Copper holds onto heat well, which is why these tanks are a staple for older vessels. The metal construction handles the vibration and constant motion of the water much better than plastic alternatives. You can count on the tank to keep the water warm long after the engine has cooled down. Since they are built to last, they often survive for years in damp engine rooms without showing much wear. It is a straightforward way to keep hot water on tap without dealing with complex modern electronics or plastic housing.
copper marine water heater
Durable copper heaters designed for life at sea.