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.

Claims

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.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is a perspective view of a watercraft including a system according to an example embodiment of the present invention.

[0010] FIG. 2 is a side view of an outboard motor.

[0011] FIG. 3 is a top view schematically showing a configuration of the watercraft.

[0012] FIG. 4 is a schematic diagram showing a configuration of the system.

[0013] FIG. 5 is a diagram showing a thrust generated by a bow thruster and a thrust generated by the outboard motor when the watercraft moves leftward.

[0014] FIG. 6 is a diagram showing a thrust generated by the bow thruster and a thrust generated by the outboard motor when the watercraft moves left-rearward.

[0015] FIG. 7 is a diagram showing a thrust generated by the bow thruster and that generated by the outboard motor when the watercraft moves left-forward.

[0016] FIG. 8 is a diagram showing a thrust generated by the bow thruster and a thrust generated by the outboard motor when the watercraft turns rightward and the outboard motor is in a right steering state.

[0017] FIG. 9 is a diagram showing a thrust generated by the bow thruster and a thrust generated by the outboard motor when the watercraft turns leftward and the outboard motor is in the right steering state.

[0018] FIG. 10 is a diagram showing a thrust generated by the bow thruster and a thrust generated by the outboard motor when the watercraft moves rightward.

[0019] FIG. 11 is a diagram showing a thrust generated by the bow thruster and a thrust generated by the outboard motor when the watercraft moves right-rearward.

[0020] FIG. 12 is a diagram showing a thrust generated by the bow thruster and a thrust generated by the outboard motor when the watercraft moves right-forward.

[0021] FIG. 13 is a diagram showing a thrust generated by the bow thruster and a thrust generated by the outboard motor when the watercraft turns rightward and the outboard motor is in a left steering state.

[0022] FIG. 14 is a diagram showing a thrust generated by the bow thruster and that generated by the outboard motor when the watercraft turns leftward and the outboard motor is in the left steering state.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0023] Example embodiments of the present invention will be hereinafter explained with reference to drawings. FIG. 1 is a perspective view of a watercraft 100 including a system according to an example embodiment of the present invention. The watercraft 100 includes an outboard motor 1 as the only outboard motor on the watercraft 100, and a bow thruster 10.

[0024] The outboard motor 1 is attached to the stern of the watercraft 100. The outboard motor 1 generates a thrust to propel the watercraft 100. FIG. 2 is a side view of the outboard motor 1. The outboard motor 1 is attached to the watercraft 100 through a bracket 11. The bracket 11 supports the outboard motor 1 such that the outboard motor 1 is rotatable about a steering shaft 12. The steering shaft 12 extends in an up-and-down direction of the outboard motor 1. The outboard motor 1 is steerable right and left within a steering range including a straight sideways direction of the watercraft 100. The outboard motor 1 is switchable from a neutral state in which a propeller 6 is oriented in a straight rear direction of the watercraft 100, to a right steering state in which the propeller 6 is oriented in a direction slanted rightward from the straight rear direction of the watercraft 100, and a left steering state in which the propeller 6 is oriented in a direction slanted leftward from the straight rear direction of the watercraft 100.

[0025] The outboard motor 1 includes an engine 2, a driveshaft 3, a propeller shaft 4, and a shift mechanism 5. The engine 2 generates the thrust to propel the watercraft 100. The engine 2 includes a crankshaft 13. The crankshaft 13 extends in the up-and-down direction of the outboard motor 1. The driveshaft 3 is connected to the crankshaft 13. The driveshaft 3 extends in the up-and-down direction of the outboard motor 1. The propeller shaft 4 extends in a front-and-back direction of the outboard motor 1. The propeller shaft 4 is connected to the driveshaft 3 through the shift mechanism 5. The propeller shaft 4 is provided with the propeller 6 attached thereto.

