Patent ID: 8011984

Claim:
A boat propulsion system comprising: a power source to generate a turning force; a propeller to be rotated by the turning force of the power source; a shift position change mechanism including an input shaft to which the turning force of the power source is input, an output shaft to output the turning force to the propeller, and a clutch to engage or disengage the input shaft and the output shaft, and to change a shift position between a forward, a reverse, and a neutral position in which the clutch is disengaged; and a control device to control the shift position change mechanism; wherein the control device controls an engaging state of the clutch so that the rotational speed of the output shaft is substantially the same as the rotational speed of the input shaft in a first mode in which the shift position is the forward or the reverse, and the control device controls the engaging state of the clutch so that the rotational speed of the output shaft is lower than the rotational speed of the input shaft in a second mode in which the shift position is the forward or the reverse position.