Marine propulsion system enabling movement of marine vessel in lateral direction, and control method thereof

Abstract

A marine propulsion system includes first propulsion devices located at a stern of the hull, a second propulsion device located toward a bow of the hull, and a controller. To move the hull laterally, the controller is configured or programmed to steer the first propulsion device on a port side of the hull in a leftward turning direction, and fully steer the first propulsion device on a starboard side of the hull in a rightward turning direction; cause one of the first propulsion devices to generate a forward/rearward thrust and cause another one of the first propulsion devices to generate a rearward/forward thrust to position a point of action of a resultant force of the generated thrusts in front of a turning center of the hull; and generate with the second propulsion device a counter moment to cancel a yaw moment about the turning center generated by the resultant force.

What is claimed is: 
     
         1 . A marine propulsion system comprising:
 a plurality of first propulsion devices located at a stern of a hull, and including at least a first propulsion device on a port side of the hull with respect to a center line extending in a front-rear direction of the hull, and a first propulsion device on a starboard side of the hull with respect to the center line; and   a second propulsion device located toward a bow of the hull;   a controller configured or programmed, when moving the hull in a lateral direction, to:
 fully steer in a leftward turning direction the first propulsion device on the port side of the hull, and fully steer in a rightward turning direction the first propulsion device on the starboard side of the hull so that the first propulsion device on the port side and the first propulsion device on the starboard side form an inverted V shape in a plan view; 
 cause the first propulsion device on the port side to generate a forward thrust or a rearward thrust and cause the first propulsion device on the starboard side to generate a thrust in a direction opposite to the thrust generated by the first propulsion device on the port side so that a point of action of a lateral movement force that is a resultant force of the thrust generated by the first propulsion device on the port side and the thrust generated by the first propulsion device on the starboard side is located in front of a turning center of the hull; and 
 control the second propulsion device to generate another thrust to generate a counter yaw moment to cancel a yaw moment about the turning center generated by the lateral movement force. 
   
     
     
         2 . The marine propulsion system according to  claim 1 , wherein the controller is further configured or programmed to:
 steer the first propulsion device on the port side in the rightward turning direction and steer the first propulsion device on the starboard side in the leftward turning direction so that the first propulsion device on the port side and the first propulsion device on the starboard side form a V shape in the plan view;   cause the first propulsion device on the port side to generate the forward thrust or the rearward thrust and cause the first propulsion device on the starboard side to generate a thrust in a direction opposite to the thrust generated by the first propulsion device on the port side so that a point of action of a lateral movement force that is a resultant force of the thrust generated by the first propulsion device on the port side and the thrust generated by the first propulsion device on the starboard side is located behind the turning center; and   cause the second propulsion device to generate the another thrust in a same direction as the resultant force.   
     
     
         3 . The marine propulsion system according to  claim 2 , wherein, even when the first propulsion device on the port side is steered in the rightward turning direction and the first propulsion device on the starboard side is steered in the leftward turning direction, the first propulsion device on the port side and the first propulsion device on the starboard side do not interfere with each other. 
     
     
         4 . The marine propulsion system according to  claim 2 , wherein the second propulsion device generates the another thrust in front of the bow of the hull in the same direction as the resultant force. 
     
     
         5 . The marine propulsion system according to  claim 4 , wherein
 the second propulsion device includes an extendable arm and a propeller to generate the another thrust; and   the extendable arm is extended to locate the propeller in front of the bow of the hull.   
     
     
         6 . The marine propulsion system according to  claim 4 , wherein
 the second propulsion device includes an extendable rod and a propeller to generate the another thrust; and   the propeller is located at a distal end of the extendable rod, and the extendable rod is inclined with respect to a water surface to submerge the propeller in front of the bow of the hull.   
     
     
         7 . The marine propulsion system according to  claim 2 , wherein
 to move the hull in the lateral direction to the starboard side, the controller is configured or programmed to cause the first propulsion device on the port side to generate the rearward thrust, cause the first propulsion device on the starboard side to generate the forward thrust, and cause the second propulsion device to generate the another thrust toward the starboard side; and   to move the hull in the lateral direction to the port side, the controller is configured or programmed to cause the first propulsion device on the port side to generate the forward thrust, cause the first propulsion device on the starboard side to generate the rearward thrust, and cause the second propulsion device to generate the another thrust toward the port side.   
     
