System for propelling watercraft, watercraft, and method of propelling watercraft

Abstract

A watercraft propulsion system includes a primary propulsion device, an auxiliary propulsion device, a tilt cylinder, a keeping mode setting button, and a main controller. The primary and auxiliary propulsion devices are attached to a hull of a watercraft, and the auxiliary propulsion device includes an electric motor as a power source. The tilt cylinder changes a tilt angle of the auxiliary propulsion device with respect to the hull. The keeping mode setting button issues a command to execute a keeping mode to keep the hull either at a predetermined target position or oriented in a predetermined target compass direction. When the command to execute the keeping mode is issued by the keeping mode setting button, the main controller is configured or programmed to execute the keeping mode by setting either the predetermined target position or the predetermined target compass direction based on the tilt angle of the auxiliary propulsion device.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority to Japanese Patent Application No. 2024-201107 filed on Nov. 18, 2024. The entire contents of this application are hereby incorporated herein by reference.BACKGROUND OF THE INVENTION1. Field of the Invention

[0002] The present invention relates to systems for propelling watercraft, watercraft, and methods of propelling watercraft.2. Description of the Related Art

[0003] There has been disclosed a configuration that a watercraft includes a plurality of propulsion devices (see, e.g., Japan laid-open Patent Application publication No. 2024-060160). In Japan Laid-open Patent Application Publication No. 2024-060160, a primary propulsion device with a large output and an auxiliary propulsion device with a small output are installed on a hull of the watercraft. An engine propulsion device is used as the primary propulsion device, whereas an electric propulsion device is used as the auxiliary propulsion device. For example, the primary propulsion device is used in high-speed cruising toward a destination, whereas the auxiliary propulsion device is used in the vicinity of the destination so as to minutely adjust the position and the compass direction of the hull.

[0004] Moreover, in some cases, the watercraft is provided with a fixed spot keeping function to be used for such a situation as fishing. In the fixed spot keeping function, the watercraft is kept at a predetermined target position.

[0005] As described above, the primary propulsion device is used in high-speed cruising toward the destination, however, the auxiliary propulsion device is tilted up so as not to act as a resistance against the cruising. Because of this, after the watercraft reaches the target position, when a keeping control to keep the position or the compass direction of the watercraft is executed, while the auxiliary propulsion device is tilted up, chances are that the watercraft is separated from the target position by a large extent or is displaced from a target compass direction by a large extent due to external factors until the auxiliary propulsion device is tilted down and then starts operating. This results in a drawback that the keeping function cannot be executed or that the watercraft continues to move toward the target position.SUMMARY OF THE INVENTION

[0006] Example embodiments of the present invention provide systems for propelling watercraft, watercraft, and methods of propelling watercraft that each enhance the execution of a keeping function.

[0007] A system for propelling a watercraft according to an example embodiment of the present invention includes a primary propulsion device, an auxiliary propulsion device, a tilt mechanism, an execution command input, and a controller. The primary propulsion device is attached to a hull of the watercraft. The auxiliary propulsion device is attached to the hull and includes an electric motor as a power source thereof. The tilt mechanism is configured to change a tilt angle of the auxiliary propulsion device with respect to the hull. The execution command input is configured to issue a command to execute a keeping function to keep the hull either at a predetermined target position or oriented in a predetermined target compass direction. The controller is configured or programed to execute the keeping function by setting either the predetermined target position or the predetermined target compass direction based on the tilt angle of the auxiliary propulsion device when the command to execute the keeping function is issued by the execution command input.

[0008] A method of propelling a watercraft according to another example embodiment of the present invention uses a system for propelling the watercraft and including a primary propulsion device, an auxiliary propulsion device, and a tilt mechanism. The primary propulsion device is attached to a hull of the watercraft. The auxiliary propulsion device is attached to the hull and includes an electric motor as a power source thereof. The tilt mechanism is configured to change a tilt angle of the auxiliary propulsion device with respect to the hull. The method includes issuing a command to execute a keeping function to keep the hull either at a predetermined target position or oriented in a predetermined target compass direction, setting either the predetermined target position or the predetermined target compass direction based on the tilt angle of the auxiliary propulsion device when the command to execute the keeping function is issued, and executing the keeping function to keep the hull either at the predetermined target position based on the tilt angle or oriented in the predetermined target compass direction based on the tilt angle.

[0009] When the command to execute the keeping function is issued by the execution command input, either the target position or the target compass direction is set based on the tilt angle of the auxiliary propulsion device. Thus, even if the watercraft is shifted in position or compass direction by external factors until the auxiliary propulsion device is tilted down and then starts operating, it is possible to set, for instance, a position or a compass direction, in which the hull is located or oriented when the auxiliary propulsion device becomes operable, as the target position or the target compass direction. Because of this, it is possible to reduce displacement between the target position and a position in which the hull is located when the keeping function is executed or the displacement between the target compass direction and a compass direction in which the hull is oriented when the keeping function is executed such that execution of the keeping function is enhanced.

[0010] The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the example embodiments with reference to the attached drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 is a plan view of a watercraft including a watercraft propulsion system according to an example embodiment of the present invention.

[0012] FIG. 2 is a side view of the watercraft.

[0013] FIG. 3 is a diagram showing a configuration of a primary propulsion device.

[0014] FIG. 4 is a diagram showing a configuration of an auxiliary propulsion device.

[0015] FIG. 5 is a rear view of the auxiliary propulsion device as seen from behind the watercraft.

[0016] FIG. 6 is a schematic diagram showing a configuration of a drive unit.

[0017] FIGS. 7A to 7C are diagrams including FIG. 7A as a schematic diagram showing the watercraft in which the auxiliary propulsion device is in a tilt-up position, FIG. 7B as a schematic diagram showing the watercraft in which the auxiliary propulsion device is in an intermediate position in transition from the tilt-up position to a tilt-down position, and FIG. 7C as a schematic diagram showing the watercraft in which the auxiliary propulsion device is in the tilt-down position.

[0018] FIG. 8 is a diagram showing a configuration of the watercraft propulsion system installed in the watercraft.

[0019] FIG. 9 is a perspective view of a joystick unit.

[0020] FIG. 10 is a schematic diagram for explaining how to set a target position in a keeping mode.

[0021] FIG. 11 is a schematic diagram for explaining how to set a target compass direction in the keeping mode.

[0022] FIG. 12 is a flowchart showing a series of control actions to be executed by the watercraft propulsion system.DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

[0023] Example embodiments of the present invention will be hereinafter explained with reference to drawings.

[0024] FIG. 1 is a plan view of a watercraft 1 including a watercraft propulsion system (a system for propelling a watercraft)100 according to an example embodiment of the present invention. FIG. 2 is a side view of the watercraft 1 including the watercraft propulsion system 100.

[0025] The watercraft 1 includes a hull 2, a primary propulsion device 3, and an auxiliary propulsion device 4. The primary propulsion device 3 is an engine propulsion device including an engine as a power source thereof, e.g., an internal combustion engine. The primary propulsion device 3 is an outboard motor. The auxiliary propulsion device 4 is an electric propulsion device including an electric motor as a power source thereof. The auxiliary propulsion device 4 is an outboard motor. The auxiliary propulsion device 4 has a smaller rated output than the primary propulsion device 3. The primary and auxiliary propulsion devices 3 and 4 are attached to a stern 2a of the hull 2. The primary and auxiliary propulsion devices 3 and 4 are aligned on the stern 2a in the right-and-left direction of the hull 2. The primary propulsion device 3 is located at the middle of the hull 2 in the right-and-left direction. The auxiliary propulsion device 4 is located on an outer side (the left side in the present example embodiment) of the middle of the hull 2 in the right-and-left direction.

[0026] The hull 2 includes an operating seat 5, a steering wheel 6, a remote control lever 7, a joystick 8, and a gauge 9. The operating seat 5 is where a user (or watercraft operator) is seated when operating the hull 2. The steering wheel 6 is operable by the user to change the route of the watercraft 1. The remote control lever 7 is operable by the user to change the magnitude (output) and the direction (forward or rearward moving direction) of a thrust generated from the primary propulsion device 3 and corresponds to an accelerator. The joystick 8 is operable by the user to operate the watercraft 1 instead of using the steering wheel 6 and the remote control lever 7.

[0027] FIG. 3 is a diagram showing a configuration of the primary propulsion device 3. The watercraft 1 includes an attachment mechanism 11 to attach the primary propulsion device 3 to the hull 2. The attachment mechanism 11 includes a clamp bracket 12, a tilt shaft 13, a swivel bracket 14, and a steering shaft 15. The clamp bracket 12 is detachably fixed to a transom plate provided on the stern 2a of the hull 2. The tilt shaft 13 is horizontally disposed in the clamp bracket 12 along the right-and-left direction. The swivel bracket 14 is joined to the clamp bracket 12 while being pivotable about the tilt shaft 13. The steering shaft 15 is attached to the swivel bracket 14. The primary propulsion device 3 is attached to the swivel bracket 14 while being pivotable about the steering shaft 15. Accordingly, when the primary propulsion device 3 is pivoted about the steering shaft 15, it is possible to change a rudder angle (a compass directional angle formed by a thrust direction with respect to the center line of the hull 2). Additionally, when the swivel bracket 14 is pivoted about the tilt shaft 13, it is possible to change a trim angle of the primary propulsion device 3. The trim angle refers to an angle at which the primary propulsion device 3 is attached to the hull 2.

