Type X submarine

U-234 surrenders to USS Sutton, 1945
Class overview
Builders	Germaniawerft, Kiel
Operators	Kriegsmarine   Imperial Japanese Navy
Preceded by	Type IX submarine
Succeeded by	Type XIV submarine (tanker submarine) Type XVII submarine (coastal submarine)
Built	1939 -1944
In commission	1941 -1945
Completed	8
Lost	6
General characteristics
Class & type	Submarine minelayer
Displacement	1,763 tonnes (1,735 long tons) surfaced 2,177 tonnes (2,143 long tons) submerged
Length	89.80 m (294 ft 7 in) o/a 70.90 m (232 ft 7 in) pressure hull
Beam	9.20 m (30 ft 2 in) o/a 4.75 m (15 ft 7 in) pressure hull
Height	10.20 m (33 ft 6 in)
Draught	4.71 m (15 ft 5 in)
Propulsion	2 × diesel engines, 4,800 PS (4,700 bhp; 3,500 kW) 2 × electric motors, 1,100 PS (1,100 shp; 810 kW)
Speed	17 knots (31 km/h; 20 mph) surfaced 7 knots (13 km/h; 8.1 mph) submerged
Range	18,450 nautical miles (34,170 km; 21,230 mi) at 10 knots (19 km/h; 12 mph) surfaced 93 nmi (172 km; 107 mi) at 4 knots (7.4 km/h; 4.6 mph) submerged
Test depth	Calculated crush depth: 220 m (720 ft)
Complement	5 officers, 47 enlisted
Armament	2 × 53.3 cm (21 in) stern torpedo tubes 15 × torpedoes 66 × SMA mines 1 × 10.5 cm (4.1 in) deck gun [1] (200 rounds)

Type X (XB) U-boats were a special type of large German submarine (U-boat). Eight were built during World War II. Although intended as long-range mine-layers, they were mainly used as supply submarines, a task they shared with the Type XIV.

Design

All U-boats of the German Kriegsmarine were potential minelayers since the Germans had devised TMB and TMC torpedo-mines which could be ejected through torpedo tubes. These torpedo-mines were ground mines which had to be laid in shallow waters of maximum 20 m (65 ft 7 in) depth. For minelaying in deeper waters a torpedo mine would not be effective since the space needed for the anchor of the mine would reduce the size of the warhead. The Germans had in mind to develop a larger SMA moored mine, to be laid through mine shafts by a large, dedicated submarine. ^[2]

Two designs were produced for a minelaying submarine: ^[3] the initial Type X design had the same layout as the world war I Type UE II, with a bow torpedo compartment and dry storage for mines in a stern compartment, which were ejected through horizontal tubes. Dry storage allowed mine detonators to be individually adjusted before launch. This submarine was projected to displace 2,284 t (2,248 long tons). A further variant, the Type XA was projected to displace up to 2,500 t (2,500 long tons), by adding lateral mine shafts in the saddle tanks for mines in wet storage. But in the end the German navy adopted a much smaller Type XB submarine, which kept the saddle mine shafts but substituted the stern dry storage mine compartment for a bow wet storage mine compartment with six vertical shafts. This allowed to install larger diesel engines for better surface speed. Instead of the four bow torpedo tubes, two stern torpedo tubes were installed. ^{[2] [4]}

On 25 September 1937, plans were approved to start building a Type XB U-boat on 1 October 1938 at the Germaniawerft in Kiel, with a building time of two years. The design of the large U-boat took more time than foreseen, and construction was delayed. In October 1938, after Hitler made clear he wanted to reject the Anglo-German Naval Agreement, the German navy initiated the Plan Z for the construction of a large German fleet. The plan Z called for the construction of nine Type XB by 1944: three to be build between April 1939 and September 1941, one between April 1941 and December 1943 and a further five between April 1942 and September 1945. The first three Type XB U-116 - U-118 were ordered in January 1939. At the outbreak of World War II, the plan Z was cancelled and various U-boat construction programmes were considered, before on 15 June a restricted Construction Programme was approved, which foresaw the delivery of four Type XBs between April 1941 and January 1942. ^[5] As Dönitz supported Type XB construction, by June 1941 four more were ordered, for delivery in 1942-43. ^[6]

The first Type XB was launched in May 1941. ^[4]

Characteristics

A Type XA U-boat had an overall length of 89.90 m (294 ft 11 in), a beam of 9.20 m (30 ft 2 in) and a draft of 4.71 m (15 ft 5 in). On the surface a Type XA displaced 1,763 t (1,735 long tons), and submerged 2,177 t (2,140 long tons). The length of the pressure hull was 70.90 m (232.6 ft) and had a maximum diameter of 4.75 m (15 ft 7 in). ^{[7] [4]}

