- German Type XXIII submarine
German Type XXIII submarines were the first so-called elektroboats to become operational. They were small coastal submarines designed to operate in the shallow waters of the
North Sea, Black Seaand Mediterranean Sea, where larger Type XXI Elektro boats were at risk in World War II. They were so small they could carry only two torpedoes, which had to be loaded externally. As with their far larger brothers — the Type XXI — they were able to remain submerged almost all of the time and were faster than all previous designs worldwide, due to the improved streamlining of their shape, batteries with larger capacity and the snorkel, which allowed the diesel engines to be used while submerged. The Type XXI and XXIII U-boats revolutionized post-war submarine design.
When development began on the Type XXI U-boat in late 1942, it was proposed to simultaneously develop a smaller version incorporating the same advanced technology to replace the Type II coastal submarine. Admiral Karl Dönitz added two requirements: as the boat would have to operate in the
Mediterraneanand the Black Sea, it had to be able to be transported by rail, and it had to use the standard 21 inch torpedo tubes.
The development of the Type XXIII was given a high priority, with an emphasis on using existing components as far as possible. To reduce development time,
Hellmuth Walterdesigned the new submarine based on the previous Type XXII prototype. By 30 June 1943 the design was ready and construction began in parallel at several shipyards in Germany, France, Italy and German-occupied Russia. The lead contractor was Deutsche Werftin Hamburg.
As with the Type XXI, the Type XXIII was intended to be constructed in sections, various modules being produced by different subcontractors. Some were to be assembled at foreign yards, including "U-2446" through "U-2460" at the Deutsche Werft yard at
Mykolaiv. These were reassigned to the Linzneryard on 1 May 1944 and subsequently cancelled.Polmar, p. 322] In the end, circumstances meant that construction was concentrated at Germaniawerftin Kieland Deutsche Werftin Hamburg, Germaniawerft building 51 and Deutsche Werft 49. Of the 280 submarines ordered, only 61 entered service, and only 6 ever carried out a war patrol.
The Type XXIII had an all-welded single hull design, the first submarine to use a single hull. It had a fully streamlined outer casing and apart from the relatively small conning tower and a fairing which housed the Diesel exhaust silencer, it had an uncluttered upper deck. In line with Walter's design practice, there were no forward
hydroplanes, although these were added later.
The submarine was propelled by a single three-bladed propeller and steered by a single rudder. As with the Type XXI, the lower section of the figure-of-eight hull was used to house a large 62-cell battery.
In order to allow the boat to be transported by rail, the hull sections had to be limited in size to fit the standard
loading gauge. For transportation, the hull was broken into four sections and the bridge was removed. Due to the space restrictions, the forward bow section had to be made as short as possible, which meant that only two torpedo tubes could be fitted and no reload torpedoes could be carried. The torpedoes were loaded by ballasting the submarine down at the stern so that the bow lifted clear of the water and the torpedoes could be loaded directly into their tubes from a barge. [Williamson & Palmer, p. 37]
The Type XXIII proved to have excellent handling characteristics, and was highly maneuverable both on the surface and underwater. Its crash dive time was 9 seconds, and its maximum diving depth was convert|180|m|abbr=on. Speed submerged was convert|12.5|kn|abbr=on, while surfaced speed was convert|9|kn|abbr=on. A submerged speed of convert|10.5|kn|abbr=on could be attained while snorkeling. [Williamson, p. 63]
The first Type XXIII, "U-2321", was launched from
Deutsche Werftin Hamburgon April 17, 1944. It was one of six XXIIIs that went on operational patrol around the British Islesin early 1945. Forty-eight others followed from Deutsche Werftand 13 from Germaniawerftof Kiel. "U-4712" was the last one launched, on April 19, 1945.
The first patrol of a Type XXIII began late in the war when "U-2324" put to sea on
January 29, 1945. "U-2336" under the command of "Kapitänleutnant" Klusmeier sank the last ships lost in the war, on May 7, when he torpedoed a British and a Norwegian freighter inside the Firth of Forth.
None of the six operational Type XXIIIs — "U-2321", "U-2322", "U-2324", "U-2326", "U-2329" and "U-2336" — were sunk by the Allies but they sank or damaged five ships for a total of 14,601 tons.
Eight Type XXIIIs were lost to various causes.
* "U-2323" was sunk by a
naval mineon July 26, 1944.
* "U-2331" was lost in a training accident on
October 10, 1944.
* "U-2338" was sunk. British
Beaufighteraircraft killed 12 crewmen and sank the boat east-northeast of Fredericiaon May 4, 1945, before she ever went on combat patrol.
* "U-2342" was sunk by a
naval mineon December 26, 1944.
* "U-2344" was rammed and sunk by "U-2336" on
February 18, 1945.
* "U-2351" was paid off in April 1945 after bomb damage.
* "U-2359" was sunk by allied aircraft on
May 2, 1945.
* "U-2367" was rammed and sunk by an unidentified U-boat on
May 5, 1945.
In early May 1945, 31 XXIIIs were scuttled by their crews. Twenty surrendered to the Allies and were sunk in
Operation Deadlight. Only three — "U-2326" (later British submarine "N35"), "U-2353" (later British submarine "N37"), and "U-4706" (later Norwegian submarine "Knerten") — survived the war.
One Type XXIII was allocated to the Soviet Union under the terms of the
Potsdam Agreement, and a second unit was reportedly salvaged in 1948.
In 1956, the German Federal Navy raised two Type XXIII boats, "U-2365" (scuttled in the
Kattegatin 1945) and "U-2367" (which sank near Schleimündefollowing a collision with another U-boat), and recommissioned them as "U-Hai" (Shark) and "U-Hecht" (Pike), with pennant numbers S 170 and S 171 respectively. [Williamson, pp. 64-65] The experience gained from the two recommissioned submarines led to the construction of the Type 206 submarine, still in use today.
Boats in class
*cite book | last = Williamson | first = Gordon | authorlink = | coauthors = | title = Wolf Pack | publisher = Osprey Publishing | date = 2006 | location = | pages = p. 63 | url = | doi = | id = | isbn = 1846031419
*cite book | last = Williamson | first = Gordon | authorlink = | coauthors = Ian Palmer | title = Kriegsmarine U-boats 1939-45: Vol 2 | publisher = Osprey Publishing | date = 2002 | location = | pages = | url = | doi = | id = | isbn = 1841763640
*cite book | last = Polmar | first = Norman | authorlink = | coauthors = Jurrien Noot | title = Submarines of the Russian and Soviet Navies, 1718-1990 | publisher = Naval Institute Press | date = 1991 | location = | pages = | url = | doi = | id = | isbn = 0870215701
* [http://uboat.net/types/xxiii.htm Type XXIII] at uboat.net
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