[0028] The primary propulsion device 3 includes an engine cover 16 (top cowling), an upper case 17, and a lower case 18. The engine cover 16, the upper case 17, and the lower case 18 define a housing of the primary propulsion device 3. The upper case 17 is disposed on the lower side of the engine cover 16. The lower case 18 is disposed on the lower side of the upper case 17.

[0029] The primary propulsion device 3 includes an engine 19, a drive shaft 20, a shift mechanism 21, a propeller shaft 22, a propeller 23, and a shift rod 24. The engine 19 is a prime mover. The engine 19 is disposed inside ethe engine cover 16. The engine 19 is disposed such that the axis of a crankshaft thereof is disposed along the up-and-down direction. The drive shaft 20 is coupled to the lower end of the crankshaft. The drive shaft 20 transmits a mechanical power of the engine 19 to the propeller shaft 22 through the shift mechanism 21. The shift mechanism 21 is disposed on the lower end of the drive shaft 20. The propeller shaft 22 extends rearward from the lower side of the drive shaft 20 in the horizontal direction. The propeller shaft 22 is a rotational shaft of the propeller 23. The propeller 23 is disposed on the rear side of a lower portion of the lower case 18. The propeller 23 is a propulsion member for the watercraft 1. The propeller 23 is fixed to the propeller shaft 22. The shift rod 24 operates the shift mechanism 21.

[0030] The shift mechanism 21 has a plurality of shift positions (shift states) including a forward moving position, a rearward moving position, and a neutral position. The neutral position is a shift position in which the rotation of the drive shaft 20 is not transmitted to the propeller shaft 22. The forward moving position is a shift position in which the rotation of the drive shaft 20 is transmitted to the propeller shaft 22 so as to rotate the propeller shaft 22 in a forward moving rotational direction. The rearward moving position is a shift position in which the rotation of the drive shaft 20 is transmitted to the propeller shaft 22 so as to rotate the propeller shaft 22 in a rearward moving rotational direction. The forward moving rotational direction refers to a direction in which the propeller 23 is rotated to apply a thrust oriented in the forward moving direction to the hull 2. The rearward moving rotational direction refers to a direction in which the propeller 23 is rotated to apply a thrust oriented in the rearward moving direction to the hull 2. The shift mechanism 21 is switched in shift position by the shift rod 24. The shift rod 24 extends in the up-and-down direction while being in parallel to the drive shaft 20. The shift rod 24 is configured to operate the shift mechanism 21 when rotated about the axis thereof.

[0031] The primary propulsion device 3 includes a starter motor 25, an electric power generator 26, an engine ECU (Electric Control Unit) 27, and a throttle actuator 28. The starter motor 25 starts the engine 19. The starter motor 25 is controlled by the engine ECU 27. The electric power generator 26 generates electric power which is then supplied to electric components included in the primary propulsion device 3. The electric power generated by the electric power generator 26 is used to charge a battery 130 on the hull 2. The throttle actuator 28 actuates a throttle valve 29 in the engine 19 so as to change the throttle opening degree thereof to change an amount of intake air in the engine 19. The throttle actuator 28 may include, for instance, an electric motor. The action of the throttle actuator 28 is controlled by the engine ECU27.

[0032] The engine ECU 27 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 engine ECU 27 stores programs and data to control the starter motor 25, the throttle actuator 28, a shift actuator 30, a tilt / trim actuator 35 (to be described below), and so forth based on command signals transmitted thereto from a remote control ECU 106.

[0033] The primary propulsion device 3 includes the shift actuator 30. The shift actuator 30 drives the shift rod 24 so as to change the shift position of the shift mechanism 21. The shift actuator 30 may include, for instance, an electric motor. The shift actuator 30 is controlled by the engine ECU 27.

[0034] The primary propulsion device 3 includes a steering rod 31, a steering device 32, and a steering ECU 34. The steering rod 31 is fixed to the upper case 17. The steering device 32 is joined to the steering rod 31. The steering device 32 drives the steering rod 31 in accordance with an operation of the steering wheel 6. The primary propulsion device 3 is pivoted about the steering shaft 15 by the steering device 32. Accordingly, a rudder angle control is enabled. The steering device 32 includes a steering actuator 33. The steering actuator 33 is controlled by the steering ECU 34.

[0035] The steering ECU 34 includes a processor such as a CPU and memories such as a RAM and a ROM. The steering ECU 34 stores programs and data to control the steering actuator 33 based on either an operating angle signal transmitted thereto from a steering wheel unit 65 (to be described below) or a rudder angle command signal transmitted thereto from the remote control ECU 106. The steering actuator 33 may include an electric motor, or alternatively, may include a hydraulic actuator.

[0036] The watercraft 1 includes the tilt / trim actuator 35. The tilt / trim actuator 35 changes the trim angle of the primary propulsion device 3 with respect to the hull 2. The tilt / trim actuator 35 includes, for instance, a fluid pressure cylinder. The tilt / trim actuator 35 is controlled by the engine ECU 27. The tilt / trim actuator 35 causes the swivel bracket 14 to pivot about the tilt shaft 13 such that the primary propulsion device 3 is pivoted about the tilt shaft 13.

[0037] FIG. 4 is a diagram showing a configuration of the auxiliary propulsion device 4. FIG. 5 is a rear view of the auxiliary propulsion device 4 as seen from behind the watercraft 1.

[0038] The watercraft 1 includes a bracket 41 to attach the auxiliary propulsion device 4 to the hull 2. The bracket 41 is attached to the stern 2a of the hull 2. The auxiliary propulsion device 4 is supported by the bracket 41.

[0039] The auxiliary propulsion device 4 includes a base 42, an upper housing 43, a lower housing 44, a cover 45, a cowl 46, a drive unit 47, and a steering unit 48. The base 42 is supported by the bracket 41. The upper housing 43 extends downward from the base 42. The lower housing 44 may be in the shape of a tube (duct) and is disposed below the upper housing 43. The cover 45 covers the base 42 from below. The cowl 46 covers the base 42 from above.

[0040] The drive unit 47 is disposed inside the lower housing 44. FIG. 6 is a schematic diagram showing a configuration of the drive unit 47. The drive unit 47 includes a propeller 49 and an electric motor 50. The propeller 49 generates a thrust. The electric motor 50 drives the propeller 49. The electric motor 50 includes a rotor 51 and a stator 52.

[0041] The rotor 51 may have the shape of a tube to which the propeller 49 is fixed on the radially inner side thereof. The rotor 55 is rotatably supported by the lower housing 44. The rotor 51 includes a plurality of permanent magnets 53. The permanent magnets 53 are disposed along the circumferential direction of the rotor 51. It should be noted that in FIG. 6, the reference numeral 53 indicates only one of the permanent magnets without indicating the remaining permanent magnets.

[0042] The stator 52 encloses the rotor 51 from radially outside. The stator 52 is fixed to the lower housing 44. The stator 52 includes a plurality of coils 54. The coils 54 are disposed along the circumferential direction of the stator 52. When the coils 54 are electrified, electromagnetic forces are generated such that the rotor 51 is rotated. The propeller 49 is rotated in accordance with the rotation of the rotor 51 such that the thrust can be generated. It should be noted that in FIG. 6, the reference numeral 54 indicates only one of the coils without indicating the remaining coils.

[0043] As shown in FIG. 4, the steering unit 48 is disposed in a space between the cover 45 and the cowl 46. The steering unit 48 changes right and left the direction of the thrust generated by the drive unit 47. The steering unit 48 includes a steering shaft 55 and a steering motor 56. The steering shaft 55 is joined to the upper and lower housings 43 and 44. The steering motor 56 generates a driving force to rotate the steering shaft 55 about the axis thereof. The steering unit 48 may include a reduction gear that reduces the speed of the rotation of the steering motor 56 and transmits the rotation reduced in speed to the steering shaft 55. When the steering motor 56 is driven, the upper and lower housings 43 and 44 are rotated about the steering shaft 55 such that the direction of the thrust generated by the drive unit 47 is changeable right and left.

[0044] The watercraft 1 includes a tilt unit 60 and a tilt angle sensor 61. The tilt unit 60 includes a tilt cylinder 62 (exemplary tilt mechanism). The tilt cylinder 62 may be a hydraulic cylinder of an electric pump type that an electric pump that causes a hydraulic oil to flow. The tilt cylinder 62 is rotatably joined at one end thereof to a lower support portion 41a of the bracket 41. The tilt cylinder 62 is rotatably joined at the other end thereof to the base 42 through a cylinder coupling bracket 63. The bracket 41 supports a tilt shaft 64 at an upper support portion 41b thereof. The base 42 is joined to the bracket 41 through the tilt shaft 64, while being rotatable about the tilt shaft 64. The tilt shaft 64 extends in the right-and-left direction of the hull 2. The base 42 is configured to be rotatable with respect to the bracket 41 in the up-and-down direction. Accordingly, the auxiliary propulsion device 4 is movable up and down by rotating about the tilt shaft 64 with respect to the hull 2 (see arrows A and B in FIG. 4).

