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 Rendering of a Type XXIII submarine | |
| Class overview | |
|---|---|
| Builders |
|
| Operators | |
| Preceded by |
|
| Succeeded by | Type 201 coastal submarine |
| Built | 1944–1945 |
| In commission | 1944–1968 |
| Planned | 980[1] |
| Completed | 61 |
| Lost | 7 |
| General characteristics | |
| Type | Coastal submarine |
| Displacement |
|
| Length | 34.68 m (113 ft9+1⁄2 in) |
| Beam | 3.02 m (9 ft 11 in) |
| Draft | 3.66 m (12 ft 0 in) |
| Propulsion |
|
| Speed |
|
| Range |
|
| Test depth | 180 m (590 ft) |
| Complement | 14–18 |
| Armament |
|
GermanType XXIII submarines were the first so-calledelektroboote ("electric boats") to become operational. They were smallcoastal submarines designed to operate in the shallow waters of theNorth Sea,Black Sea andMediterranean Sea, where largerType XXI electric boats were at risk inWorld War II. They were so small they could carry only twotorpedoes, which had to be loaded externally. As with their far larger sisters—the Type XXI—they were able to remain submerged almost all of the time and were faster than conventional U-boats, due to the improved streamlining of their shape, batteries with larger capacity and thesnorkel, which allowed the diesel engines to be used while submerged. The Type XXI and XXIII U-boats revolutionized post-war submarine design. Nearly a thousand Type XXIII boats were projected towards the close of World War II, but most of these were either cancelled, scrapped incomplete, or only projected.[1]
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 theType II coastal submarine.Admiral Karl Dönitz added two requirements: as the boat would have to operate in theMediterranean and theBlack Sea, it had to be able to be transported by rail, and it had to use the standard 53.3 cm (21 in) torpedo tubes.
The development of the Type XXIII was given a high priority, with an emphasis on using existing components as much as possible. To reduce development time,Hellmuth Walter designed the new submarine based on the previousType XXII prototype. By 30 June 1943 the design was ready and construction began in parallel at several shipyards in Germany, France, Italy and Ukraine. The lead contractor wasDeutsche Werft inHamburg.
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, includingU-2446 throughU-2460 at the Deutsche Werft yard atNikolaev, Southern Ukraine. These were reassigned to theLinzner yard on 1 May 1944 and subsequently cancelled.[2] In the end, circumstances meant that construction was concentrated atGermaniawerft inKiel andDeutsche Werft inHamburg, 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, the first submarine to use such a design. 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 forwardhydroplanes, 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.[3]
In order to allow the boat to be transported by rail, the hull sections had to be limited in size to fit the standardloading 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.[4]The Type XXIII proved to have excellent handling characteristics, and was highly maneuverable both on the surface and underwater. Itscrash dive time was 9 seconds, and its maximum diving depth was 180 metres (98 fathoms). Submerged, its speed was12+1⁄2 kn (23 km/h), and while surfaced its speed was 9 kn (17 km/h). A submerged speed of10+1⁄2 kn (19 km/h) could be attained while snorkeling.[5]
The first forty-nine boats (U-2321 toU-2331, andU-2334 toU-2371) were ordered from Deutsche Werft, Hamburg, while two (U-2332 andU-2333) were ordered from Friedrich KruppGermaniawerft's yard at Kiel. Twenty-nine further boats (U-2372 toU-2400) were ordered from Deutsche Werft's wartime occupied yards at Toulon, but the first nine of these were scrapped incomplete on the stocks and the remainder never commenced.
Another sixty were ordered to be built by the company at other yards in occupied nations - thirty atGenoa (U-2401 toU-2430), fifteen atMonfalcone (U-2431 toU-2445) and another fifteen atNikolaev andLinz (U-2446 toU-2460), where a further forty (U-2461 toU-2500) were projected but never ordered. All of these were cancelled and never commenced.
Eight hundred additional units were intended to be built by Deutsche Werft - five hundred at Hamburg (U-4001 toU-4500), of which the first 120 were ordered and started were subsequently scrapped incomplete, with the others cancelled and never begun; and three hundred at Kiel (U-4701 toU-5000), where eleven (U-4701 toU-4712, excludeU-4708) were actually built (orders forU-4713 toU-4891 were cancelled, whileU-4892 toU-5000 were projected only).
The first Type XXIII,U-2321, was launched fromDeutsche Werft inHamburg on 17 April 1944. It was one of six XXIIIs that went on operational patrol around theBritish Isles in early 1945. Forty-eight others followed fromDeutsche Werft and fourteen fromGermaniawerft ofKiel.U-4712 was the last one launched, on 1 March 1945.
None of the six operational Type XXIIIs -U-2321,U-2322,U-2324,U-2326,U-2329 andU-2336 - were sunk by the Allies' ships but they sank four ships for a total of 7,392 gross register tons (GRT).
The first war patrol of a Type XXIII began whenU-2324 sailed from Kiel on 18 January 1945. Although she was to survive the war, she sank no enemy vessels. The first Type XXIII to achieve combat success wasU-2322, commanded byOberleutnant zur See Fridtjof Heckel. Sailing from a Norwegian base on 6 February 1945, she encountered a convoy offBerwick-upon-Tweed, and sank thecoasterEgholm on 25 February.U-2321, operating from the same base, sank the coasterGasray on 5 April 1945 offSt Abbs Head.U-2336, under the command ofKapitänleutnant Emil Klusmeier, sank the last Allied ships lost in the European war on 7 May 1945, when she torpedoed the freightersSneland I andAvondale Park off theIsle of May inside theFirth of Forth.[6]
TheSneland I and theAvondale Park were sunk around 23:03, less than an hour before the official German surrender, and theAvondale Park was the last merchant ship to be sunk by a U-boat. At the time it was felt that Kapitänleutnant Klusmeier, who was on his first patrol, had deliberately ignored Dönitz's ceasefire order; Klusmeier claimed that he had never received the order.[7]
Seven Type XXIIIs were lost to various causes.
In early May 1945, 31 XXIIIs were scuttled by their crews. 20 surrendered to the Allies and were sunk inOperation Deadlight. Only 3 –U-2326 (later British submarineN35),U-2353 (later British submarineN31, then Soviet submarineM-51), andU-4706 (later Norwegian submarineKnerter) – survived the war.
One Type XXIII was allocated to the Soviet Union under the terms of thePotsdam Agreement, and a second unit was reportedly salvaged in 1948.[2]
In 1956, theBundesmarine raised two Type XXIII boats,U-2365 (scuttled in theKattegat in 1945) andU-2367 (which sank nearSchleimünde [de] following a collision with another U-boat), and recommissioned them asU-Hai (Shark) andU-Hecht (Pike), with pennant numbers S 170 and S 171 respectively.[6]U-Hai sank in a gale off theDogger Bank in September 1966, taking 19 of her 20 crewmen with her. Her loss is the greatest maritime post-war disaster that theGerman Navy has suffered. The experience gained from the two recommissioned submarines led to the construction of theType 206 submarine, which was in use until 2011.
Although a total of 980 Type XXIII submarines were planned, many were scrapped incomplete (or indeed never ordered in many cases), only the following 61 vessels were built:
