Boatman
In ships or ferries, the person who steers is called a helmsman. In relatively small boats, the person that steers the boat is called a skipper.
The person who drives the taxi in Animal Crossing Wild World is Capp'n. If you ever had the Gamecube version he is the guy in the boat that takes you to Animal Crossing Island.
It could be anyone. But mainly the helmsman, but it could be the Skipper (Captain) if it's a small sport boat like a bow-rider. But normally the owner of the boat or person hired to Captain the boat drives the boat or the helmsman.
The captain
A pilot drives and maneuvers a boat depending on where it is going.
A person that drives a passenger actually drives the car for the owner. This special essential person is called a Chauffeur.
A "Pilot" is a person who drives a plane.
A boat person is a person who enjoys boating or yachting.
a person who drives a car for some body, that would be a chauffeur.
A chauffeur is a person who drives a motor car for other people.
With a rudder on shaft- driven propellers, and on stern drives and outboards the propeller is swivelled, as are jet drives. Or just with a steering wheel.