[0026] The shift mechanism 5 includes a forward moving gear 14, a rearward moving gear 15, and a dog clutch 16. When gear engagement of each gear 14, 15 is switched by the dog clutch 16, the direction of rotation transmitted from the drive shaft 3 to the propeller shaft 4 is switched. Movement of the watercraft 100 is thus switched between forward movement and rearward movement.

[0027] More specifically, the shift mechanism 5 is switchable among a forward moving state, a rearward moving state, and a neutral state. When the shift mechanism 5 is in the forward moving state, the dog clutch 16 is connected to the forward moving gear 14. Accordingly, the rotation of the driveshaft 3 is transmitted to the propeller shaft 4 so as to rotate the propeller shaft 4 in a forward moving direction. When the shift mechanism 5 is in the rearward moving state, the dog clutch 16 is connected to the rearward moving gear 15. Accordingly, the rotation of the driveshaft 3 is transmitted to the propeller shaft 4 so as to rotate the propeller shaft 4 in a rearward moving direction. When the shift mechanism 5 is in the neutral state, the dog clutch 16 is released from being connected to each of the forward moving gear 14 and the rearward moving gear 15. Accordingly, the rotation of the driveshaft 3 is not transmitted to the propeller shaft 4.

[0028] FIG. 3 is a top view schematically showing a configuration of the watercraft 100. As shown in FIG. 3, the bow thruster 10 is attached to the watercraft 100 to jet or eject a stream of water in an obliquely forward direction of the watercraft 100. The bow thruster 10 includes a first port 21, a second port 22, and a water stream generator 23. The first port 21 is provided in a right lateral surface of the watercraft 100. The first port 21 is oriented in a right front direction of the watercraft 100. The second port 22 is provided in a left lateral surface of the watercraft 100. The second port 22 is oriented in a left front direction of the watercraft 100. Each of the first and second ports 21 and 22 is fixed in orientation.

[0029] The water stream generator 23 generates the stream of water to be jetted from one of the first and second ports 21 and 22. The water stream generator 23 includes, for instance, a propeller and a motor. Alternatively, the water stream generator 23 may include a pump. The bow thruster 10 jets the stream of water from the first port 21 in the right front direction of the watercraft 100. The bow thruster 10 jets the stream of water from the second port 22 in the left front direction of the watercraft 100.

[0030] FIG. 4 is a schematic diagram showing a configuration of a system for controlling the watercraft 100. As shown in FIG. 4, the outboard motor 1 includes a shift actuator 7 and a steering actuator 8. The shift actuator 7 is connected to the dog clutch 16 of the shift mechanism 5. The shift actuator 7 actuates the dog clutch 16 to switch gear engagement of each gear 14, 15. Movement of the watercraft 100 is thus switched between forward movement and rearward movement. The shift actuator 7 may be, for instance, an electric motor. However, the shift actuator 7 may be another type of actuator such as an electric cylinder, a hydraulic motor, or a hydraulic cylinder.

[0031] The steering actuator 8 is connected to the outboard motor 1. The steering actuator 8 rotates the outboard motor 1 about the steering shaft 12. The outboard motor 1 is thus changed in rudder angle. The rudder angle refers to an angle of the propeller shaft 4 with respect to the front-and-back direction of the outboard motor 1. The steering actuator 8 may be, for instance, an electric motor. However, the shift actuator 7 may be another type of actuator such as an electric cylinder, a hydraulic motor, or a hydraulic cylinder.

[0032] The outboard motor 1 includes an ECU (Electric Control Unit) 9. The ECU 9 includes a processor such as a CPU (Central Processing Unit) and memories such as a RAM (Random Access Memory) and a ROM (Read-Only Memory). The ECU 9 has stored therein programs and data to control the outboard motor 1. The ECU 9 controls the engine 2.

[0033] The system includes a steering wheel 24, a remote controller 25, and a joystick 26. As shown in FIG. 1, the steering wheel 24, the remote controller 25, and the joystick 26 are disposed in a cockpit of the watercraft 100.

