Marine propulsion system and marine vessel

Abstract

A marine propulsion system includes a main propulsion device operable to rotate in a right-left direction to change a direction of a thrust, an auxiliary propulsion device including an electric motor to drive an auxiliary thruster and operable to rotate in the right-left direction to change a direction of a thrust, and a controller configured or programmed to perform a drift control to move a hull under external forces including wind and water flow while maintaining an orientation of a bow of the hull at a target orientation by rotating the hull. The controller is configured or programmed to maintain the orientation of the bow at the target orientation by rotating the hull by driving the auxiliary thruster while stopping a main thruster of the main propulsion device in the drift control.

What is claimed is: 
     
         1 . A marine propulsion system comprising:
 a main propulsion device including a main thruster to generate a thrust, and operable to rotate in a right-left direction to change a direction of the thrust;   an auxiliary propulsion device including an electric motor to drive an auxiliary thruster to generate a thrust, operable to rotate in the right-left direction to change a direction of the thrust, and having a maximum output smaller than a maximum output of the main propulsion device; and   a controller configured or programmed to perform a drift control to move a hull under external forces including wind and water flow while maintaining an orientation of a bow of the hull at a target orientation by rotating the hull; wherein   the controller is configured or programmed to maintain the orientation of the bow at the target orientation by rotating the hull by driving the auxiliary thruster while stopping the main thruster in the drift control.   
     
     
         2 . The marine propulsion system according to  claim 1 , wherein 
 the main propulsion device is to be attached to a stern of the hull and is provided on a centerline of the hull in the right-left direction; and   the auxiliary propulsion device is to be attached to the stern and is provided to one side of the centerline of the hull in the right-left direction.   
     
     
         3 . The marine propulsion system according to  claim 1 , wherein the controller is configured or programmed to rotate the hull by driving the auxiliary thruster while stopping the main thruster without rotating the main propulsion device in the right-left direction in the drift control. 
     
     
         4 . The marine propulsion system according to  claim 3 , wherein the main propulsion device is operable to maintain a rudder angle of the main thruster at a rudder angle along a centerline of the hull in the right-left direction while stopping the main thruster when the hull is rotated by driving the auxiliary thruster in the drift control. 
     
     
         5 . The marine propulsion system according to  claim 1 , wherein the auxiliary propulsion device has a right-left rotatable angle range to change the direction of the thrust larger than a right-left rotatable angle range of the main propulsion device. 
     
     
         6 . The marine propulsion system according to  claim 1 , further comprising:
 a mode switching operator to receive an operation to switch between a normal drift mode in which the drift control is performed using only the external forces as a power source to move the hull directed to the target orientation while the main thruster of the main propulsion device is stopped, and a drift track mode in which the drift control is performed to move the hull toward a target point using the thrust of at least one of the main thruster or the auxiliary thruster in addition to the external forces as the power source.   
     
     
         7 . The marine propulsion system according to  claim 6 , wherein the controller is configured or programmed to start the drift track mode in either a first driving state in which the external forces and the main thruster are used as the power source to move the hull toward the target point, or a second driving state in which the external forces and the auxiliary thruster are used as the power source to move the hull toward the target point when the normal drift mode is switched to the drift track mode by the mode switching operator. 
     
     
         8 . The marine propulsion system according to  claim 7 , further comprising:
 a thrust adjustment operator to receive an operation to adjust thrust magnitudes of the main propulsion device and the auxiliary propulsion device; wherein   the controller is configured or programmed to: 
 start the drift track mode in the first driving state when the normal drift mode is switched to the drift track mode by the mode switching operator; and 
 switch the first driving state to the second driving state based on the thrust adjustment operator receiving an operation to change the thrust magnitudes to predetermined levels or less in the drift track mode. 
   
     
     
         9 . The marine propulsion system according to  claim 6 , wherein the controller is configured or programmed to automatically switch from the drift track mode to the normal drift mode when the hull reaches the target point and another target point is not specified. 
     
     
         10 . The marine propulsion system according to  claim 1 , wherein
 the main propulsion device is an engine outboard motor including an engine to drive a main propeller corresponding to the main thruster and provided on a centerline of the hull in the right-left direction; and   the auxiliary propulsion device is an electric outboard motor including the electric motor to drive an auxiliary propeller corresponding to the auxiliary thruster and provided to one side of the centerline of the hull in the right-left direction.   
     
