German submarine U-640

History
Nazi Germany
Name:	U-640
Ordered:	20 January 1941
Builder:	Blohm & Voss, Hamburg
Yard number:	616
Laid down:	30 October 1941
Launched:	23 July 1942
Commissioned:	17 September 1942
Fate:	Sunk 14 May 1943 in the Atlantic Ocean, in position , by depth charges from a US Catalina.
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 (4 bow, 1 stern) 14 × torpedoes or 26 TMA mines 1 × 8.8 cm (3.46 in) deck gun (220 rounds) Various AA guns
Service record
Part of:	5th U-boat Flotilla 17 September 1942 – 30 April 1943 - Training 6th U-boat Flotilla 1–14 May 1943
Commanders:	Oblt.z.S. Karl-Heinz Nagel 17 September 1942 - 14 May 1943
Operations:	1–14 May 1943
Victories:	None

German submarine U-640 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II. She was laid down on 30 October 1941 by Blohm & Voss, Hamburg as yard number 616, launched on 23 July 1942 and commissioned on 17 September 1942 under Oberleutnant zur See Karl-Heinz Nagel.

Design

German Type VIIC submarines were preceded by the shorter Type VIIB submarines. U-640 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 Brown, Boveri & Cie GG UB 720/8 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-640 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

The boat's career began with training at 5th U-boat Flotilla on 17 September 1942, followed by active service on 1 May 1943 as part of the 6th Flotilla.

In 1 patrol she sank no ships.

Wolfpacks

U-640 took part in one wolfpack, namely

• Iller (12–14 May 1943)

Fate

There are discrepancies between the fate of U-640 and U-657, which was sunk in the same vicinity around the same time. Paul Kemp’s book attributes the sinking of British freighter Aymeric to U-640, and then subsequently sunk by HMS Swale on the 17 May 1943, whereas UBoat.net attributes this success and fate to U-657.

Uboat.net states that U-640 was sunk on 14 May 1943 in the Atlantic Ocean in position , by depth charges from a US Catalina of VP-84 Squadron. All hands were lost.