I had a small sail boat with an electric inboard engine. The electric motor, through pulleys and a belt, turned a shaft to turn a prop. All of the machinery fro

I had a small sail boat with an electric inboard engine. The electric motor, through pulleys and a belt, turned a shaft to turn a prop. All of the machinery from the shaft to the prop would be the same whatever was used to drive the shaft. It was a joy to use. Absolutely quiet, always worked, instant power whenever wanted or needed. Basically zero motor maintenance, no pollution or oil anywhere. The shaft is effectively watertight through seals called packing glands. You get a drip but it is manageable and needed for lubrication.