German Type XXI submarine
Type XXI U-boat
U-boat is the anglicized version of the German word U-Boot , itself an abbreviation of Unterseeboot , and refers to military submarines operated by Germany, particularly in World War I and World War II...

, also known as "Elektroboote", were the first submarine
A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

s designed to operate primarily submerged, rather than as surface ship
Surface ship
A surface ship is any type of naval ship that is confined to the surface of the sea. The term is primarily used to mean any modern vessel type that is not a submarine; although a "surface ship" may range in size from a cutter to an aircraft carrier, the weapons and tactics have some commonality,...

s that could submerge as a means to escape detection or launch an attack.


The key improvement in the Type XXI was greatly increased battery capacity, roughly triple the Type VIIC
German Type VII submarine
Type VII U-boats were the most common type of German World War II U-boat. The Type VII was based on earlier German submarine designs going back to the World War I Type UB III, designed through the Dutch dummy company Ingenieurskantoor voor Scheepsbouw den Haag which was set up by Germany after...

. This gave these boats great underwater range, and dramatically reduced the time spent on or near the surface. They could travel submerged at about 5 kn (6.1 mph; 9.8 km/h) for two or three days before recharging batteries, which took less than five hours using the snorkel
Submarine snorkel
A submarine snorkel is a device which allows a submarine to operate submerged while still taking in air from above the surface. Navy personnel often refer to it as the snort.-History:...

. The Type XXI was also far quieter than the VIIC, making it harder to detect when submerged.
The Type XXI's streamlined and hydrodynamically clean hull design allowed high submerged speed. The ability to outrun many surface ships while submerged, combined with improved dive times (also a product of the new hull form), made it far harder to chase and destroy. It also gave the boat a 'sprint ability' when positioning itself for an attack. Older boats had to surface to sprint into position. This often revealed a boat's location, especially after aircraft became available for convoy escort. The new hull design also reduced visibility via marine or airborne radar when surfaced; whether this was a goal of the design or coincidence is still debated.

They also featured a hydraulic torpedo
The modern torpedo is a self-propelled missile weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with it or in proximity to it.The term torpedo was originally employed for...

 reloading system that allowed all six bow torpedo tubes to be reloaded faster than a Type VIIC could reload one tube. The Type XXI could fire 18 torpedoes in under 20 minutes. The class also featured a very sensitive passive sonar
Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...

 for the time.

The Type XXIs also had better facilities than previous U-boat classes, including a freezer for food.


Between 1943 and 1945, 118 boats were assembled by Blohm & Voss
Blohm + Voss
Blohm + Voss , is a German shipbuilding and engineering works. It is a subsidiary of ThyssenKrupp Marine Systems; there were plans to sell 80% of Blohm + Voss to Abu Dhabi Mar Group, but talks collapsed in July 2011.-History:It was founded on April 5, 1877, by Hermann Blohm and Ernst Voss as a...

 of Hamburg
-History:The first historic name for the city was, according to Claudius Ptolemy's reports, Treva.But the city takes its modern name, Hamburg, from the first permanent building on the site, a castle whose construction was ordered by the Emperor Charlemagne in AD 808...

, AG Weser
AG Weser
Aktien-Gesellschaft Weser was one of the great German shipbuilding companies, located at the Weser River in Bremen. Founded in 1873 it was finally closed in 1983. Altogether, AG Weser built about 1400 ships of different types, including many war ships...

 of Bremen, and F. Schichau of Danzig
Gdańsk is a Polish city on the Baltic coast, at the centre of the country's fourth-largest metropolitan area.The city lies on the southern edge of Gdańsk Bay , in a conurbation with the city of Gdynia, spa town of Sopot, and suburban communities, which together form a metropolitan area called the...

. Each hull was constructed from eight prefabricated sections with final assembly at the shipyards. This new method could have pushed construction time below six months per vessel, but in practice all the assembled U-boats were plagued with severe quality problems that required extensive post-production work to fix. One of the reasons was, as a result of Albert Speer
Albert Speer
Albert Speer, born Berthold Konrad Hermann Albert Speer, was a German architect who was, for a part of World War II, Minister of Armaments and War Production for the Third Reich. Speer was Adolf Hitler's chief architect before assuming ministerial office...

's decision, sections were made by companies having little experience in shipbuilding. As a result, of 118 Type XXIs completed, only four were fit for combat before the war ended in Europe.