     
         11 . A marine propulsion system comprising:
 a main propulsion device including a main thruster to generate a thrust, and operable to rotate in a right-left direction to change a direction of the thrust;   an auxiliary propulsion device including an auxiliary thruster to generate a thrust, and operable to rotate in the right-left direction to change a direction of the thrust and having a maximum output smaller than a maximum output of the main propulsion device; and   a controller configured or programmed to perform a drift control to move a hull under external forces including wind and water flow while maintaining an orientation of a bow of the hull at a target orientation by rotating the hull; wherein   the controller is configured or programmed to maintain the orientation of the bow at the target orientation by rotating the hull by driving the auxiliary thruster while stopping the main thruster in the drift control.   
     
     
         12 . A marine vessel comprising:
 a hull; and   a marine propulsion system provided on or in the hull; wherein   the marine propulsion system includes: 
 a main propulsion device including a main thruster to generate a thrust, and operable to rotate in a right-left direction to change a direction of the thrust; 
 an auxiliary propulsion device including an electric motor to drive an auxiliary thruster to generate a thrust, operable to rotate in the right-left direction to change a direction of the thrust, and having a maximum output smaller than a maximum output of the main propulsion device; and 
 a controller configured or programmed to perform a drift control to move the hull under external forces including wind and water flow while maintaining an orientation of a bow of the hull at a target orientation by rotating the hull; and 
   the controller is configured or programmed to maintain the orientation of the bow at the target orientation by rotating the hull by driving the auxiliary thruster while stopping the main thruster in the drift control.   
     
     
         13 . The marine vessel according to  claim 12 , wherein 
 the main propulsion device is attached to a stern of the hull and is provided on a centerline of the hull in the right-left direction; and   the auxiliary propulsion device is attached to the stern and is provided to one side of the centerline of the hull in the right-left direction.   
     
     
         14 . The marine vessel according to  claim 12 , wherein the controller is configured or programmed to rotate the hull by driving the auxiliary thruster while stopping the main thruster without rotating the main propulsion device in the right-left direction in the drift control. 
     
     
         15 . The marine vessel according to  claim 14 , wherein the main propulsion device is operable to maintain a rudder angle of the main thruster at a rudder angle along a centerline of the hull in the right-left direction while stopping the main thruster when the hull is rotated by driving the auxiliary thruster in the drift control. 
     
     
         16 . The marine vessel according to  claim 12 , wherein the auxiliary propulsion device has a right-left rotatable angle range to change the direction of the thrust larger than a right-left rotatable angle range of the main propulsion device. 
     
     
         17 . The marine vessel according to  claim 12 , wherein the marine propulsion system further includes a mode switching operator to receive an operation to switch between a normal drift mode in which the drift control is performed using only the external forces as a power source to move the hull directed to the target orientation while the main thruster of the main propulsion device is stopped, and a drift track mode in which the drift control is performed to move the hull toward a target point using the thrust of at least one of the main thruster or the auxiliary thruster in addition to the external forces as the power source. 
     
     
         18 . The marine vessel according to  claim 17 , wherein the controller is configured or programmed to start the drift track mode in either a first driving state in which the external forces and the main thruster are used as the power source to move the hull toward the target point, or a second driving state in which the external forces and the auxiliary thruster are used as the power source to move the hull toward the target point when the normal drift mode is switched to the drift track mode by the mode switching operator. 
     
     
         19 . The marine vessel according to  claim 18 , wherein 
 the marine propulsion system further includes a thrust adjustment operator to receive an operation to adjust thrust magnitudes of the main propulsion device and the auxiliary propulsion device; and   the controller is configured or programmed to:
 start the drift track mode in the first driving state when the normal drift mode is switched to the drift track mode by the mode switching operator; and 
 switch the first driving state to the second driving state based on the thrust adjustment operator receiving an operation to change the thrust magnitudes to predetermined levels or less in the drift track mode. 
   
     
     
         20 . The marine vessel according to  claim 17 , wherein the controller is configured or programmed to automatically switch from the drift track mode to the normal drift mode when the hull reaches the target point and another target point is not specified.