[0034] The steering wheel 24 allows a user to manipulate the turning direction of the watercraft 100. The steering wheel 24 includes a sensor 240. The sensor 240 outputs a steering signal indicating the operating direction and the operating amount of the steering wheel 24.

[0035] The remote controller 25 includes a throttle lever 250 and a sensor 251. The throttle lever 250 enables the user to regulate the magnitude of the thrust generated by the outboard motor 1. Additionally, the throttle lever 250 enables the user to switch the direction of the thrust generated by the outboard motor 1 between the front and rear directions. The throttle lever 250 is operable from a neutral position to a forward moving directional side and a rearward moving directional side. The neutral position is a position located between the forward moving directional side and the rearward moving directional side. The sensor 251 outputs a throttle signal indicating the operating direction and the operating amount of the throttle lever 250.

[0036] The joystick 26 is operable by the user to instruct the watercraft 100 to perform one of a plurality of moving modes. The joystick 26 is tiltable from a neutral position in at least four directions of front, rear, right, and left. Moving the watercraft 100 in four or more directions, and furthermore, all directions may be instructible by the joystick 26. The joystick 26 is rotatable about a rotational axis Ax1. In other words, the joystick 26 is operable to be twisted clockwise and counterclockwise about the rotational axis Ax1 from the middle position.

[0037] The joystick 26 includes a sensor 260. The sensor 260 outputs a joystick signal indicating how the joystick 26 has been operated. The joystick signal includes the tilt direction and the tilt amount of the joystick 26. The joystick signal includes the twist direction and the twist amount of the joystick 26 as well.

[0038] The system includes a controller 30. The controller 30 includes a processor such as a CPU and memories such as a RAM and a ROM. The controller 30 has stored programs and data therein to control the outboard motor 1 and the bow thruster 10. The controller 30 is connected to the ECU 9 and the bow thruster 10 through wired or wireless communication. The controller 30 is connected to the steering wheel 24, the remote controller 25, and the joystick 26.

[0039] The controller 30 receives the steering signal from the sensor 240. The controller 30 receives the throttle signal from the sensor 251. The controller 30 receives the joystick signal from the sensor 260. The controller 30 outputs command signals to the ECU 9 based on the signals inputted thereto from the sensors 240, 251, and 260. The command signals are transmitted to the engine 2, the shift actuator 7, and the steering actuator 8 through the ECU 9. Additionally, the controller 30 outputs a command signal to the bow thruster 10.

[0040] The controller 30 outputs a shift command for the shift actuator 7 in accordance with the operating direction of the throttle lever 250. In response, shifting between forward movement and rearward movement by the outboard motor 1 is made. The controller 30 outputs a throttle command for the engine 2 in accordance with the operating amount of the throttle lever 250. The ECU 9 controls the thrust generated by the outboard motor 1 in accordance with the throttle command. It should be noted that the throttle signal, outputted from the sensor 251, may be directly inputted to the ECU 9. The ECU 9 may output the throttle command to the engine 2 in accordance with the throttle signal inputted thereto from the sensor 251.

[0041] The controller 30 outputs a command signal for the steering actuator 8 in accordance with the operating direction and the operating amount of the steering wheel 24. When the steering wheel 24 is operated leftward from the neutral position, the controller 30 controls the steering actuator 8 such that the outboard motor 1 is in the left steering state. Accordingly, the watercraft 100 turns leftward.

[0042] When the steering wheel 24 is operated rightward from the neutral position, the controller 30 controls the steering actuator 8 such that the outboard motor 1 is in the right steering state. Accordingly, the watercraft 100 turns rightward. Additionally, the controller 30 controls the rudder angle of the outboard motor 1 in accordance with the opening amount of the steering wheel 24.

[0043] The controller 30 outputs command signals to the engine 2, the shift actuator 7, the steering actuator 8, and the bow thruster 10 in accordance with the tilt direction and the tilt amount of the joystick 26. The controller 30 controls the engine 2, the shift actuator 7, the steering actuator 8, and the bow thruster 10 such that the watercraft 100 translates at a velocity corresponding to the tilt amount of the joystick 26 in a direction corresponding to the tilt direction of the joystick 26.