It was planned that final assembly of Type XXI boats would eventually be carried out in the Valentin submarine pens
Valentin submarine pens
The Valentin submarine pens are a protective shelter built to construct German U-boats during World War II at Farge, a small port on the Weser River in Bremen. The pens were under construction from 1943 to March 1945 using forced labour, but were damaged by air-raids and unfinished by the end of...

, a massive, bomb–hardened concrete bunker built at the small port of Farge
Farge is a small port on the Weser River in the City of Bremen. The bombing of Bremen in World War II attacked Farge targets, including the oil storage and the Valentin submarine pens.-Bremen-Farge concentration camp:...

, near Bremen. Construction took place between 1943 and 1945, using around 10,000 concentration camp prisoners and prisoners of war as forced–labour. The facility was 90% completed when, in March 1945, it was badly damaged by Allied bunker buster
Bunker buster
A bunker buster is a bomb designed to penetrate hardened targets or targets buried deep underground.-Germany:Röchling shells were bunker-busting artillery shells, developed by German engineer August Cönders, based on the theory of increasing sectional density to improve penetration.They were tested...

 bombs and abandoned. A few weeks later, the area was captured by the British Army.


U-2511 and U-3008 were the only Type XXIs to go on war patrols, and neither sank any ships. U-2511 had a British cruiser in her sights on 4 May when news of the German cease-fire was received. She made a practice attack before leaving the scene undetected.

In 1957, U-2540, which had been scuttled
Scuttling is the act of deliberately sinking a ship by allowing water to flow into the hull.This can be achieved in several ways—valves or hatches can be opened to the sea, or holes may be ripped into the hull with brute force or with explosives...

 at the end of the war, was raised and refitted as research vessel
Research vessel
A research vessel is a ship designed and equipped to carry out research at sea. Research vessels carry out a number of roles. Some of these roles can be combined into a single vessel, others require a dedicated vessel...

 Wilhelm Bauer of the Bundesmarine. She was operated by both military and civilian crews in a research role until 1982. In 1984, she was opened to the public by the Deutsches Schiffahrtsmuseum
Deutsches Schiffahrtsmuseum
The Deutsches Schiffahrtsmuseum is a museum in Bremerhaven, Germany. It is part of the Gottfried Wilhelm Leibniz Scientific Community. The main museum building was opened on 5 September 1975 by then-president Walter Scheel, though scientific work already had started in 1971...

(German Maritime Museum) in Bremerhaven
Bremerhaven is a city at the seaport of the free city-state of Bremen, a state of the Federal Republic of Germany. It forms an enclave in the state of Lower Saxony and is located at the mouth of the River Weser on its eastern bank, opposite the town of Nordenham...

, Germany.


U-2518 became French submarine Roland Morillot
Roland Morillot (S613)
German submarine U-2518 was a Type XXI U-boat of the Kriegsmarine at the end of World War II, which later served in the French Navy, where she was commissioned as Roland Morillot, in honour of Roland Morillot, a French submarine officer killed in 1915.-Kriegsmarine:The submarine was laid down on 16...

. She saw active service during the Suez Crisis
Suez Crisis
The Suez Crisis, also referred to as the Tripartite Aggression, Suez War was an offensive war fought by France, the United Kingdom, and Israel against Egypt beginning on 29 October 1956. Less than a day after Israel invaded Egypt, Britain and France issued a joint ultimatum to Egypt and Israel,...

 in 1956, and remained in commission until 1967. She was scrapped in 1969.

Soviet Union

Four Type XXI boats were assigned to the Soviet Union by the Potsdam Agreement
Potsdam Agreement
The Potsdam Agreement was the Allied plan of tripartite military occupation and reconstruction of Germany—referring to the German Reich with its pre-war 1937 borders including the former eastern territories—and the entire European Theatre of War territory...

; these were U-3515, U-2529, U-3035, and U-3041, which were commissioned into the Soviet Navy
Soviet Navy
The Soviet Navy was the naval arm of the Soviet Armed Forces. Often referred to as the Red Fleet, the Soviet Navy would have played an instrumental role in a Warsaw Pact war with NATO, where it would have attempted to prevent naval convoys from bringing reinforcements across the Atlantic Ocean...