[0045] A motion of the auxiliary propulsion device 4 rotated about the tilt shaft 64 to elevate will be referred to as a tilt-up motion (see arrow A in FIG. 4). A motion of the auxiliary propulsion device 4 rotated about the tilt shaft 64 to lower will be referred to as a tilt-down motion (see arrow B in FIG. 4). When the tilt cylinder 62 is driven to expand and contract, the tilt-up and tilt-down motions are enabled. When the propeller 49 is elevated to be above the surface of the water by the tilt-up motion, the auxiliary propulsion device 4 is disposed in a tilt-up position P1 (see FIG. 7A to be described below). When the propeller 49 is lowered to be submerged into the water by the tilt-down motion, the auxiliary propulsion device 4 is disposed in a tilt-down position P2 (see FIG. 7C to be described below). The tilt unit 60 can be regarded as an elevating and lowering device to elevate and lower the propeller 49. FIG. 4 shows the auxiliary propulsion device 4 disposed in the tilt-down position. It should be noted that FIGS. 7A to 7C omit illustration of the primary propulsion device 3 for easy understanding.

[0046] The tilt angle sensor 61 detects the tilt angle of the auxiliary propulsion device 4 with respect to the hull 2. The tilt angle sensor 61 detects the angle of the auxiliary propulsion device 4 with respect to the bracket 41. It is possible to detect in which of the tilt-up and tilt-down positions P1 and P2 the auxiliary propulsion device 4 is disposed based on the detection by the tilt angle sensor 61. The tilt angle sensor 61 may be a position sensor to detect the position of an actuating rod in the tilt cylinder 62. As an alternative example, the tilt angle sensor 61 may be a potentiometer.

[0047] The tilt angle will be explained further in detail. As shown in FIG. 4, a line L is defined as an imaginary straight line that extends perpendicular to the steering shaft 55 and extends through the tilt shaft 64 in a side view. FIG. 7A is a schematic diagram showing a state that the auxiliary propulsion device 4 is disposed in the tilt-up position P1. FIG. 7B is a diagram showing a state that the auxiliary propulsion device 4 is disposed in an intermediate position in transition from the tilt-up position P1 to the tilt-down position P2. FIG. 7C is a schematic diagram showing a state that the auxiliary propulsion device 4 is disposed in the tilt-down position P2. As shown in FIG. 7A, the straight line L is indicated by a reference sign Lu in the tilt-up position P1 of the auxiliary propulsion device 4. A tilt angle θ is set to gradually increase with transition from the tilt-up position P1 to the tilt-down position P2. The tilt angle θ can be defined as an angle formed between the straight line Lu and the straight line L in the position of the auxiliary propulsion device 4 shown in FIG. 7B. As shown in FIG. 7C, the tilt angle θ is maximized when the auxiliary propulsion device 4 is disposed in the tilt-down position P2.

[0048] FIG. 8 is a diagram showing a configuration of the watercraft propulsion system 100 installed in the watercraft 1. The watercraft propulsion system 100 includes the primary and auxiliary propulsion devices 3 and 4 described above. The watercraft propulsion system 100 includes a main controller 101, an intra-watercraft network (CAN (Controller Area Network)) 102, an outboard motor control network 103, a control panel network 104, the steering wheel unit 65, a remote control unit 70, the remote control ECU 106, a joystick unit 80, a GPS (Global Positioning System) receiver 108, and a compass sensor 109. The main controller 101 controls the hull 2 as a whole. The main controller 101 includes a processor such as a CPU and memories such as a RAM and a ROM. The main controller 101 stores programs and data to control the hull 2 as a whole. The main controller 101 is connected to the intra-watercraft network 102 in the hull 2.

[0049] The remote control unit 70, the joystick unit 80, the remote control ECU 106, the GPS receiver 108, and the compass sensor 109 are connected to the intra-watercraft network 102.

[0050] The remote control ECU 106, the steering wheel unit 65, and both the engine ECU 27 and the steering ECU 34 in the primary propulsion device 3 are connected to the outboard motor control network 103. The main controller 101, the remote control ECU 106, the gauge 9, and the auxiliary propulsion device 4 are connected to the control panel network 104. Signals may be transmitted and received in the intra-watercraft network 102, the outboard motor control network 103, and the control panel network 104 through either wired communication or wireless communication, or alternatively, through the Internet.

[0051] The main controller 101 transmits and receives signals to and from a plurality of units connected to the intra-watercraft network 102 and controls the primary and auxiliary propulsion devices 3 and 4 and the other units. The main controller 101 has a plurality of control modes and controls the respective units in aspects preliminarily set in accordance with the control modes, respectively.

[0052] The steering wheel unit 65 is connected to the outboard motor control network 103. The steering wheel unit 65 outputs an operating angle signal, indicating the operating angle of the steering wheel 6, to the outboard motor control network 103. The operating angle signal is received by the remote control ECU 106 and the steering ECU 34. The steering ECU 34 responds to either the operating angle signal generated by the steering wheel unit 65 or a rudder angle command generated by the remote control ECU 106 and controls the steering actuator 33 in response to either the operating angle signal or the rudder angle command. Accordingly, the rudder angle of the primary propulsion device 3 is controlled.

[0053] The remote control unit 70 includes the remote control lever 7. The remote control unit 70 generates and outputs an operating position signal, indicating the operating position of the remote control lever 7, to the intra-watercraft network 102.

[0054] The joystick unit 80 includes the joystick 8. The joystick unit 80 generates an operating position signal indicating the operating position of the joystick 8. The joystick unit 80 includes operating buttons 81 to 85. The joystick unit 80 generates operating signals of the operating buttons 81 to 85 disposed thereon. The joystick unit 80 will be described in detail in paragraphs below.

[0055] The remote control ECU 106 includes a processor such as a CPU and memories such as a RAM and a ROM. The remote control ECU 106 stores programs and data to execute controls to be described below. The remote control ECU 106 outputs a thrust command to the engine ECU 27 through the outboard motor control network 103. The thrust command includes a shift command to instruct a shift position and an output command to instruct an engine output (e.g., engine rotational speed). The remote control ECU 106 outputs the rudder angle command to the steering ECU 34 through the outboard motor control network 103.

[0056] The remote control ECU 106 executes different control actions depending on the control modes of the main controller 101. For example, in a control mode for operating the watercraft 1 (watercraft operating mode) with the steering wheel 6 and the remote control lever 7, the remote control ECU 106 outputs the thrust command (the shift command and the output command) to the engine ECU 27 in accordance with the operating position signal generated by the remote control unit 70. The remote control ECU 106 outputs the rudder angle command to the steering ECU 34 in accordance with the operating angle signal generated by the steering wheel unit 65.

[0057] On the other hand, in a control mode for operating the watercraft 1 without operating the steering wheel 6 and the remote control lever 7, the remote control ECU 106 operates in accordance with the command issued by the main controller 101. The remote control ECU 106 outputs the thrust command (the shift command and the output command) to the engine ECU 27 in accordance with an operating position signal generated by the main controller 101. The remote control ECU 106 outputs the rudder angle command to the steering ECU 34 in accordance with the operating angle signal generated by the main controller 101.

[0058] For example, in the control mode for operating the watercraft 1 with the joystick 8, the main controller 101 generates the thrust command (the shift command and the output command) and the rudder angle command in accordance with the signal generated by the joystick unit 80 and outputs the thrust command and the rudder angle command to the primary propulsion device 3 through the remote control ECU 106.

[0059] The engine ECU 27 drives the shift actuator 30 in accordance with the shift command so as to control the shift position. The engine ECU 27 drives the throttle actuator 28 in accordance with the output command so as to control the throttle opening degree. The steering ECU 34 drives the steering actuator 33 in accordance with the rudder angle command so as to control the rudder angle of the primary propulsion device 3.

[0060] The auxiliary propulsion device 4 includes a motor controller 110 and a steering controller 111. The motor controller 110 and the steering controller 111 are connected to the intra-watercraft network 102. The motor controller 110 and the steering controller 111 are configured or programmed to actuate the auxiliary propulsion device 4 in response to commands outputted thereto from the main controller 101. The main controller 101 outputs a thrust command and a rudder angle command to the auxiliary propulsion device 4. The thrust command includes a shift command (rotational direction command) and an output command. The shift command is a rotational direction command to cause the propeller 49 to stop, rotate in a forward moving rotational direction, or rotate in a rearward moving rotational direction. The output command instructs a magnitude of the thrust to be generated, i.e., a target value for the thrust (as well as the rotational speed). The rudder angle command instructs a target value for the rudder angle.

[0061] The motor controller 110 controls the electric motor 50 in accordance with the shift command (rotational direction command) and the output command. The motor controller 110 includes a processor such as a CPU and memories such as a RAM and a ROM. The motor controller 110 stores programs and data to control the electric motor 50.

[0062] The steering controller 111 controls the steering motor 56 in accordance with the rudder angle command. The steering controller 111 includes a processor such as a CPU and memories such as a RAM and a ROM. The steering controller 111 stores programs and data to control the steering motor 56.