[0044] When the joystick 26 is being tilted forward, the controller 30 causes the watercraft 100 to move forward by the thrust generated by the outboard motor 1 (fore surging mode). When the joystick 26 is being tilted rearward, the controller 30 causes the watercraft 100 to move rearward by the thrust generated by the outboard motor 1 (aft surging mode).

[0045] When the joystick 26 is being tilted leftward or rightward, the controller 30 causes the watercraft 100 to move leftward or rightward (swaying mode). In the swaying mode, the controller 30 controls the outboard motor 1 and the bow thruster 10 to cause the watercraft 100 to move sideways by a net force of the thrust generated by the bow thruster 10 (first thrust) and the thrust generated by the outboard motor 1 (second thrust).

[0046] For example, when the joystick 26 is being tilted leftward, the controller 30 sets the left direction as a target moving direction. When the left direction is set as the target moving direction, as shown in FIG. 5, the controller 30 causes the bow thruster 10 to jet a stream of water right-forward from the first port 21 while setting the outboard motor 1 to the right steering state. Accordingly, the controller 30 causes the bow thruster 10 to generate the first thrust (F1) oriented left-rearward while causing the outboard motor 1 to generate the second thrust (F2) oriented left-forward. The controller 30 controls the magnitude of the first thrust F1 generated by the bow thruster 10, the magnitude of the second thrust F2 generated by the outboard motor 1, and the rudder angle of the outboard motor 1 such that the net force (F3) of the first thrust F1 generated by the bow thruster 10 and the second thrust F2 generated by the outboard motor 1 is oriented in the left direction of the watercraft 100. Accordingly, the watercraft 100 translates straight leftward.

[0047] When the joystick 26 is being tilted left-rearward, the controller 30 sets the left rear direction as the target moving direction. When the left rear direction is set as the target moving direction, as shown in FIG. 6, the controller 30 causes the bow thruster 10 to jet a stream of water right-forward from the first port 21 while setting the outboard motor 1 to the right steering state. Accordingly, the controller 30 causes the bow thruster 10 to generate the first thrust F1 oriented left-rearward while causing the outboard motor 1 to generate the second thrust F2 oriented left-forward. The controller 30 controls the magnitude of the first thrust F1 generated by the bow thruster 10, the magnitude of the second thrust F2 generated by the outboard motor 1, and the rudder angle of the outboard motor 1 such that the net force F3 of the first thrust F1 generated by the bow thruster 10 and the second thrust F2 generated by the outboard motor 1 is oriented in the left rear direction of the watercraft 100. Accordingly, the watercraft 100 translates left-rearward.

[0048] When the joystick 26 is being tilted left-forward, the controller 30 sets the left front direction as the target moving direction. When the left front direction is set as the target moving direction, as shown in FIG. 7, the controller 30 causes the bow thruster 10 to jet a stream of water right-forward from the first port 21 while setting the outboard motor 1 to the right steering state. Accordingly, the controller 30 causes the bow thruster 10 to generate the first thrust F1 oriented left-rearward while causing the outboard motor 1 to generate the second thrust F2 oriented left-forward. The controller 30 controls the magnitude of the first thrust F1 generated by the bow thruster 10, the magnitude of the second thrust F2 generated by the outboard motor 1, and the rudder angle of the outboard motor 1 such that the net force F3 of the first thrust F1 generated by the bow thruster 10 and the second thrust F2 generated by the outboard motor 1 is oriented in the left front direction of the watercraft 100. Accordingly, the watercraft 100 translates left-forward.

[0049] The controller 30 controls the engine 2, the shift actuator 7, the steering actuator 8, and the bow thruster 10 such that the watercraft 100 turns at a velocity corresponding to the twisted amount of the joystick 26 in a direction corresponding to the twisted direction of the joystick 26 (turning mode).

