FL-boat
The FL-boat (Fernlenkboot, literally "remote controlled boat") was a weapon used by the Imperial German Navy during World War I. It was a remote-controlled motorboat, 17 m long, carrying 700 kg of explosives, which was intended to be steered directly at its targets - initially the Royal Navy monitors operating off the coast of Flanders.
FL-boats were driven by internal combustion engines, and controlled remotely from a shore station through several miles of wire wound on a spool on the boat. An aircraft was used to signal directions to the shore station. They could attain speeds of 30 knots. They were constructed by Siemens-Schuckertwerke.
On 1 March 1917 an FL-boat hit the Nieuwpoort mole and on 28 October 1917 one hit the Royal Navy monitor HMS Erebus.
See also
MT explosive motorboat, similar Italian boats of WWII
References
Karau, Mark D. (2003), Wielding the Dagger: The Marinekorps Flandern and the German War, Praeger/Greenwood, p. 91, ISBN 0-313-32475-1
Lightoller, C.H. (1935), Titanic and other ships, I. Nicholson and Watson