[0063] The main controller 101 outputs a tilt command to the motor controller 110 through the intra-watercraft network 102. The motor controller 110 causes the tilt cylinder 62 to expand and contract in accordance with a tilt command signal such that the auxiliary propulsion device 4 is moved to either the tilt-up position P1 or the tilt-down position P2. The tilt command signal includes a tilt-down command signal and a tilt-up command signal. The tilt-down command signal causes the tilt cylinder 62 to contract such that the auxiliary propulsion device 4 is changed in position from the tilt-up position P1 to the tilt-down position P2. The tilt-up command signal causes the tilt cylinder 62 to expand such that the auxiliary propulsion device 4 is changed in position from the tilt-down position P2 to the tilt-up position P1. The tilt command signal is outputted from the main controller101 not only to the motor controller 110 but also to the steering controller 111. When the tilt-up command signal is outputted to the motor controller 110 and the steering controller 111, the motor controller 110 and the steering controller 111 stop the electric motor 50 and the steering motor 56, respectively. In other words, the auxiliary propulsion device 4 is stopped without being driven in the tilt-up position P1.

[0064] The motor controller 110 receives a detection signal inputted thereto from the tilt angle sensor 61. Accordingly, the motor controller 110 obtains information regarding the tilt angle of the auxiliary propulsion device 4 and is able to transmit the information regarding the tilt angle to the main controller 101.

[0065] The GPS receiver 108 receives radio waves from artificial satellites circulating about the Earth, specifies the position of the watercraft 1, and outputs not only position data indicating the position of the watercraft 1 but also velocity data indicating the moving speed of the watercraft 1. The position data and the velocity data are obtained by the main controller 101 and are used to display or control at least either the position or the compass direction of the watercraft 1.

[0066] The compass sensor 109 detects the compass direction of the watercraft 1 and generates compass direction data. The compass direction data are obtained by the main controller 101.

[0067] The gauge 9 is connected to the main controller 101 through the control panel network 104. The gauge 9 displays a variety of information for operating the watercraft 1. The gauge 9 is connected to the remote control ECU 106, the motor controller 110, and the steering controller 111 through the control panel network 104. The gauge 9 displays a variety of information regarding the operating state of the primary propulsion device 3, that of the auxiliary propulsion device 4, the position or the compass direction of the watercraft 1, and so forth. The gauge 9 may be provided with an input 9a including a touchscreen, one or more buttons, and so forth. When operated by the user, the input 9a may be configured to output an operating signal to the control panel network 104 such that various settings or commands are executable.

[0068] The watercraft propulsion system 100 includes a power switch unit 120. The power switch unit 120 is operable by the user to power on the primary propulsion device 3 and then further start and stop the engine 19. The power switch unit 120 includes a power switch 121 (exemplary primary propulsion device command input), a start switch 122, and a stop switch 123. The power switch 121 powers on and off the primary propulsion device 3. The start switch 122 starts the engine 19. The stop switch 123 stops the engine 19.

[0069] When the power switch 121 is turned on, the remote control ECU 106 executes a control to provide power to the primary propulsion device 3. When the power switch 121 is turned on, a power supply relay (not illustrated in the drawing), interposed between the battery 130 (e.g., 12V) and the primary propulsion device 3, is turned on. When the start switch 122 is operated, while the primary propulsion device 3 is in a powered-on state, the remote control ECU 106 issues a start command to the engine ECU 27. Accordingly, the engine ECU 27 actuates the starter motor 25 (see FIG. 3) to start the engine 19. While the engine 19 is operating, the battery 130 is charged with the electric power generated by the electric power generator 26 (see FIG. 3). When the stop switch 123 is operated, while the engine 19 is operating, the remote control ECU 106 issues a stop command to the engine ECU 27. In response to the stop command, the engine ECU 27 executes a control to stop the engine 19. The remote control ECU 106 outputs primary propulsion device state information, indicating whether or not the primary propulsion device 3 is in the powered-on state and whether or not the engine 19 is operating, to the main controller 101 through the intra-watercraft network 102.

[0070] The watercraft propulsion system 100 includes a power switch unit 140. The power switch unit 140 is connected to the auxiliary propulsion device 4 to power on or power off the auxiliary propulsion device 4. The power switch unit 140 includes a power switch 141 (exemplary auxiliary propulsion device command input) configured such that when the power switch 141 is turned on or turned off, a circuit between the auxiliary propulsion device 4 and a battery 145 (e.g., a 48V battery) that provides electric power to the auxiliary propulsion device 4 is closed or opened to power on or off the auxiliary propulsion device 4. The motor controller 110 is configured or programmed to output auxiliary propulsion device state information, indicating whether or not the auxiliary propulsion device 4 is in a powered-on state, i.e., whether or not the auxiliary propulsion device 4 is in a drivable state, to the main controller 101 through the intra-watercraft network 102. The battery 145 is configured to receive the electric power generated by the electric power generator 26 (see FIG. 3) in the primary propulsion device 3 through a DC / DC converter 146 (voltage converter).

[0071] The watercraft propulsion system 100 includes an application switch panel 150. The application switch panel 150 is connected to the intra-watercraft network 102. The application switch panel 150 includes a plurality of function switches 151, each of which is configured to issue a command to execute a function preliminarily defined in association therewith. For example, the function switches 151 may include a switch to issue a command to operate the watercraft 1 in an automated manner. More specifically, the function switches 151 may include a switch associated with automated steering to keep the compass direction of the watercraft 1, a switch associated with automated steering to keep the route of the watercraft 1, a switch associated with automated steering to cause the watercraft 1 to sequentially pass through a plurality of specified spots, a switch associated with automated steering to move the watercraft 1 in a predetermined sailing pattern (a zigzag pattern, a spiral pattern, etc.), and so forth.

[0072] Additionally, the function switches 151 may include a switch associated with a function to move the auxiliary propulsion device 4 to either the tilt-up position P1 or the tilt-down position P2. In FIG. 8, a reference numeral 152 is assigned to the function switches to move the auxiliary propulsion device 4 to either the tilt-up position P1 or the tilt-down position P2. The function switches 152 to execute a tilt operation include a tilt-up switch 152a and a tilt-down switch 152b. When the tilt-up switch 152a is operated by the user, a tilt-up command signal is outputted to the main controller 101 which outputs the tilt-up command signals to the motor controller 110 and the steering controller 111. On the other hand, when the tilt-down switch 152b is operated by the user, a tilt-down command signal is outputted to the main controller 101 so that the main controller 101 outputs the tilt-down command signals to the motor controller 110 and the steering controller 111.

[0073] The main controller 101 executes controls for the primary and auxiliary propulsion devices 3 and 4 in a plurality of control modes. The control modes include a plurality of modes depending on the states of the primary and auxiliary propulsion devices 3 and 4. Specifically, the control modes include an electric mode, an engine mode, a dual mode, and an extender mode. The main controller 101 operates in any of the control modes based on the primary propulsion device state information and the auxiliary propulsion device state information.

[0074] The electric mode is a control mode executed when the auxiliary propulsion device 4 is in the powered-on state but the primary propulsion device 3 is in a powered-off state. The electric mode is a control mode executed to cause only the auxiliary propulsion device 4 to generate a thrust. The engine mode is a control mode executed when the primary propulsion device 3 is in the powered-on state and the engine 19 is operating but the auxiliary propulsion device 4 is in a powered-off state. In other words, the engine mode is a control mode to cause only the primary propulsion device 3 to generate a thrust. The dual mode and the extender mode are control modes executed when the auxiliary propulsion device 4 is in the powered-on state and the engine 19 is operating in the primary propulsion device 3. The dual mode is a control mode to utilize both the thrusts generated by the primary and auxiliary propulsion devices 3 and 4. The extender mode is a control mode to utilize only the thrust generated by the auxiliary propulsion device 4 and the engine 19 operates to generate electric power to charge the battery 145. From the perspective of generating thrusts, the electric mode and the extender mode are identical to each other. Which one to select between the dual mode and the extender mode may be made by a setting or command by the user. For example, such a setting or command is made by operating the input 9a provided in the gauge 9. Alternatively, the dual mode and the extender mode may be switched by the main controller 101 in an automated manner depending on the magnitude of the thrust. For example, the dual mode and the extender mode are switchable in accordance with operating a thrust setting button 85 provided in the joystick unit 80 (to be described below) to regulate (increase and reduce) the magnitude of a thrust.

[0075] FIG. 9 is a perspective view of the joystick unit 80. The joystick unit 80 includes the joystick 8 able to tilt forward, rearward, rightward, and leftward (i.e., in all compass directions of 360 degrees) and also turn (twist) about the axis thereof. The joystick unit 80 includes a joystick button 81, keeping mode setting buttons 82 to 84, and the thrust setting button 85.

[0076] The joystick button 81 is operable by the user when a joystick mode, which is a control mode (watercraft operating mode) using the joystick 8, is selected by the user.

[0077] The keeping mode setting buttons 82 to 84 are operable by the user to set control modes related to keeping the position and / or the compass direction (each of which is an exemplary keeping function). Specifically, the keeping mode setting button82 is operable to set a fixed spot keeping mode (called Stay Point™ mode) to keep both the position of the watercraft 1 and the compass direction of the bow (or the stern) of the watercraft 1. The keeping mode setting button 83 is operable to set a position keeping mode (called Fish Point™ mode) to keep the position of the watercraft 1 without keeping the compass direction of the bow (or the stern) of the watercraft 1. The keeping mode setting button 84 is operable to setting a compass direction keeping mode (called Drift Point™ mode) to keep the compass direction of the bow (or the stern) of the watercraft 1 without keeping the position of the watercraft 1. The fixed spot keeping mode, the position keeping mode, and the compass direction keeping mode are examples of the keeping function.

