PURPOSE: To prevent the hull from tilting backward by way of separating a steersman from the circumference of a propeller at the stern side as well as to make improvements in inboard working properties by setting up a control seat at a position separating from the stern in the hull, while installing a control-operating means in the side or in the rear of this control seat.

CONSTITUTION: An outboard motor 12 being attached to the stern of a hull 11 is supported free of vertically tilting motion via a hollow tilt shaft 14, and a propulsion unit 17 is supported free of steering in both directions via a steering shaft 16. A control seat 18 is set up in a position separating from the stern in the hull 11. In brief, a seat plate 19 constituting this control seat 18 is locked to the hull 11. A navigation control 21 is set up in place from side to rear of this control seat 18. That is, a block 23 is locked to the seat plate 19 of the control seat 18 with a bolt 22, and a boss part of a steering handle 26 is rotatably supported on a stepped boltlike fulcrum shaft 24 installed in this block 23. With operation of this steering handle 26, the propulsion unit 17 is turned round via a link 31, a cable 36, a link 3, a steering lever 16A or the like.