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 Sea and 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.

Background

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 Mediterranean and 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 Walter designed 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 Werft in 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 Linzner yard on 1 May 1944 and subsequently cancelled.Polmar, p. 322] In the end, circumstances meant that construction was concentrated at Germaniawerft in Kiel and Deutsche Werft in 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.

Description

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]

Construction

The first Type XXIII, "U-2321", was launched from Deutsche Werft in Hamburg on April 17, 1944. It was one of six XXIIIs that went on operational patrol around the British Isles in early 1945. Forty-eight others followed from Deutsche Werft and 13 from Germaniawerft of Kiel. "U-4712" was the last one launched, on April 19, 1945.

ervice history

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.

Losses

Eight Type XXIIIs were lost to various causes.
* "U-2323" was sunk by a naval mine on July 26, 1944.
* "U-2331" was lost in a training accident on October 10, 1944.
* "U-2338" was sunk. British Beaufighter aircraft killed 12 crewmen and sank the boat east-northeast of Fredericia on May 4, 1945, before she ever went on combat patrol.
* "U-2342" was sunk by a naval mine on 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.

Postwar

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 Kattegat in 1945) and "U-2367" (which sank near Schleimünde following 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

"U-2321•U-2322•U-2323•U-2324•U-2325•U-2326•U-2327•U-2328•U-2329•U-2330•U-2331•U-2332•U-2333•U-2334•U-2335•U-2336•U-2337•U-2338•U-2339•U-2340•U-2341•U-2342•U-2343•U-2344•U-2345•U-2346•U-2347•U-2348•U-2349•U-2350•U-2351•U-2352•U-2353•U-2354•U-2355•U-2356•U-2357•U-2358•U-2359•U-2360•U-2361•U-2362•U-2363•U-2364•U-2365•U-2366•U-2367•U-2368•U-2369•U-2371•U-4701•U-4702•U-4703•U-4704•U-4705•U-4706•U-4707•U-4709•U-4710•U-4711•U-4712"

Notes

References

*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

External links

* [http://uboat.net/types/xxiii.htm Type XXIII] at uboat.net