We can call them as Boat Builders.
Horologist
a plumber.
stylist
They would also call them boats.
Aircraft mechanic
A group of boats is a fleet.
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.
A boat trader would be a person that trades boats all day long. One of the other tasks a boat trader might have is to fix any boats the have been purchased that are in need of repair.
Boatwright ; one who makes boats .
A plumber, or DIY homeowner with basic skills.
You talk to him. Call him, text him, or do it in person! Just talk to to him about it.