A sailboat is the original "carbon free" way of propulsion for boats and ships. No, it is not as fast as a hydrofoil, but it also won't run out of power except

A sailboat is the original "carbon free" way of propulsion for boats and ships. No, it is not as fast as a hydrofoil, but it also won't run out of power except under rare weather conditions (utterly becalmed). Not that boats don't do a lot of environmental damage in other ways. Bilge tanks, anti-fouling paint flaking off, etc.