There followed in 1890 the boats WW1 and WW2, built to a Nordenfelt design. In 1903 the Friedrich Krupp Germaniawerft dockyard in Kiel completed the first fully functional German-built submarine, Forelle,[3] which Krupp sold to Russia during the Russo-Japanese War in April 1904.[4] The SM U-1 was a completely redesigned Karp-class submarine and only one was built. The Imperial German Navy commissioned it on 14 December 1906.[5] It had a double hull, a Körting kerosene engine, and a single torpedo tube.