Control system for posture control tabs of marine vessel, marine vessel, and method for controlling posture control tabs of marine vessel that are capable of assisting operations of steering control

1. A control system for posture control tabs of a marine vessel, the control system comprising:

a port side posture control tab and a starboard side posture control tab respectively mounted on a port side and a starboard side of a stern of a hull to move up or down to control a posture of the hull;

a port side actuator and a starboard side actuator to respectively actuate the port side posture control tab and the starboard side posture control tab; and

a central processing unit configured or programmed to define and function as:

an instruction acquisition unit to acquire a steering instruction provided by a steering control that provides instructions to control a direction in which the hull moves;

a trim position acquisition unit to acquire a trim position of a propulsion device that generates a propulsive force to move the hull; and

a processor to, upon the instruction acquisition unit acquiring the steering instruction, execute a first control to:

determine an actual trim angle based on the trim position acquired by the trim position acquisition unit and a pitch angle of the hull;

determine a posture control tab to be actuated among the port side posture control tab and the starboard side posture control tab based on the actual trim angle and a reference angle; and

control one of the port side actuator and the starboard side actuator corresponding to the determined posture control tab so as to change a position of the determined posture control tab.

2. The control system according to claim 1 , wherein the processor:

compares the actual trim angle with the reference angle to determine an operation direction of the steering control in which an operation force necessary to operate the steering control becomes larger than a predetermined force, among a direction of right turning of the hull and a direction of left turning of the hull;

in a case in which a direction of a change in movement of the hull instructed by the steering instruction agrees with the determined operation direction, determines one of the port side posture control tab and the starboard side posture control tab, located on a same side as the determined operation direction, as a posture control tab to be actuated downward; and

controls one of the port side actuator and the starboard side actuator corresponding to the determined posture control tab so as to move the determined posture control tab downward.

3. The control system according to claim 1 , wherein the processor:

compares the actual trim angle with the reference angle to determine an operation direction of the steering control in which an operation force necessary to operate the steering control becomes larger than a predetermined force, among a direction of right turning of the hull and a direction of left turning of the hull;

in a case in which a direction of a change in movement of the hull instructed by the steering instruction does not agree with the determined operation direction and one of the port side posture control tab and the starboard side posture control tab, located on an opposite side to the direction instructed by the steering instruction, is positioned down, determines the one of the port side posture control tab and the starboard side posture control tab, located on the opposite side, as a posture control tab to be actuated upward; and

controls one of the port side actuator and the starboard side actuator corresponding to the determined posture control tab so as to move the determined posture control tab upward.

4. The control system according to claim 1 , wherein the processor determines a change amount of a position of the determined posture control tab based on the trim position, either a speed of the hull or a number of revolutions of an engine of the propulsion device, and the pitch angle of the hull.

5. The control system according to claim 1 , wherein the processor executes the first control on a condition that at least one of an operation amount from a neutral position of the steering control being larger than a predetermined amount and an operation speed of the steering control being faster than a predetermined operation speed is satisfied.

6. The control system according to claim 1 , wherein

the central processing unit is configured or programmed to define and function as a roll angle acquisition unit to acquire a roll angle of the hull;

the processor includes a correction mode to execute a second control to, upon the roll angle acquired by the roll angle acquisition unit exceeding a certain angle during turning of the hull defined by a direction of a resultant force of a centrifugal force and gravity with a direction of gravity, control the port side actuator and the starboard side actuator to actuate the port side posture control tab and the starboard side posture control tab so as to make the roll angle approach the certain angle; and

the processor executes the first control upon the instruction acquisition unit acquiring the steering instruction during execution of the second control in the correction mode.

7. The control system according to claim 6 , wherein, during execution of the second control in the correction mode, the processor controls the port side actuator and the starboard side actuator based on the acquired roll angle, either a speed of the hull or a number of revolutions of an engine of the propulsion device, and the pitch angle of the hull.

8. A marine vessel comprising:

a hull;

a steering control that provides instructions to control a direction in which the hull moves;

a propulsion device that generates a propulsive force to move the hull; and

a control system according to claim 1 .

9. A method for controlling posture control tabs of a marine vessel, the marine vessel including a steering control that provides instructions to control a direction in which a hull moves, a propulsion device that generates a propulsive force to move the hull, a port side posture control tab and a starboard side posture control tab respectively mounted on a port side and a starboard side of a stern of the hull to move up or down to control a posture of the hull, and a port side actuator and a starboard side actuator to respectively actuate the port side posture control tab and the starboard side posture control tab, the method comprising:

acquiring a steering instruction provided by the steering control;

acquiring a trim position of the propulsion device; and

upon acquiring the steering instruction, executing a first control to:

determine an actual trim angle based on the trim position and a pitch angle of the hull;

determine a posture control tab to be actuated among the port side posture control tab and the starboard side posture control tab based on the actual trim angle and a reference angle; and

control one of the port side actuator and the starboard side actuator corresponding to the determined posture control tab so as to change a position of the determined posture control tab.