2 in), a pressure hull length of 50.50 m (165 ft 8 in), a beam of 6.20 m (20 ft 4 in), a height of 9.60 m (31 ft 6 in), and a draught of 4.74 m (15 ft 7 in). The submarine was powered by two Germaniawerft F46 four-stroke, six-cylinder supercharged diesel engines producing a total of 2,800 to 3,200 metric horsepower (2,060 to 2,350 kW; 2,760 to 3,160 shp) for use while surfaced, two Garbe, Lahmeyer & Co. RP 137/c double-acting electric motors producing a total of 750 metric horsepower (550 kW; 740 shp) for use while submerged. She had two shafts and two 1.23 m (4 ft) propellers. The boat was capable of operating at depths of up to 230 metres (750 ft).

The submarine had a maximum surface speed of 17.7 knots (32.8 km/h; 20.4 mph) and a maximum submerged speed of 7.6 knots (14.1 km/h; 8.7 mph). When submerged, the boat could operate for 80 nautical miles (150 km; 92 mi) at 4 knots (7.4 km/h; 4.6 mph); when surfaced, she could travel 8,500 nautical miles (15,700 km; 9,800 mi) at 10 knots (19 km/h; 12 mph). U-713 was fitted with five 53.3 cm (21 in) torpedo tubes (four fitted at the bow and one at the stern), fourteen torpedoes, one 8.8 cm (3.46 in) SK C/35 naval gun, 220 rounds, and an anti-aircraft gun. The boat had a complement of between forty-four and sixty.

Service history

While operating against convoy JW 57 on 24 February 1944, U-713 was spotted by a Swordfish from HMS Chaser. The destroyer HMS Keppel was directed towards the U-boat and attacked with depth charges, sinking U-713 in position .