[0078] When each of the keeping mode setting buttons 82 to 84 is operated by the user, a signal to start a keeping mode associated therewith is outputted to the main controller 101. Then, when each of the keeping mode setting buttons 82 to 84 is operated again by the user, a signal to stop the keeping mode associated therewith is outputted to the main controller 101. For example, when the keeping mode setting button 82 is operated by the user, the fixed spot keeping mode is executed and, then, when the keeping mode setting button 82 is operated again by the user, a signal to stop the fixed spot keeping mode is outputted to the main controller 101.

[0079] The thrust setting button 85 is operable by the user to sett the thrust of the auxiliary propulsion device 4. The thrust setting button 85 includes a plus button 85a and a minus button 85b. For example, the magnitude of the thrust is set in a plurality of stages. When the plus button 85a is operated, the thrust is increased in magnitude. When the minus button 85b is operated, the thrust is reduced in magnitude. The setting, made by the thrust setting button 85, is outputted as an output signal to the main controller 101. When the magnitude of the thrust is set in a stage greater than or equal to a predetermined stage, the main controller 101 sets the dual mode as the control mode. On the other hand, when the magnitude of the thrust is set in a stage less than the predetermined stage, the main controller 101 sets the extender mode as the control mode.

[0080] The control modes for the main controller 101 can be classified as a normal mode, a joystick mode, and a keeping mode.

[0081] The normal mode executes a steering control in accordance with the operating angle signal generated by the steering wheel unit 65 and executes a thrust control in accordance with the operating signal (operating position signal) of the remote control lever 7. The normal mode is, for instance, a default control mode of the main controller 101. The steering control refers to, specifically, a control action executed by the steering ECU 34 to drive the steering actuator 33 in accordance with the operating angle signal generated by the steering wheel unit 65 or the rudder angle command outputted from the remote control ECU 106. Accordingly, the body of the primary propulsion device 3 pivots right and left to change the rudder angle such that the direction of the thrust is changed right and left with respect to the hull 2. The thrust control refers to, specifically, a control action executed by the engine ECU 27 to drive the shift actuator 30 and the throttle actuator 28 in accordance with the thrust command (the shift command and the output command) issued from the remote control ECU 106 to the engine ECU 27. Accordingly, the forward moving position, the rearward moving position, or the neutral position is set as the shift position in the primary propulsion device 3 and, simultaneously, the engine output (specifically, the engine rotational speed) is changed.

[0082] The joystick mode executes the steering control and the thrust control in accordance with the operating signal of the joystick 8 in the joystick unit 80.

[0083] In the joystick mode, the steering control and the thrust control are executed for the primary propulsion device 3 in a state that a thrust is generated by the primary propulsion device 3. In other words, the main controller 101 issues the steering angle command and the thrust command to the remote control ECU 106. Then, the remote control ECU 106 outputs the steering angle command and the thrust command to the steering ECU 34 and the engine ECU 27, respectively. The state that a thrust is generated by the primary propulsion device 3 is made when the power switch 121 is turned on.

[0084] Additionally, in the joystick mode, the steering control and the thrust control are executed for the auxiliary propulsion device 4 in a state that a thrust is generated by the auxiliary propulsion device 4. The steering control executed for the auxiliary propulsion device 4 refers to, specifically, a control action executed by the steering controller 111 in the auxiliary propulsion device 4 to control and cause the steering motor 56 to drive the steering unit 48 in accordance with the steering angle command issued from the main controller 101 to the steering controller 111. Accordingly, the drive unit 47 and the upper housing 43 in the auxiliary propulsion device 4 pivot right and left such that the direction of the thrust is changed right and left with respect to the hull 2. The thrust control executed for the auxiliary propulsion device 4 refers to, specifically, an action executed by the motor controller 110 in the auxiliary propulsion device 4 to control the rotational direction and the rotational speed of the electric motor 50 in accordance with the thrust command (the shift command and the output command) outputted from the main controller 101 to the motor controller 110. Accordingly, the rotational direction of the propeller 49 is set to either the forward moving rotational direction or the rearward moving rotational direction and, simultaneously, the rotational speed of the propeller 49 is changed. The state that a thrust is generated by the auxiliary propulsion device 4 is made when the power switch 141 is turned on.

[0085] The fixed spot keeping mode (Stay Point™ mode), the position keeping mode (Fish Point™ mode), and the compass direction keeping mode (Drift Point™ mode), set by operating the keeping mode setting buttons 82, 83, and 84, respectively, as described above are examples of the keeping function. In the keeping modes, the output and the rudder angle of at least one of the primary and auxiliary propulsion devices 3 and 4 are controlled without any manual operation by the watercraft operator.

[0086] For example, in the fixed spot keeping mode (Stay Point™ mode), the main controller 101 controls the output and the rudder angle of at least one of the primary and auxiliary propulsion devices 3 and 4 based on the position data and the velocity data, both of which are generated by the GPS receiver 108, and the compass direction data generated by the compass sensor 109. Accordingly, fluctuations in position and compass direction of the hull 2 are reduced or prevented.

[0087] On the other hand, in the position keeping mode (Fish Point™ mode), the main controller 101 controls the output and the rudder angle of at least one of the primary and auxiliary propulsion devices 3 and 4 based on the position data and the velocity data, both of which are generated by the GPS receiver 108. Accordingly, fluctuations in position of the hull 2 are reduced or prevented.

[0088] Yet on the other hand, in the compass direction keeping mode (Drift Point™ mode), the main controller 101 controls the output and the rudder angle of at least one of the primary and auxiliary propulsion devices 3 and 4 based on the compass direction data generated by the compass sensor 109. Accordingly, fluctuations in compass direction of the hull 2 are reduced or prevented.

[0089] The keeping mode setting buttons 82, 83, and 84 are examples of an execution command input to issue a command to execute the keeping function.

[0090] The following explanation relates to controls to be executed when the keeping mode setting buttons 82, 83, and 84 are operated. First, explanation will be provided for controls to be executed when the keeping mode setting buttons 82, 83, and 84 are operated in the electric mode and the auxiliary propulsion device 4 is in the powered-on state but the primary propulsion device 3 is in the powered-off state.

[0091] In the electric mode, when the keeping mode setting button 83 is operated, if the auxiliary propulsion device 4 is disposed in the tilt-down position P2, the main controller 101 executes the position keeping mode (Fish Point™ mode) by setting a position, in which the watercraft 1 is located when the keeping mode setting button 83 is operated, as a target position and by causing the auxiliary propulsion device 4 to operate. When the keeping mode setting button 84 is operated, if the auxiliary propulsion device 4 is disposed in the tilt-down position P2, the main controller 101 executes the compass direction keeping mode (Drift Point™ mode) by setting a compass direction, in which the watercraft 1 is oriented when the keeping mode setting button 84 is operated, as a target compass direction and by causing the auxiliary propulsion device 4 to operate. When the keeping mode setting button 82 is operated, if the auxiliary propulsion device 4 is disposed in the tilt-down position P2, the main controller 101 executes the fixed spot keeping mode (Stay Point™ mode) by setting a position and a compass direction, in which the watercraft 1 is located and oriented when the keeping mode setting button 82 is operated, as a target position and a target compass direction and by causing the auxiliary propulsion device 4 to operate.

[0092] When the keeping mode setting button 83 is operated, if the auxiliary propulsion device 4 is disposed in the tilt-up position P1, the main controller 101 generates a tilt-down command signal and outputs the tilt-down command signal to the motor controller 110. When obtaining the tilt-down command signal, the motor controller 110 causes the tilt cylinder 62 to contract such that the auxiliary propulsion device 4 is moved toward the tilt-down position P2 such that the auxiliary propulsion device 4 is changed in tilt angle. The main controller 101 executes the position keeping mode (Fish Point™ mode) by setting a position, in which the hull 2 is located when the tilt angle θ becomes a predetermined threshold θs or greater, as a target position Tp (see FIG. 10 to be described below). The main controller 101 executes the position keeping mode by causing the auxiliary propulsion device 4 to operate. The predetermined threshold θs can be set as, for instance, a value of the tilt angle at which the auxiliary propulsion device 4 is disposed in an operable position. The operable position can be set as, for instance, a position in which the propeller 49 is submerged in part into the water or a position in which the center axis of the propeller 49 is submerged into the water.

[0093] Additionally, when the keeping mode setting button 84 is operated, if the auxiliary propulsion device 4 is disposed in the tilt-up position P1, the main controller 101 generates a tilt-down command signal and outputs the tilt-down command signal to the motor controller 110. When obtaining the tilt-down command signal, the motor controller 110 causes the tilt cylinder 62 to contract such that the auxiliary propulsion device 4 is moved toward the tilt-down position P2 such that the auxiliary propulsion device 4 is changed in tilt angle. The main controller 101 executes the compass direction keeping mode (Drift Point™ mode) by setting a compass direction, in which the hull 2 is oriented when the tilt angle θ becomes the predetermined threshold θs or greater, as a target compass direction Td (see FIG. 11 to be described).