[0050] For example, when the joystick 26 is twisted clockwise, and tilted leftward, the controller 30 sets the right turning direction as a target turning direction. When the right turning direction is set as the target turning direction while the outboard motor 1 is in the right steering state, the controller 30 causes the bow thruster 10 to jet a stream of water right-forward from the first port 21 while keeping the outboard motor 1 in the right steering state. As shown in FIG. 8, the controller 30 controls the magnitude of the first thrust F1 generated by the bow thruster 10, the magnitude of the second thrust F2 generated by the outboard motor 1, and the rudder angle of the outboard motor 1 such that the net force F3 of the first thrust F1 generated by the bow thruster 10 and the second thrust F2 generated by the outboard motor 1 extends through a position located behind the center of resistance (center of gravity) G1 of the watercraft 100. Accordingly, the watercraft 100 turns rightward.

[0051] When the joystick 26 is twisted counterclockwise, and tilted leftward, the controller 30 sets the left turning direction as the target turning direction. When the left turning direction is set as the target turning direction while the outboard motor 1 is in the right steering state, the controller 30 causes the bow thruster 10 to jet a stream of water right-forward from the first port 21 while keeping the outboard motor 1 in the right steering state. As shown in FIG. 9, the controller 30 controls the magnitude of the first thrust F1 generated by the bow thruster 10, the magnitude of the second thrust F2 generated by the outboard motor 1, and the rudder angle of the outboard motor 1 such that the net force F3 of the first thrust F1 generated by the bow thruster 10 and the second thrust F2 generated by the outboard motor 1 extends through a position located ahead of the center of resistance G1 of the watercraft 100. Accordingly, the watercraft 100 turns leftward.

[0052] When the joystick 26 is being tilted rightward, the controller 30 sets the right direction as the target moving direction. When the right direction is set as the target moving direction, as shown in FIG. 10, the controller 30 causes the bow thruster 10 to jet a stream of water left-forward from the second port 22 while setting the outboard motor 1 to the left steering state. Accordingly, the controller 30 causes the bow thruster 10 to generate the first thrust F1 oriented right-rearward while causing the outboard motor 1 to generate the second thrust F2 oriented right-forward. The controller 30 controls the magnitude of the first thrust F1 generated by the bow thruster 10, the magnitude of the second thrust F2 generated by the outboard motor 1, and the rudder angle of the outboard motor 1 such that the net force F3 of the first thrust F1 generated by the bow thruster 10 and the second thrust F2 generated by the outboard motor 1 is oriented in the right direction of the watercraft 100. Accordingly, the watercraft 100 translates straight rightward.

[0053] When the joystick 26 is being tilted right-rearward, the controller 30 sets the right rear direction as the target moving direction. When the right rear direction is set as the target moving direction, as shown in FIG. 11, the controller 30 causes the bow thruster 10 to jet a stream of water left-forward from the second port 22 while setting the outboard motor 1 to the left steering state. Accordingly, the controller 30 causes the bow thruster 10 to generate the first thrust F1 oriented right-rearward while causing the outboard motor 1 to generate the second thrust F2 oriented right-forward. The controller 30 controls the magnitude of the first thrust F1 generated by the bow thruster 10, the magnitude of the second thrust F2 generated by the outboard motor 1, and the rudder angle of the outboard motor 1 such that the net force F3 of the first thrust F1 generated by the bow thruster 10 and the second thrust F2 generated by the outboard motor 1 is oriented in the right rear direction of the watercraft 100. Accordingly, the watercraft 100 translates right-rearward.

[0054] When the joystick 26 is being tilted right-forward, the controller 30 sets the right front direction as the target moving direction. When the right front direction is set as the target moving direction, as shown in FIG. 12, the controller 30 causes the bow thruster 10 to jet a stream of water left-forward from the second port 22 while setting the outboard motor 1 to the left steering state. Accordingly, the controller 30 causes the bow thruster 10 to generate the first thrust F1 oriented right-rearward while causing the outboard motor 1 to generate the second thrust F2 oriented right-forward. The controller 30 controls the magnitude of the first thrust F1 generated by the bow thruster 10, the magnitude of the second thrust F2 generated by the outboard motor 1, and the rudder angle of the outboard motor 1 such that the net force F3 of the first thrust F1 generated by the bow thruster 10 and the second thrust F2 generated by the outboard motor 1 is oriented in the right front direction of the watercraft 100. Accordingly, the watercraft 100 translates right-forward.