The boat was powered on the surface by two nine-cylinder, four-stroke MAN AG F46 a 9 pu diesel engines, giving a total of 4,200 brake horsepower (3,100 kW), which gave a maximum speed of 17 knots (31 km/h; 20 mph). With a fuel capacity of 368 t (362 long tons), the range was 18,450 nmi (34,170 km; 21,230 mi) at 10 knots (19 km/h; 12 mph). When submerged it was propelled by two double-acting AEG GU 720/8-287 electric motors, giving a total of 800 kilowatts (1,100 hp). Maximum submerged speed was 7 knots (13 km/h; 8.1 mph) and maximum range was 93 nmi (172 km; 107 mi) at 4 knots (7.4 km/h; 4.6 mph). Their complement consisted of five officers and forty-seven men. ^{[8] [7] [9] [4]}

Service history

Six of the eight boats built were sunk during the war (four with all hands) but two survived World War II. One survivor was U-234, which surrendered to US Navy ships on 14 May 1945 while en route for Japan with a cargo that included 560 kg uranium oxide, two Me 262 jet fighters, and 10 jet engines.

The other type XB to survive was U-219 which reached Batavia (present-day Jakarta) in December 1944 with a cargo including dismantled V-2 rockets for Japan. Following Germany's surrender, U-219 was seized by the Japanese at Batavia on 8 May 1945 and on 15 July 1945 was placed into service with the Imperial Japanese Navy as I-505.

List of Type X submarines

There were eight Type X submarines commissioned.

	Sunk [4]	Fate [4]
U-116	6 October 1942	Disappeared in the North Atlantic and was presumed sunk
U-117	7 August 1943	Sunk in the North Atlantic by aircraft from USS Card.
U-118	12 June 1943	Sunk near the Canary Islands by aircraft from USS Bogue.
U-119	24 June 1943	Sunk in the Bay of Biscay by ramming and depth charges from HMS Starling
U-219	8 May 1945	Seized by the Japanese at Batavia. On 15 July 1945 she was placed into service with the Imperial Japanese Navy as I-505.
U-220	28 October 1943	Sunk in the North Atlantic by aircraft from USS Block Island.
U-233	5 July 1944	Sunk southeast of Halifax, Nova Scotia by destroyer escorts USS Baker and USS Thomas.
U-234	14 May 1945	Surrendered to US Navy ships

References

1. Campbell, John Naval Weapons of World War Two ISBN   0-87021-459-4 pp.248&249
2. Rössler 1981, p. 110.
3. Williamson 2005, p. 53.
4. Gröner 1991, pp. 76–77.
5. Rössler 1981, pp. 114–125.
6. Rössler 1981, pp. 127, 146.
7. Herzog 1993, p. 200.
8. Möller & Brack 2004, p. 105.
9. Bagnasco 1977, p. 74.

Bibliography

• Bagnasco, Erminio (1977). Submarines of World War Two. Annapolis: Naval Institute Press. ISBN   0870219626.
• Gröner, Erich; 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.
• Herzog, Bodo (1993). Deutsche U-Boote: 1906−1966[German U-boats: 1906−1966] (in German). Erlangen: Müller. ISBN   978-3-86070-036-5.
• Möller, Eberhard; Brack, Werner (2004). The Encyclopedia of U-Boats: from 1904 to the present. London: Chatham. ISBN   978-1-85367-623-9.
• Rössler, Eberhard (1981). The U-boat: The evolution and technical history of German submarines. London: Cassell & Co. ISBN   0-304-36120-8.
• Williamson, Gordon (2005). Wolf Pack: The Story of the U-boat in World War II. Oxford: Osprey Publishing. ISBN   1-84176-872-3.

Further reading

• Rohwer, Jürgen (2005). Chronology of the War at Sea 1939–1945: The Naval History of World War Two (Third Revised ed.). Annapolis, Maryland: Naval Institute Press. ISBN   1-59114-119-2.
• Sharpe, Peter (1998). U-Boat Fact File: Detailed Service Histories of the Submarines Operated by the Kriegsmarine 1935-1945. Leicester: Midland Publishing. ISBN   1-85780-072-9.
• Williamson, Gordon; Palmer, Ian (2002). Kriegsmarine U-boats 1939-45: Vol 2. Osprey Publishing. ISBN   1-84176-364-0.

External links

• Media related to Type X submarines at Wikimedia Commons