German submarine U-718

History
Nazi Germany
Name:	U-718
Ordered:	10 April 1941
Builder:	HC Stülcken & Sohn, Hamburg
Laid down:	18 May 1942
Launched:	26 March 1943
Commissioned:	25 June 1943
Fate:	Accidentally rammed and sunk by U-476, 18 November 1943
General characteristics
Class & type:	Type VIIC submarine
Displacement:	769 tonnes (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
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 × 53.3 cm (21 in) torpedo tubes (four bow, one stern) 14 × torpedoes 1 × 8.8 cm (3.46 in) deck gun (220 rounds) various AA guns
Service record
Part of:	Kriegsmarine: 5th U-Boat Flotilla
Commanders:	Oblt.z.S. Helmut Wieduwilt 25 June – 18 November 1943
Operations:	None
Victories:	None

German submarine U-718 was a short-lived Type VIIC U-boat built by Nazi Germany's Kriegsmarine for service during World War II. U-718 was the victim of a tragic accident during training exercises five months after completion, and thus never saw active service in the Kriegsmarine. Built at Hamburg during 1942 and 1943 and taking a year to complete, U-718 was a Type VIIC submarine and was intended for service in the Battle of the Atlantic.

Design

German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-718 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 AEG GU 460/8–27 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-718 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

On the 18 November 1943, U-718 was conducting training as part of a "wolfpack" near Bornholm in the Baltic Sea under Oberleutnant zur See Helmut Wieduwilt, when she was accidentally rammed by U-476. The submarines had been maneuvering to attack the same target in the dark, and U-476 ran aboard U-718 whilst the submarines were running on the surface. U-718's hatch was closed to prevent water entering the hull, and thus only the seven personnel in the conning tower, including Kapitänleutnant Wieduwilt, survived. The boat's hull was ruptured by the force of the impact, causing the submarine to fill and sink very rapidly, taking 43 sailors to the bottom with her. The survivors were rescued from the water by other German naval units and transferred to other boats.