To make the trolling propulsion state of a hull match the user's liking more precisely, when the hull is to be brought into the trolling propulsion state, by stably driving an internal combustion engine at a target engine speed in a low speed range as a driving source for propelling the hull.

A small-sized ship 1 has an internal combustion engine 8 mounted in a hull 3, a propulsion means 9 for propelling the hull 3 by inputting a driving force from the engine 8, and a controller 37 for electronically controlling the operation of the engine 8. A portable terminal 40 is connected to the controller 37. A desired program can be input to the controller 37 via the portable terminal 40. The engine 8 is controlled according to the input program so that the target engine speed N of the engine 8 during trolling propulsion attains a desired value.