Patent ID: 8019498

Claim:
A ship-steering device which controls an operation of a clutch mechanism of a marine gear adapted to transmit rotation of a main engine to a propeller, so as to vary a rotational speed of the propeller in relation to a rotational speed of the main engine, comprising: ship-steering means which a ship operator operates for steering a ship; operational-input-value detection means for detecting an operational input value which the ship operator inputs to the ship-steering means; target propeller rotational-speed computation means for computing a target rotational speed of the propeller in relation to the rotational speed of the main engine on the basis of the detected operational input value; target slip-ratio determination means for determining a target slip ratio of the clutch mechanism of the marine gear within a predetermined range in order to rotate the propeller at the computed target rotational speed; and operation control means for controlling a quantity of operation of the clutch mechanism of the marine gear with the determined target slip ratio, wherein the target slip-ratio determination means determines the target slip ratio on the basis of a relation that, when the rotational speed of the main engine is less than an idle rotational speed, which is a rotational speed of the main engine under no load, the target slip ratio varies uniformly with a first inclination; when the rotational speed of the main engine is equal to or greater than the idle rotational speed and less than a predetermined rotational speed, the target slip ratio varies uniformly with a second inclination smaller than the first inclination; and when the rotational speed of the main engine is equal to or greater than the predetermined rotational speed, the target slip ratio becomes constant.