[0055] When the joystick 26 is twisted clockwise, and tilted rightward while the outboard motor 1 is in the right steering state, as shown in FIG. 13, the controller 30 causes the bow thruster 10 to jet a stream of water left-forward from the second port 22 while keeping the outboard motor 1 in the left steering state. The controller 30 controls the magnitude of the first thrust F1 generated by the bow thruster 10, the magnitude of the second thrust F2 generated by the outboard motor 1, and the rudder angle of the outboard motor 1 such that the net force F3 of the first thrust F1 generated by the bow thruster 10 and the second thrust F2 generated by the outboard motor 1 extends through a position located ahead of the center of resistance G1 of the watercraft 100. Accordingly, the watercraft 100 turns rightward.

[0056] When the joystick 26 is twisted counterclockwise, and tilted rightward while the outboard motor 1 is in the left steering state, as shown in FIG. 14, the controller 30 causes the bow thruster 10 to jet a stream of water left-forward from the second port 22 while keeping the outboard motor 1 in the left steering state. The controller 30 controls the magnitude of the first thrust F1 generated by the bow thruster 10, the magnitude of the second thrust F2 generated by the outboard motor 1, and the rudder angle of the outboard motor 1 such that the net force F3 of the first thrust F1 generated by the bow thruster 10 and the second thrust F2 generated by the outboard motor 1 extends through a position located behind the center of resistance G1 of the watercraft 100. Accordingly, the watercraft 100 turns leftward.

[0057] In the system for controlling the watercraft 100 according to an example embodiment, the outboard motor 1 and the bow thruster 10 are controlled to cause the watercraft 100 to move sideways by the net force F3 of the first thrust F1 generated by the bow thruster 10 and the second thrust F2 generated by the outboard motor 1. Accordingly, the watercraft 100 is able to move sideways by only one outboard motor 1 on the watercraft 100.

[0058] Additionally, when the watercraft user slightly adjusts the movement of the watercraft 100 by oblique movement, turning, or so forth while causing the watercraft 100 to move sideways by the joystick 26, the outboard motor 1 is kept approximately constant in orientation. Thus, smooth transition is enabled between the plurality of moving modes. For example, during the leftward movement of the watercraft 100, when the watercraft user slightly adjusts the movement of the watercraft 100 by obliquely leftward movement or leftward turning while tilting the joystick 26 leftward, the outboard motor 1 is in the right steering state all the while. On the other hand, during the rightward movement of the watercraft 100, when the watercraft user slightly adjusts the movement of the watercraft 100 by obliquely rightward movement or rightward turning while tilting the joystick 26 rightward, the outboard motor 1 is in the left steering state all the while. Because of this, the outboard motor 1 is not changed much in rudder angle in transition between the moving modes. Thus, smooth transition is enabled between the plurality of moving modes.

[0059] Example embodiments of the present invention have been explained above. However, the present invention is not limited to the example embodiments described above and a variety of changes can be made without departing from the gist of the present invention.

[0060] The outboard motor 1 is not limited in configuration to the example embodiments described above and may be changed. For example, the outboard motor 1 may include an electric motor instead of the engine 2. In the example embodiments described above, the joystick 26 has been exemplified as an operating device to instruct one of the plurality of moving modes. However, the operating device is not limited to the joystick 26 and may be changed. For example, the operating device may be another type of device such as a switch or a touch screen. The moving modes may be changed from one to another, not by a manual operation performed on the operating device by the watercraft user, but by an automated watercraft operation performed by the controller 30.

[0061] While example embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.