Type XXI submarine

U-2540 in wartime configuration and exhibited at the Maritime Museum in Bremerhaven. It is the only floating example of a Type XXI U-boat.
Class overview
NameType XXI
Builders
Operators
Preceded by
Succeeded byType XXVI (none completed)
Cost5,750,000 ℛ︁ℳ︁ per boat[1]
Built1943–1945[1]
In commission1944–1982
Planned1,170[2]
Building267[2]
Completed118
Cancelled785[2]
Preserved1
General characteristics
TypeOceanic conventional Submarine
Displacement
  • 1,621 t (1,595 long tons) surfaced
  • 1,819 t (1,790 long tons) submerged[1]
Length76.70 m (251 ft 8 in)[1]
Beam8 m (26 ft 3 in)[1]
Draught6.32 m (20 ft 9 in)[1]
Propulsion
  • Geared Diesel/Geared battery-electric/CODABEL/Diesel-electric beltdrive/Low-noise electric beltdrive.
  • 2× MAN M6V40/46KBB geared supercharged 6-cylinder diesel engines, 4,000 PS (3,900 shp; 2,900 kW), driving:
  • 2× SSW geared GU365/30 double-acting electric motors, 5,000 PS (4,900 shp; 3,700 kW)[1]
  • 2 × SSW GV232/28 "creep motors", 226 PS (223 shp; 166 kW) for silent running, and to keep the boat moving while the batteries are being recharged.
  • 2 shafts
Speed
  • 15.6 knots (28.9 km/h; 18.0 mph) surfaced
  • 17.2 knots (31.9 km/h; 19.8 mph) submerged[1] [3]
  • 6.1 knots (11.3 km/h; 7.0 mph) (silent running motors)
Range
  • 15,500 nmi (28,700 km; 17,800 mi) at 10 knots (19 km/h; 12 mph) surfaced
  • 340 nmi (630 km; 390 mi) at 5 knots (9.3 km/h; 5.8 mph) submerged[1]
Test depth240 m (787 ft)[1]
Complement5 officers, 52 enlisted men[4]
Armament
ArmourBridge: 17mm

Type XXI submarines were a class of German diesel–electric Elektroboot (German: "electric boat") submarines designed during the Second World War. One hundred and eighteen were completed, with four being combat-ready. During the war only two were put into active service and went on patrols, but these were not used in combat.

They were the first submarines designed to operate primarily submerged, rather than spending most of their time as surface ships that could submerge for brief periods as a means of escaping detection. They incorporated many batteries to increase the time they could spend submerged, to as much as several days, and they only needed to surface to periscope depth for recharging via a snorkel. The design included many general improvements as well: much greater underwater speed by an improved hull design, greatly improved diving times, power-assisted torpedo reloading and greatly improved crew accommodations. However, the design was also flawed in many ways, with the submarines being mechanically unreliable[5] and, according to post-war analysis, vulnerable to combat damage. The Type XXI submarines were also rushed into production before design work was complete, and the inexperienced facilities which constructed the boats were unable to meet necessary quality standards.

After the war, several navies obtained Type XXIs and operated them for decades in various roles, while large navies introduced new submarine designs based on them. These include the Soviet Whiskey, American Tang, British Porpoise, and Swedish Hajen III classes, all based on the Type XXI design to some extent.[6]

  1. ^ a b c d e f g h i j Gröner, Jung & Maass 1991, p. 84–85.
  2. ^ a b c Gröner, Jung & Maass 1991, pp. 84–89.
  3. ^ "U-boat Archive - Design Studies - Type XXI".
  4. ^ a b Gröner, Jung & Maass 1991, p. 85.
  5. ^ Jones, Marcus O. (2014) "Innovation for Its Own Sake: The Type XXI U-boat", Naval War College Review, Vol. 67, No. 2, Article 9 https://digital-commons.usnwc.edu/nwc-review/vol67/iss2/9%7C[permanent dead link] p10 "Early Type XXI hulls suffered from defective diesel-engine superchargers, faulty hydraulic torpedo-loading systems, trouble-prone steering systems..."
  6. ^ H I Sutton (7 March 2021). "World-Submarine-Family-Tree". Covert Shores.