[0094] Yet on the other hand, when the keeping mode setting button 82 is operated, if the auxiliary propulsion device 4 is disposed in the tilt-up position P1, the main controller 101 generates a tilt-down command signal and outputs the tilt-down command signal to the motor controller 110. When obtaining the tilt-down command signal, the motor controller 110 causes the tilt cylinder 62 to contract such that the auxiliary propulsion device 4 is moved toward the tilt-down position P2 such that the auxiliary propulsion device 4 is changed in tilt angle. The main controller 101 executes the fixed spot keeping mode (Stay Point™ mode) by setting a position and a compass direction, in which the hull 2 is located and oriented when the tilt angle θ becomes the predetermined threshold θs or greater, as the target position Tp and the target compass direction Td.

[0095] FIG. 10 is a schematic diagram for explaining how to set the target position in the position keeping mode and the fixed spot keeping mode. In FIG. 10, the following state is assumed for explaining how to set the target position in these keeping modes: the auxiliary propulsion device 4 is in the powered-on state as a result of operating the power switch unit 140 and is disposed in the tilt-up position P1. A diagram depicted in a right upper portion of FIG. 10 shows a plan view of the watercraft 1, whereas a diagram depicted in a right lower portion FIG. 10 shows a side view of the watercraft 1. In the state of the watercraft 1 depicted in the right portion of FIG. 10, the auxiliary propulsion device 4 is in the powered-on state and is disposed in the tilt-up position P1. When either the keeping mode setting button 82 or 83 is operated in the state of the watercraft 1, the main controller 101 drives the tilt cylinder 62 to move the auxiliary propulsion device 4 toward the tilt-down position P2 such that the auxiliary propulsion device 4 is changed in tilt angle. As shown in FIG. 10, when an external adverse factor, oriented in a direction of arrow C, acts on the watercraft 1 due to the flow of tide or so forth, the watercraft 1 is supposed to move until the tilt angle θ reaches the predetermined threshold θs. Then, as indicated by the watercraft 1 depicted on a left side of FIG. 10, when the tilt angle θ reaches the predetermined threshold θs, a position, in which the watercraft 1 is located at that point in time, is set as the target position Tp. The watercraft 1, shifted in position by an external factor, is depicted with dashed two-dotted line. It should be noted that in FIG. 10, the side views omit illustration of the primary propulsion device 3 for easy understanding.

[0096] Thus, even when either the keeping mode setting button 82 or 83 is operated, if the auxiliary propulsion device 4 is disposed in the tilt-up position P1, the keeping mode associated with the operated one of the keeping mode setting buttons 82 and 83 is executed by setting, as the target position Tp, a position that the watercraft 1 is kept shifting from a position Sp, in which the watercraft 1 is located when either the keeping mode setting button 82 or 83 is operated, until the tilt angle θ reaches the threshold θs. It should be noted that, when either the keeping mode setting button 82 or 83 is operated to execute the keeping mode associated therewith, if the auxiliary propulsion device 4 is disposed in the tilt-down position P2, the position Sp, in which the watercraft 1 is located when either the keeping mode setting button 82 or 83 is operated, is set as the target position Tp.

[0097] On the other hand, FIG. 11 is a schematic diagram for explaining how to set the target compass direction in the compass direction keeping mode and the fixed spot keeping mode. In FIG. 11, the following state is assumed for explaining how to set the target compass direction in the compass direction keeping mode and the fixed spot keeping mode: the auxiliary propulsion device 4 is in the powered-on state as a result of operating the power switch unit 140 and is disposed in the tilt-up position P1. A diagram depicted in a right upper portion of FIG. 11 shows a plan view of the watercraft 1, whereas a diagram depicted in a right lower portion of FIG. 11 shows a side view of the watercraft 1. In the state of the watercraft 1 depicted in the right side of FIG. 11, the auxiliary propulsion device 4 is in the powered-on state and is disposed in the tilt-up position P1. When either the keeping mode setting button 82 or 84 is operated in the state of the watercraft 1, the main controller 101 drives the tilt cylinder 62 to move the auxiliary propulsion device 4 toward the tilt-down position P2 such that the auxiliary propulsion device 4 is changed in tilt angle. As shown in FIG. 11, when an external adverse factor acts on the watercraft 1 due to the flow of tide or so forth such that the watercraft 1 is rotated in a direction of arrow D, the watercraft 1 is supposed to be changed in compass direction until the tilt angle θ reaches the predetermined threshold θs. Then, as indicated by the watercraft 1 depicted in a left side of FIG. 11, when the tilt angle θ reaches the predetermined threshold θs, a compass direction, in which the watercraft 1 is oriented at that point in time, is set as the target compass direction Td. The watercraft 1, changed in compass direction by the external adverse factor, is depicted with dashed two-dotted line. It should be noted that in FIG. 11, the side views omit illustration of the primary propulsion device 3 for easy understanding.

[0098] Thus, even when either the keeping mode setting button 82 or 84 is operated, if the auxiliary propulsion device 4 is disposed in the tilt-up position P1, the keeping mode associated with the operated one of the keeping mode setting buttons 82 and 84 is executed by setting, as the target compass direction Td, a compass direction that the watercraft 1 is shifted from a compass direction Sd, in which the watercraft 1 is oriented when either the keeping mode setting button 82 or 84 is operated, until the tilt angle θ reaches the threshold θs. It should be noted that, when either the keeping mode setting button 82 or 84 is operated to execute the keeping mode associated therewith, if the auxiliary propulsion device 4 is disposed in the tilt-down position P2, the compass direction Sd, in which the watercraft 1 is oriented when either the keeping mode setting button 82 or 84 is operated, is set as the target compass direction Td.

[0099] It should be noted that the engine 19 in the primary propulsion device 3 operates only to generate electric power in the extender mode. Thus, when any of the keeping mode setting buttons 82, 83, and 84 is operated, a control to be executed in the extender mode is identical to that to be executed in the electric mode.

[0100] When the keeping mode setting button 83 is operated in the engine mode and the auxiliary propulsion device 4 is in the powered-off state but the primary propulsion device 3 is in the powered-on state, the main controller 101 executes the position keeping mode by setting the position Sp, in which the watercraft 1 is located when the keeping mode setting button 83 is operated, as the target position Tp and by causing the primary propulsion device 3 to operate. When the keeping mode setting button 84 is operated in the engine mode, the main controller 101 executes the compass direction keeping mode by setting the compass direction Sd, in which the watercraft 1 is oriented when the keeping mode setting button 84 is operated, as the target compass direction Td and by causing the primary propulsion device 3 to operate. When the keeping mode setting button 82 is operated in the engine mode, the main controller 101 executes the fixed spot keeping mode by setting the position Sp and the compass direction Sd, in which the watercraft 1 is located and oriented when the keeping mode setting button 82 is operated, as the target position Tp and the target compass direction Td and by causing the primary propulsion device 3 to operate.

[0101] Next, explanation will be provided for controls to be executed when any of the keeping mode setting buttons 82, 83, and 84 is operated in the dual mode.

[0102] When the keeping mode setting button 83 is operated in the dual mode, if the auxiliary propulsion device 4 is disposed in the tilt-down position P2, the main controller 101 executes the keeping mode by setting the position Sp, in which the watercraft 1 is located when the keeping mode setting button 83 is operated, as the target position Tp and by controlling the primary and auxiliary propulsion devices 3 and 4. When the keeping mode setting button 84 is operated in the dual mode, if the auxiliary propulsion device 4 is disposed in the tilt-down position P2, the main controller 101 executes the compass direction keeping mode by setting the compass direction Sd, in which the watercraft 1 is oriented when the keeping mode setting button 84 is operated, as the target compass direction Td and by controlling the primary and auxiliary propulsion devices 3 and 4. When the keeping mode setting button 82 is operated in the dual mode, if the auxiliary propulsion device 4 is disposed in the tilt-down position P2, the main controller 101 executes the fixed spot keeping mode by setting the position Sp and the compass direction Sd, in which the watercraft 1 is located and oriented when the keeping mode setting button 82 is operated, as the target position Tp and the target compass direction Td and by controlling the primary and auxiliary propulsion devices 3 and 4.

