Type VIIA U-boats were designed in 1933-34 as the first series of a new generation of attack U-boats.
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 Germaniawerft, Kiel. Type VIIA U-boats were generally popular with their crews and much more powerful 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 88 mm fast-firing deck gun with about 220 rounds.
Ten Type VIIA boats were built between 1935 and 1937. All but two Type VIIA U-boats were sunk during World War II (U-29 and U-30, both scuttled in Kupfermühlen Bay on 4 May 1945).
The boat was powered on the surface by two MAN AG, 6 cylinder, 4-stroke M6V 40/46 diesels giving a total of 2,100 to 2,310 brake horsepower (1,600 to 1,720 kW) at 470 to 485 rpm. When submerged it was propelled by two BBC GG UB 720/8 electric motors giving a total of 750 horsepower (560 kW) at 322 rpm.