 as B-27, B-28, B-29, and B-30 (later B-100) respectively. However, Western intelligence believed the Soviets had acquired several more Type XXI boats; a review by the U.S. Joint Intelligence Committee for the Joint Chiefs of Staff in January 1948 estimated the Soviet Navy then had 15 Type XXIs operational, could complete construction of 6 more within 2 months, and could build another 39 within a year and a half from prefabricated sections, since several factories producing Type XXI components and the assembly yard at Danzig had been captured by the Soviets at the end of World War II. U 3538U 3557 (respectively TS-5TS-19 and TS-32TS-38) remained incomplete at Danzig and were scrapped or sunk in 1947. The four boats assigned by Potsdam were used in trials and tests until 1955, then scuttled or used for weapon testing between 1958-1973. The Type XXI formed the basis for the Project 614, essentially a copy of the Type XXI, and many of its characteristics were also incorporated into the Project 613
Whiskey class submarine
Whiskey-class submarines are a class of naval submarines that the Soviet Union built in the early Cold War period.-Design:...

 submarine (known in the West as the Whiskey class).

United Kingdom

The U-3017 was commissioned into the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 as HMS N41. She was used for tests until being scrapped in November 1949.

United States

The United States Navy took over the U-2513 and U-3008, operating them both in the Atlantic. In November 1946 President Harry S. Truman
Harry S. Truman
Harry S. Truman was the 33rd President of the United States . As President Franklin D. Roosevelt's third vice president and the 34th Vice President of the United States , he succeeded to the presidency on April 12, 1945, when President Roosevelt died less than three months after beginning his...

 became the first American President to travel on a submarine when he visited U-2513, the submarine dived to 440 feet (134.1 m) with the President on board. The U-2513 was sunk as a target in 1949; U-3008 was scrapped in 1956.


The only boat to survive intact is Wilhelm Bauer (ex-U-2540). The wrecks of other Type XXI boats are known to exist. In 1985, it was discovered that the partially-scrapped remains of U-2505, U-3004, and U-3506
German submarine U-3506
-See also:* List of German U-boats* List of shipwrecks in 1945...

 were still in the partially-demolished "Elbe II" U-boat bunker in Hamburg
-History:The first historic name for the city was, according to Claudius Ptolemy's reports, Treva.But the city takes its modern name, Hamburg, from the first permanent building on the site, a castle whose construction was ordered by the Emperor Charlemagne in AD 808...

. The bunker has since been filled in with gravel , although even that did not initially deter many souvenir hunters who measured the position of open hatches and dug down to them to allow the removal of artifacts. The wrecks now lie beneath a car park, making them inaccessible.

U-2513 lies in 213 feet (64.9 m) of water 70 miles (112.7 km) west of Key West
Key West
Key West is an island in the Straits of Florida on the North American continent at the southernmost tip of the Florida Keys. Key West is home to the southernmost point in the Continental United States; the island is about from Cuba....

, Florida. The boat has been visited by divers, but the depth makes this very difficult and the site is only considered suitable for advanced divers. Four other boats lie off the coast of Northern Ireland, where they were sunk in 1946 as part of Operation Deadlight
Operation Deadlight
Operation Deadlight was the code name for the scuttling of U-boats surrendered to the Allies after the defeat of Germany near the end of World War II....



The Type XXI design directly influenced advanced post-war submarines, the GUPPY
Greater Underwater Propulsion Power Program
The Greater Underwater Propulsion Power Program was initiated by the United States Navy after World War II to improve the submerged speed, maneuverability, and endurance of its submarines....

 improvements to the American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

Gato class submarine
The United States Navy Gato class submarine formed the core of the submarine service that was largely responsible for the destruction of the Japanese merchant marine and a large portion of the Imperial Japanese Navy in World War II...

, Balao
Balao class submarine
The Balao class was a successful design of United States Navy submarine used during World War II, and with 122 units built, the largest class of submarines in the United States Navy. An improvement on the earlier Gato class, the boats had slight internal differences...

, and Tench
Tench class submarine
Tench-class submarines were a type of submarine built for the United States Navy between 1944 and 1951. They were an evolutionary improvement over the Gato and Balao classes, only about 35 to 40 tons larger, but more strongly built and with a slightly improved internal layout...

 class submarines, and the Soviet
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

 submarine NATO reporting name
NATO reporting name
NATO reporting names are classified code names for military equipment of the Eastern Bloc...

Whiskey class submarine
Whiskey-class submarines are a class of naval submarines that the Soviet Union built in the early Cold War period.-Design:...

 and Zulu
Zulu class submarine
The Soviet Navy's Project 611, NATO reporting name Zulu class, were one of the first Soviet post-war attack submarines. They were roughly as capable as the American GUPPY fleet-boat conversions. They were a contemporary of the Whiskey class submarines and shared a similar sonar arrangement...


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