[0103] By contrast, when the keeping mode setting button 83 is operated in the dual mode, if the auxiliary propulsion device 4 is disposed in the tilt-up position P1, the main controller 101 drives the tilt cylinder 62 to move the auxiliary propulsion device 4 toward the tilt-down position P2 such that the auxiliary propulsion device 4 is changed in tilt angle The main controller 101 executes the position keeping mode by setting the position, in which the hull 2 is located when the tilt angle θ becomes the predetermined threshold θs or greater, as the target position Tp and by causing the primary and auxiliary propulsion devices 3 and 4 to operate. The primary propulsion device 3 stands by without being caused to operate until the tilt angle reaches the predetermined threshold θs and is then caused to operate together with the auxiliary propulsion device 4. When the keeping mode setting button 84 is operated in the dual mode, if the auxiliary propulsion device 4 is disposed in the tilt-up position P1, the main controller 101 drives the tilt cylinder 62 to move the auxiliary propulsion device 4 toward the tilt-down position P2 such that the auxiliary propulsion device 4 is changed in tilt angle. Then, the main controller 101 executes the compass direction keeping mode by setting the compass direction, in which the hull 2 is oriented when the tilt angle θ becomes the predetermined threshold θs or greater, as the target compass direction Td and by causing the primary and auxiliary propulsion devices 3 and 4 to operate. At this time, the primary propulsion device 3 stands by without being caused to operate until the tilt angle reaches the predetermined threshold θs and is then caused to operate together with the auxiliary propulsion device 4. When the keeping mode setting button 82 is operated in the dual mode, if the auxiliary propulsion device 4 is disposed in the tilt-up position P1, the main controller 101 drives the tilt cylinder 62 to move the auxiliary propulsion device 4 toward the tilt-down position P2 such that the auxiliary propulsion device 4 is changed in tilt angle. Then, the main controller 101 executes the fixed spot keeping mode by setting the position and the compass direction, in which the hull 2 is located and oriented when the tilt angle θ becomes the predetermined threshold θs or greater, as the target position Tp and the target compass direction Td and by causing the primary and auxiliary propulsion devices 3 and 4 to operate. At this time, the primary propulsion device 3 stands by without being caused to operate until the tilt angle reaches the predetermined threshold θs and is then caused to operate together with the auxiliary propulsion device 4.

[0104] It should be noted that, when either the primary propulsion device 3 or the auxiliary propulsion device 4 is in the powered-on or powered-off state as a result of operating either the power switch unit 120 or the power switch unit 140 during execution of the keeping mode, the main controller 101 deactivates the execution of the keeping mode.

[0105] Next, a series of control actions to be executed by the watercraft propulsion system 100 will be explained and, simultaneously, a method of propelling a watercraft will be described as well.

[0106] FIG. 12 is a flowchart showing a series of control actions to be executed by the watercraft propulsion system 100 according to an example embodiment.

[0107] In step S1, when any of the keeping mode setting buttons 82, 83, and 84 is operated by the user, the main controller 101 receives a start signal from the operated one of the keeping mode setting buttons 82, 83, and 84.

[0108] Next, in step S2, the main controller 101 determines whether or not the auxiliary propulsion device 4 is in the powered-on state. The auxiliary propulsion device 4 is configured to be powered on when the power switch 141 in the power switch unit 140 is operated to be turned on.

[0109] When it is determined that the auxiliary propulsion device 4 is in the powered-on state, the main controller 101 determines whether or not the auxiliary propulsion device 4 is disposed in the tilt-up position P1 in step S3. The main controller 101 is able to determine whether or not the auxiliary propulsion device 4 is disposed in the tilt-up position P1 based on a value of the tilt angle detected by the tilt angle sensor 61.

[0110] When it is determined that the auxiliary propulsion device 4 is disposed in the tilt-up position P1, the main controller 101 generates a tilt-down command signal and outputs the tilt-down command signal to the motor controller 110 in step S4. Accordingly, the motor controller 110 causes the tilt cylinder 62 to contract such that the auxiliary propulsion device 4 starts performing the tilt-down motion.

[0111] Next, in step S5, the main controller 101 determines whether or not the tilt angle θ detected by the tilt angle sensor 61 is greater than or equal to the threshold θs. When the tilt angle θ is less than the threshold θs, the determination process in step S5 is repeated until the tilt angle θ becomes the threshold θs or greater. When the tilt angle θ is greater than or equal to the threshold θs in step S5, the control process proceeds to step S6.

[0112] In step S6, the main controller 101 sets at least either the target position Tp or the target compass direction Td in accordance with the operated one of the keeping mode setting buttons 82, 83, and 84. For example, when the keeping mode setting button operated in step S1 is the keeping mode setting button 83, the main controller 101 obtains the present position of the hull 2 from the GPS receiver 108 and sets the present position of the hull 2 as the target position Tp in step S6. When the keeping mode setting button operated in step S1 is the keeping mode setting button 84, the main controller 101 obtains the present compass direction of the hull 2 from the compass sensor 109 and sets the present compass direction of the hull 2 as the target compass direction Td in step S6. When the keeping mode setting button operated in step S1 is the keeping mode setting button 82, the main controller 101 executes the following control actions in step S6. The main controller 101 obtains the present position of the hull 2 from the GPS receiver 108 and sets the present position of the hull2 as the target position Tp. Additionally, the main controller 101 obtains the present compass direction of the hull 2 from the compass sensor 109 and sets the present compass direction of the hull 2 as the target compass direction Td.

[0113] Next, in step S7, the main controller 101 executes one of the keeping modes, which is associated with the operated one of the keeping mode setting buttons 82, 83, and 84, by controlling the auxiliary propulsion device 4. Here, in the case of the dual mode, the keeping mode is executed by controlling not only the auxiliary propulsion device 4 but also the primary propulsion device 3.

[0114] Next, in step S8, the main controller 101 determines whether or not the main controller 101 has received a signal indicating that the primary propulsion device 3 or the auxiliary propulsion device 4 is in the powered-on or powered-off state as a result of operating the power switch 121 in the power switch unit 120 or the power switch 141 in the power switch unit 140. When having not received the signal indicating that the primary propulsion device 3 or the auxiliary propulsion device 4 is in the powered-on state or the powered-off state, the main controller 101 determines whether or not the main controller 101 has received a signal to stop the keeping mode in step S9.

[0115] When it is determined that the main controller 101 has received the signal to stop the keeping mode in step S9, the control process ends. Contrarily, when it is determined that the main controller 101 has not received the signal to stop the keeping mode in step S9, the control process returns to step S8.

[0116] Incidentally, in step S8, when it is determined that the main controller 102 has received the signal indicating that the primary propulsion device 3 or the auxiliary propulsion device 4 is in the powered-on state or the powered-off state, the main controller 101 stops the keeping mode in step S10.

[0117] It should be noted that in step S3, when it is determined that the auxiliary propulsion device 4 is disposed in the tilt-down position P2 and not in the tilt-up position P1, the control process proceeds to step S6. Then, at least either the target position Tp or the target compass direction Td is set in accordance with the keeping mode setting button operated in step S1. In this case, the position Sp, in which the watercraft 1 is located when the keeping mode setting button 83 is operated, is set as the target position Tp. The compass direction Sd, in which the watercraft 1 is oriented when the keeping mode setting button 84 is operated, is set as the target compass direction Td. The position Sp and the compass direction Sd, in which the watercraft 1 is located and oriented when the keeping mode setting button 82 is operated, are set as the target position Tp and the target compass direction Td.

[0118] Incidentally, in step S2, when the auxiliary propulsion device 4 is in the powered-off state, the control processing proceeds to step S11. Then, the main controller 101 determines whether or not the primary propulsion device 3 is in the powered-on state in step S11. The primary propulsion device 3 is configured to be powered on when the power switch 121 in the power switch unit 120 is operated to be turned on.

[0119] In step S11, when it is determined that the primary propulsion device 3 is in the powered-off state, the keeping mode cannot be executed and, thus, the control process ends.

[0120] Contrarily, in step S11, when it is determined that the primary propulsion device 3 is in the powered-on state, the control process proceeds to step S6. Then, the main controller 101 executes at least one of the following: setting the present position Sp of the hull 2 as the target position Tp and setting the present compass direction Sd of the hull 2 as the target compass direction Td. Specifically, at least one of the following is executed: setting the position Sp, in which the watercraft 1 is located when any of the keeping mode setting buttons 82, and 83 is operated, as the target position Tp and setting the compass direction Sd, in which the watercraft 1 is oriented when any of the keeping mode setting buttons 82, and 84 is operated, as the target compass direction Td. Then, in step S7, the main controller 101 executes one of the keeping modes that is associated with the operated one of the keeping mode setting buttons 82, 83, and 84.

[0121] The watercraft 1 and the watercraft propulsion system 100 according to example embodiments of the present invention have the following features.

[0122] When any of the keeping mode setting buttons 82, 83, and 84 is operated to issue a command to execute one of the keeping modes, even if the watercraft 1 is shifted in position or compass direction by an external adverse factor until the auxiliary propulsion device 4 is tilted down and then starts operating, the keeping mode is executed by setting the target position Tp based on the tilt angle θ of the auxiliary propulsion device 4 such that it is possible to execute, for instance, setting a position, in which the watercraft 1 is located when the auxiliary propulsion device 4 becomes operable, as the target position Tp, or setting a compass direction, in which the watercraft 1 is oriented when the auxiliary propulsion device 4 becomes operable, as the target compass direction Td. Because of this, it is possible to reduce displacement between the target position Tp and a position in which the watercraft 1 is located when the keeping mode is executed or displacement between the target compass direction Td and a compass direction in which the watercraft 1 is oriented when the keeping mode is executed such that the keeping mode is able to be executed.

[0123] When the command to execute the keeping mode is issued, if the auxiliary propulsion device 4 is disposed in the tilt-up position P1, the tilt cylinder 62 is driven to move the auxiliary propulsion device 4 toward the tilt-down position P2 such that the auxiliary propulsion device 4 is changed in tilt angle θ. Then, the keeping mode is executed by setting the position, in which the hull 2 is located when the tilt angle θ becomes the predetermined threshold θs or greater, as the target position Tp, or by setting the compass direction, in which the hull 2 is oriented when the tilt angle θ becomes the predetermined threshold θs or greater, as the target compass direction Td. Accordingly, it is possible to reduce displacement between the target position Tp and the position in which the hull 2 is located when the keeping mode is executed or displacement between the target compass direction Td and the compass direction in which the hull 2 is oriented when the keeping mode is executed such that the keeping mode is able to be executed.

