System for and method of controlling watercraft

Abstract

A system for controlling a watercraft includes a bow thruster, an outboard motor being an only outboard motor attached to the watercraft, and a controller. The bow thruster includes a port oriented in an obliquely forward direction of the watercraft to jet a stream of water in the obliquely forward direction of the watercraft. The outboard motor is attached to the watercraft to be steered right and left. The controller is configured or programmed to control the outboard motor and the bow thruster to cause the watercraft to move sideways by a net force of a first thrust generated by the bow thruster and a second thrust generated by the outboard motor.

What is claimed is: 
     
         1 . A system for controlling a watercraft, the system comprising:
 a bow thruster including a port oriented in an obliquely forward direction of the watercraft;   an outboard motor steerable right and left and being an only outboard motor attached to the watercraft; and   a controller configured or programmed to control the outboard motor and the bow thruster to cause the watercraft to move sideways by a net force of a first thrust generated by the bow thruster and a second thrust generated by the outboard motor.   
     
     
         2 . The system according to  claim 1 , wherein the controller is configured or programmed to:
 determine a target moving direction of the watercraft; and   control a magnitude of the first thrust generated by the bow thruster, a magnitude of the second thrust generated by the outboard motor, and a rudder angle of the outboard motor such that the net force of the first thrust and the second thrust is oriented in the target moving direction.   
     
     
         3 . The system according to  claim 1 , wherein the outboard motor is configured to be steered within a steering range including a straight sideways direction. 
     
     
         4 . The system according to  claim 1 , wherein
 the outboard motor is switchable from a neutral state to a right steering state and a left steering state, the outboard motor being oriented in a straight rear direction of the watercraft in the neutral state, in a direction slanted rightward from the straight rear direction of the watercraft in the right steering state, and in a direction slanted leftward from the straight rear direction of the watercraft in the left steering state;   the controller is configured or programmed to:
 determine a target moving direction of the watercraft; 
 cause the bow thruster to jet a stream of water right-forward and set the outboard motor to the right steering state when the target moving direction of the watercraft is either a left direction or an obliquely left direction; and 
 cause the bow thruster to jet a stream of water left-forward and set the outboard motor to the left steering state when the target moving direction of the watercraft is either a right direction or an obliquely right direction. 
   
     
     
         5 . The system according to  claim 4 , wherein the controller is configured or programmed to:
 determine a target turning direction of the watercraft;   control the outboard motor and the bow thruster such that the net force of the first thrust generated by the bow thruster and the second thrust generated by the outboard motor extends through a position located ahead of a center of resistance of the watercraft when the target turning direction is a left turning direction; and   control the outboard motor and the bow thruster such that the net force of the first thrust generated by the bow thruster and the second thrust generated by the outboard motor extends through a position located behind the center of resistance of the watercraft when the target turning direction is a right turning direction.   
     
     
         6 . A method of controlling a watercraft including a bow thruster and an outboard motor, the bow thruster including a port oriented in an obliquely forward direction of the watercraft, and the outboard motor steerable right and left and being an only outboard motor attached to the watercraft, the method comprising:
 controlling the outboard motor and the bow thruster to cause the watercraft to move sideways by a net force of a first thrust generated by the bow thruster and a second thrust generated by the outboard motor.   
     
     
         7 . The method according to  claim 6 , wherein the outboard motor is switchable from a neutral state to a right steering state and a left steering state, the outboard motor being oriented in a straight rear direction of the watercraft in the neutral state, in a direction slanted rightward from the straight rear direction of the watercraft in the right steering state, and in a direction slanted leftward from the straight rear direction of the watercraft in the left steering state, the method further comprising:
 determining a target moving direction of the watercraft;   causing the bow thruster to jet a stream of water right-forward and setting the outboard motor to the right steering state when the target moving direction of the watercraft is either a left direction or an obliquely left direction; and   causing the bow thruster to jet a stream of water left-forward and setting the outboard motor to the left steering state when the target moving direction of the watercraft is either a right direction or an obliquely right direction.   
     
     
         8 . The method according to  claim 7 , further comprising:
 determining a target turning direction of the watercraft;   controlling the outboard motor and the bow thruster such that the net force of the first thrust generated by the bow thruster and the second thrust generated by the outboard motor extends through a position located ahead of a center of resistance of the watercraft when the target turning direction is a left turning direction; and   controlling the outboard motor and the bow thruster such that the net force of the first thrust generated by the bow thruster and the second thrust generated by the outboard motor extends through a position located behind the center of resistance of the watercraft when the target turning direction is a right turning direction.