/diy/ - Do It Yourself

I would look for a car engine that is converted for use in a boat.

Its actually only a different radiator, that uses the surrounding water instead of air to cool the engine. A water to water heat exchanger.

Dont know how much space you have, but I would consider a mercedes diesel engine.
Something without a turbo from a w123.
Zero electronics, runs for ever.
Only downsid is the iron block.