[0124] When the command to execute the keeping mode is issued, if the auxiliary propulsion device 4 is disposed in the tilt-down position P2, the keeping mode is executed by setting the position Sp, in which the hull 2 is located when the command to execute the keeping mode is issued, as the target position Tp, or by setting the compass direction Sd, in which the hull 2 is oriented when the command to execute the keeping mode is issued, as the target compass direction Td. Accordingly, when the command to execute the keeping mode is issued, if the auxiliary propulsion device 4 is disposed in the tilt-down position P2, it is possible to promptly execute the keeping mode after the issuance of the command.

[0125] When a command to execute one of the keeping modes is issued by one of the keeping mode setting buttons 82, 83, and 84, while the auxiliary propulsion device 4 is in a started state, the keeping mode is executed by setting the target position Tp or the target compass direction Td based on the tilt angle θ of the auxiliary propulsion device 4 and by controlling the auxiliary propulsion device 4. Accordingly, while the auxiliary propulsion device 4 is in the powered-on state, it is possible to set the target position Tp or the target compass direction Td based on the tilt angle θ.

[0126] When a power-on or power-off command is issued from the power switch 121 or 141 during execution of the keeping mode, the execution of the keeping mode is stopped. Accordingly, when either the auxiliary propulsion device 4 or the primary propulsion device 3 is operated to be powered on or powered off, it is possible to stop the keeping mode.

[0127] When the command to execute one of the keeping modes is issued by one of the keeping mode setting buttons 82, 83, and 84, if the auxiliary propulsion device 4 is in the started state but the primary propulsion device 3 is not in a started state, the keeping mode is executed by controlling the auxiliary propulsion device 4. Accordingly, it is possible to execute the keeping mode only by the auxiliary propulsion device 4.

[0128] When the command to execute one of the keeping modes is issued by one of the keeping mode setting buttons 82, 83, and 84, if both the primary and auxiliary propulsion devices 3 and 4 are in the started states, the keeping mode is executed by controlling both the primary and auxiliary propulsion devices 3 and 4. Accordingly, it is possible to execute the keeping mode by both the primary and auxiliary propulsion devices 3 and 4.

[0129] When the command to execute the fixed spot keeping mode is issued by the keeping mode setting button 82, the fixed spot keeping mode is executed by setting the target position Tp and the target compass direction Td based on the tilt angle θ of the auxiliary propulsion device 4. Accordingly, it is possible to reduce displacement between the target position Tp and a position in which the hull 2 is located when the fixed spot keeping mode is executed and displacement between the target compass direction Td and a compass direction in which the hull 2 is located when the fixed spot keeping mode is executed such that the fixed spot keeping mode is able to be executed.

[0130] 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.

[0131] In an example embodiment described above, the primary propulsion device 3 uses the engine as the power source thereof, however, the primary propulsion device 3 may not be limited to this configuration. The primary propulsion device 3 may include an electric motor as the power source thereof.

[0132] In an example embodiment described above, the tilt angle θ is set to gradually increase with transition from the tilt-up position P1 to the tilt-down position P2, however, the tilt angle θ may not be limited to this configuration. The tilt angle θ may be set to gradually increase with transition from the tilt down-position P2 to the tilt-up position P1.

[0133] In an example embodiment described above, in the process of step S3, it is determined in which of the tilt-up position P1 and the tilt-down position P2 the auxiliary propulsion device 4 is disposed based on the value of the tilt angle detected by the tilt angle sensor 61, however, the determination process in step S3 may not be limited to this configuration. The auxiliary propulsion device 4 is disposed in only the tilt-up position P1 or the tilt-down position P2. Thus, the main controller 101 may be configured or programmed to store the present position when receiving the tilt-up command signal or the tilt-down command signal.

[0134] According to example embodiments of the present invention, it is possible to provide system for propelling watercraft, watercraft, and methods of propelling a watercraft that each enhance execution of a keeping function.

[0135] 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.

Claims

1. A system for propelling a watercraft, the system comprising:a primary propulsion device attached to a hull of the watercraft;an auxiliary propulsion device attached to the hull and including an electric motor as a power source;a tilt mechanism to change a tilt angle of the auxiliary propulsion device with respect to the hull;an execution command input to issue a command to execute a keeping function to keep the hull either at a predetermined target position or oriented in a predetermined target compass direction; anda controller configured or programed to execute the keeping function by setting either the predetermined target position or the predetermined target compass direction based on the tilt angle of the auxiliary propulsion device when the command to execute the keeping function is issued by the execution command input.

2. The system according to claim 1, whereinthe tilt mechanism is configured to move the auxiliary propulsion device between a tilt-down position and a tilt-up position, the auxiliary propulsion device in the tilt-down position causes a propeller thereof to be submerged in water, and the auxiliary propulsion device in the tilt-up position causes the propeller to be above a surface of water;the tilt angle is configured to increase incrementally from the tilt-up position to the tilt-down position; andwhen the auxiliary propulsion device is in the tilt-up position when the command to execute the keeping function is issued, the controller is configured or programed to drive the tilt mechanism to move the auxiliary propulsion device toward the tilt-down position and execute the keeping function by either setting a position in which the hull is located when the tilt angle becomes a predetermined threshold or greater as the predetermined target position or setting a compass direction in which the hull is oriented when the tilt angle becomes the predetermined threshold or greater as the predetermined target compass direction.

3. The system according to claim 1, whereinthe tilt mechanism is configured to move the auxiliary propulsion device between a tilt-down position and a tilt-up position, the auxiliary propulsion device in the tilt-down position causes a propeller thereof to be submerged in water, and the auxiliary propulsion device in the tilt-up position causes the propeller to be above a surface of water;the tilt angle is configured to incrementally increase from the tilt-up position to the tilt-down position; andwhen the auxiliary propulsion device is in the tilt-down position when the command to execute the keeping function is issued, the controller is configured or programed to execute the keeping function by either setting a position in which the hull is located when the command to execute the keeping function is issued as the predetermined target position or setting a compass direction in which the hull is oriented when the command to execute the keeping function is issued as the predetermined target compass direction.

4. The system according to claim 1, further comprising:an auxiliary propulsion device command input to issue a command to start or stop the auxiliary propulsion device; whereinwhen the auxiliary propulsion device is in a started state when the command to execute the keeping function is issued by the execution command input, the controller is configured or programed to execute the keeping function by setting either the predetermined target position or the predetermined compass direction based on the tilt angle of the auxiliary propulsion device and by controlling the auxiliary propulsion device.

5. The system according to claim 1, further comprising:an auxiliary propulsion device command input to issue a command to start or stop the auxiliary propulsion device; anda primary propulsion device command input to issue a command to start or stop the primary propulsion device; whereinwhen the command is issued by either the auxiliary propulsion device command input or the primary propulsion device command input during execution of the keeping function, the controller is configured or programed to stop the execution of the keeping function.

6. The system according to claim 1, further comprising:an auxiliary propulsion device command input to issue a command to start or stop the auxiliary propulsion device; anda primary propulsion device command input to issue a command to start or stop the primary propulsion device; whereinwhen the auxiliary propulsion device is in a started state but the primary propulsion device is not in a started state when the command to execute the keeping function is issued by the execution command input, the controller is configured or programed to execute the keeping function by controlling the auxiliary propulsion device.

7. The system according to claim 1, further comprising:an auxiliary propulsion device command input to issue a command to start or stop the auxiliary propulsion device; anda primary propulsion device command input to issue a command to start or stop the primary propulsion device; whereinwhen the auxiliary propulsion device and the primary propulsion device is in a started state when the command to execute the keeping function is issued by the execution command input, the controller is configured or programed to execute the keeping function by controlling not only the auxiliary propulsion device but also the primary propulsion device.

8. The system according to claim 1, whereinthe keeping function keeps the hull at the predetermined target position and oriented in the predetermined target compass direction; andwhen the command to execute the keeping function is issued by the execution command input, the controller is configured or programed to execute the keeping function by setting the predetermined target position and the predetermined target compass direction based on the tilt angle of the auxiliary propulsion device.

9. The system according to claim 1, wherein the primary propulsion device is an engine propulsion device including an engine as a power source thereof.

10. A watercraft comprising:a hull; andthe system according to claim 1 on the hull.

11. A method of propelling a watercraft using a system including a primary propulsion device, an auxiliary propulsion device, and a tilt mechanism, the primary propulsion device attached to a hull of the watercraft, the auxiliary propulsion device attached to the hull, the auxiliary propulsion device including an electric motor as a power source thereof, the tilt mechanism configured to change a tilt angle of the auxiliary propulsion device with respect to the hull, the method comprising:issuing a command to execute a keeping function of keeping the hull either at a predetermined target position or oriented in a predetermined target compass direction;setting either the predetermined target position or the predetermined target compass direction based on the tilt angle of the auxiliary propulsion device when the command to execute the keeping function is issued; andexecuting the keeping function to keep the hull either at the predetermined target position based on the tilt angle or oriented in the predetermined target compass direction based on the tilt angle.

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