Patent ID: 7892052

Claim:
A boat propulsion system comprising: a power source arranged to generate a rotational force; a propulsion unit including a propeller operated by the rotational force of the power source so to generate a propulsive force; a rotational speed detection section arranged to detect a rotational speed of the propeller; a shift mechanism disposed between the power source and the propulsion unit and arranged to change between a first shift position, neutral, and a second shift position to transmit the rotational force of the power source to the propulsion unit as a rotational force in a rotational direction opposite to that of the first shift position; an actuator arranged to drive the shift mechanism; a control lever to which an accelerator opening and a shift position are input by an operation of an operator; a shift position detection section arranged to detect the input shift position; an accelerator opening detection section arranged to detect the input accelerator opening; and a control unit arranged to enable the actuator to select the shift position on the basis of the detected shift position and to control an output of the power source on the basis of the detected accelerator opening; wherein the control unit is arranged to enable the actuator to maintain the first shift position until the rotational speed of the propeller becomes equal to or lower than a predetermined rotational speed and then to change to the second shift position when the control lever is operated such that the shift position detected by the shift position detection section is changed from the first shift position to the second shift position, and such that an absolute value of an accelerator opening varying speed obtained by differentiating the accelerator opening becomes equal to or larger than a predetermined value.