     
         8 . The marine propulsion system according to  claim 1 , wherein the controller is configured or programmed to:
 steer the first propulsion device on the port side in the leftward turning direction and steer the first propulsion device on the starboard side in the rightward turning direction so that the first propulsion device on the port side and the first propulsion device on the starboard side form the inverted V shape in the plan view;   cause the first propulsion device on the port side to generate the forward thrust or the rearward thrust and cause the first propulsion device on the starboard side to generate a thrust in a direction opposite to the thrust generated by the first propulsion device on the port side so that a point of action of a lateral movement force that is a resultant force of the thrust generated by the first propulsion device on the port side and the thrust generated by the first propulsion device on the starboard side is located in front of the turning center of the hull; and   cause the second propulsion device to generate the another thrust in a direction opposite to the resultant force.   
     
     
         9 . The marine propulsion system according to  claim 8 , wherein a magnitude of the another thrust in the direction opposite to the resultant force is smaller than a magnitude of the resultant force. 
     
     
         10 . The marine propulsion system according to  claim 8 , wherein the second propulsion device generates the another thrust in front of the bow of the hull in the direction opposite to the resultant force. 
     
     
         11 . The marine propulsion system according to  claim 10 , wherein the second propulsion device includes an extendable arm and a propeller to generate the another thrust; and
 the extendable arm is extended to locate the propeller in front of the bow of the hull.   
     
     
         12 . The marine propulsion system according to  claim 10 , wherein
 the second propulsion device includes an extendable rod and a propeller to generate the another thrust; and   the propeller is located at a distal end of the extendable rod, and the extendable rod is inclined with respect to a water surface to submerge the propeller in front of the bow of the hull.   
     
     
         13 . The marine propulsion system according to  claim 8 , wherein
 to move the hull in the lateral direction to the starboard side, the controller is configured or programmed to cause the first propulsion device on the port side to generate the forward thrust, cause the first propulsion device on the starboard side to generate the rearward thrust, and cause the second propulsion device to generate the another thrust toward the port side; and   to move the hull in the lateral direction to the port side, the controller is configured or programmed to cause the first propulsion device on the port side to generate the rearward thrust, cause the first propulsion device on the starboard side to generate the forward thrust, and cause the second propulsion device to generate the another thrust toward the starboard side.   
     
     
         14 . A control method of a marine propulsion system including a plurality of first propulsion devices located at a stern of a hull and including at least a first propulsion device on a port side of the hull with respect to a center line extending in a front-rear direction of the hull and a first propulsion device on a starboard side of the hull with respect to the center line, and a second propulsion device located toward a bow of the hull, the control method comprising:
 when moving the hull in a lateral direction:
 fully steering in a leftward turning direction the first propulsion device located on the port side of the hull, and fully steering in a rightward turning direction the first propulsion device located on the starboard side of the hull so that the first propulsion device on the port side and the first propulsion device on the starboard side form an inverted V shape in a plan view; 
 causing the first propulsion device on the port side to generate a forward thrust or a rearward thrust and causing the first propulsion device on the starboard side to generate a thrust in a direction opposite to the thrust generated by the first propulsion device on the port side so that a point of action of a lateral movement force that is a resultant force of the thrust generated by the first propulsion device on the port side and the thrust generated by the first propulsion device on the starboard side is located in front of a turning center of the hull; and 
 controlling the second propulsion device to generate another thrust to generate a counter yaw moment to cancel a yaw moment about the turning center generated by the lateral movement force. 
   
     
     
         15 . A marine vessel comprising:
 a marine propulsion system including:
 a plurality of first propulsion devices located at a stern of a hull, and including at least a first propulsion device on a port side of the hull with respect to a center line extending in a front-rear direction of the hull, and a first propulsion device on a starboard side of the hull with respect to the center line; 
 a second propulsion device located toward a bow of the hull; and 
 a controller configured or programmed, when moving the hull in a lateral direction, to:
 fully steer in a leftward turning direction the first propulsion device located on the port side of the hull, and fully steer in a rightward turning direction the first propulsion device located on the starboard side of the hull so that the first propulsion device on the port side and the first propulsion device on the starboard side form an inverted V shape in a plan view; 
 cause the first propulsion device on the port side to generate a forward thrust or a rearward thrust and cause the first propulsion device on the starboard side to generate a thrust in a direction opposite to the thrust generated by the first propulsion device on the port side so that a point of action of a lateral movement force that is a resultant force of the thrust generated by the first propulsion device on the port side and the thrust generated by the first propulsion device on the starboard side is located in front of a turning center of the hull; and 
 control the second propulsion device to generate another thrust to generate a counter yaw moment to cancel a yaw moment about the turning center generated by the lateral movement force.