Type VII submarine
Type VII U-boats were the most common type of German World War II U-boat. 703 boats were built by the end of the war. The lone surviving example, U-995, is on display at the Laboe Naval Memorial located in Laboe, Schleswig-Holstein, Germany.
Conception and production[edit]
The Type VII was based on earlier German submarine designs going back to the World War I Type UB III and especially the cancelled Type UG. The type UG was designed through the Dutch dummy company NV Ingenieurskantoor voor Scheepsbouw Den Haag (I.v.S) to circumvent the limitations of the Treaty of Versailles, and was built by foreign shipyards. The Finnish Vetehinen class and Spanish Type E-1 also provided some of the basis for the Type VII design. These designs led to the Type VII along with Type I, the latter being built in AG Weser shipyard in Bremen, Germany. The production of Type I was stopped after only two boats; the reasons for this are not certain. The design of the Type I was further used in the development of the Type VII and Type IX.
Type VII submarines were the most widely used U-boats of the war and were the most produced submarine class in history, with 703 built.[6] The type had several modifications. The Type VII was the most numerous U-boat type to be involved in the Battle of the Atlantic.
Types[edit]
Type VIIA[edit]
Type VIIA U-boats were designed in 1933–34 as the first series of a new generation of attack U-boats.[7] Most Type VIIA U-boats were constructed at Deschimag AG Weser in Bremen with the exception of U-33 through U-36, which were built at Friedrich Krupp Germaniawerft, Kiel. Despite the highly cramped living quarters, type VIIA U-boats were generally popular with their crews because of their fast crash dive speed, which was thought to give them more protection from enemy attacks than bigger, more sluggish types. Also, the smaller boat's lower endurance meant patrols were shorter. They were more heavily armed than the smaller Type II U-boats they replaced, with four bow and one external stern torpedo tubes. Usually carrying 11 torpedoes on board, they were very agile on the surface and mounted the 8.8 centimetres (3.5 in) quick-firing deck gun with about 220 rounds.[7]
Ten Type VIIA boats were built between 1935 and 1937. All but two Type VIIA U-boats were sunk during World War II (famous Otto Schuhart U-29 and U-30, which was the first submarine to sink a ship in World War II, both scuttled in Kupfermühlen Bay on 4 May 1945).[7]
The boat was powered on the surface by two MAN AG, 6-cylinder, 4-stroke M6V 40/46 diesel engines, giving a total of 2,100 to 2,310 brake horsepower (1,570 to 1,720 kW) at 470 to 485 rpm. When submerged it was propelled by two Brown, Boveri & Cie (BBC) GG UB 720/8 double-acting electric motors, giving a total of 750 horsepower (560 kW) at 322 rpm.[7]
Type VIIB[edit]
The VIIA had limited fuel capacity, so 24 Type VIIB boats were built between 1936 and 1940 with an additional 33 tonnes of fuel in external saddle tanks, which added another 2,500 nautical miles (4,600 km; 2,900 mi) of range at 10 knots (19 km/h; 12 mph) surfaced.[8] More powerful engines made them slightly faster than the VIIA. They had two rudders for greater agility. The torpedo armament was improved by moving the aft tube to the inside of the boat. Now an additional aft torpedo could be carried below the deck plating of the aft torpedo room (which also served as the electric motor room) and two watertight compartments under the upper deck could hold two additional torpedoes, giving them a total of 14 torpedoes. The only exception was U-83, which lacked a stern tube and carried only 12 torpedoes.[8]
Type VIIBs included many of the most famous U-boats of World War II, including U-48 (the most successful), Günther Prien's U-47, Otto Kretschmer's U-99, and Joachim Schepke's U-100.[8]
On the surface the boat was powered by two supercharged MAN, 6 cylinder 4-stroke M6V 40/46 diesels (except for U-45 to U-50, U-83, U-85, U-87, U-99, U-100, and U-102, which were powered by two supercharged Germaniawerft 6-cylinder 4-stroke F46 diesels) giving a total of 2,800–3,200 metric horsepower (2,100–2,400 kW) at 470 to 490 rpm. When submerged, the boat was powered by two AEG GU 460/8-276 (except in U-45, U-46, U-49, U-51, U-52, U-54, U-73 to U-76, U-99 and U-100, which retained the BBC motor of the VIIA) electric motors, giving a total of 750 metric horsepower (550 kW) at 295 rpm.[8]