It was an experiment in the late 50s to make a speedboat with a BMW 507 engine and design. But then the boat disappeared for decades, until a young guy heard of the boat, found and restored it.
The BMW 507 is a very rare BMW roadster, only around 250 cars have been produced in the 1950s. And this is the only BMW 507 boat with many parts from the 507 Roadster, including the engine.
The engine was BMW’s aluminum alloy OHV V8, of 3,168 cubic centimeters (193.3 cu in) displacement, with pushrod-operated overhead valves. It had two Zenith 32NDIX two-barrel carburetors, a chain-driven oil pump, high-lift cams, a different spark advance curve, polished combustion chamber surfaces, and a compression ratio of 7.8:1, yielding 150 horsepower (110 kW) DIN at 5,000 rpm.
See the video below: