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 on 14 May 1943 in the Atlantic Ocean, in position 60°32′N 31°05′W / 60.533°N 31.083°W, by depth charges from a US Catalina.
General characteristics
Class and 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); 1 × twin 2 cm (0.79 in) C/30 anti-aircraft gun;
Service record
Part of:	5th U-boat Flotilla; 17 September 1942 – 30 April 1943; 6th U-boat Flotilla; 1 – 14 May 1943;
Identification codes:	M 50 291
Commanders:	Oblt.z.S. Karl-Heinz Nagel; 17 September 1942 – 14 May 1943;
Operations:	1 patrol:; 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.^[2] 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).^[2]

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).^[2] 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 one twin 2 cm (0.79 in) C/30 anti-aircraft gun. The boat had a complement of between forty-four and sixty.^[2]

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^[3] 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 60°32′N 31°05′W / 60.533°N 31.083°W / 60.533; -31.083, by depth charges from a US Catalina of VP-84. All hands were lost.

References

^ Helgason, Guðmundur. "Karl-Heinz Nagel". German U-boats of WWII - uboat.net. Retrieved 21 April 2015.
^ ^a ^b ^c ^d Gröner 1991, pp. 43–46.
^ Kemp, Paul (1997). U-Boats Destroyed – German Submarine Losses in the World Wars. Arms and Armour Press. pp. 117, 118. ISBN 1-85409-321-5.

Bibliography

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. ISBN 1-55750-186-6.
Busch, Rainer; Röll, Hans-Joachim (1999). Der U-Boot-Krieg, 1939-1945: Deutsche U-Boot-Verluste von September 1939 bis Mai 1945 [German U-boat losses from September 1939 to May 1945] (in German). Vol. IV. Hamburg, Berlin, Bonn: Mittler. ISBN 3-8132-0514-2.
Gröner, Eric; Jung, Dieter; Maass, Martin (1991). German Warships 1815-1945: U-boats and Mine Warfare Vessels. Vol. 2. Translated by Thomas, Keith; Magowan, Rachel. London: Conway Maritime Press. ISBN 0-85177-593-4.
Sharpe, Peter (1998). U-Boat Fact File. Great Britain: Midland Publishing. ISBN 1-85780-072-9.

External links

Helgason, Guðmundur. "The Type VIIC boat U-640". German U-boats of WWII - uboat.net. Retrieved 21 April 2015.

[1] Helgason, Guðmundur. "Karl-Heinz Nagel". German U-boats of WWII - uboat.net. Retrieved 21 April 2015.

[FOOTNOTEGröner199143–46-2] Gröner 1991, pp. 43–46.

[3] Kemp, Paul (1997). U-Boats Destroyed – German Submarine Losses in the World Wars. Arms and Armour Press. pp. 117, 118. ISBN 1-85409-321-5.

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