CONTROL DEVICE FOR A MARINE VESSEL, MARINE VESSEL AND METHOD FOR CONTROLLING A MARINE VESSEL

Abstract

 A control device for a marine vessel (1) includes a hull (2), at least a pair of resistance members (93), an acquisition unit (70), and a control unit (71). The resistance members (93) are arranged on the hull (2), one on the left and one on the right, each independently drivable and movable between a first position, where the resistance received from water in a predetermined direction is adjusted to a first magnitude, and a second position, where the resistance is adjusted to zero or to a second magnitude smaller than the first magnitude. The acquisition unit (70) acquires the relative distance (D) between a buoy (36), which floats on the water in a free-drifting manner, and the hull (2). The control unit (71) controls the resistance members (93) based on the relative distance (D).

Description

[0001] The present invention relates to a control device for a marine vessel, a marine vessel and a method for controlling a marine vessel.

[0002] Among fishing methods primarily involving small marine vessels, there is a technique commonly known as drift fishing, in which the hull of a vessel is allowed to drift freely with the tidal current without anchoring while fishing. In drift fishing, depending on the difference between the tidal current direction and the wind direction, as well as the wind speed, the effects on the hull and the fishing line may differ, sometimes causing the two to move differently. As a result, issues such as fishing line entanglement may arise, which may impede comfortable drift fishing.

[0003] If a buoy with a shape designed to be less susceptible to wind is floated on water, and the vessel is maneuvered to follow the buoy, the vessel is expected to move along with the tidal current, making drift fishing more comfortable. JP H09-295600 A discloses a technology for automatically maneuvering a marine vessel so as to maintain a constant relative distance between the vessel and an ocean buoy. However, when the conventional technology is applied to control a vessel to follow a buoy, frequent use of a propulsion device is required, resulting in reduced quietness, which makes this technology not necessarily suitable for drift fishing.

[0004] Meanwhile, JP 2851130 B, JP H11-43097 A, and JP 2000-142584 A disclose technologies in which a resistance member, such as a sea anchor, that receives water resistance is submerged in water, allowing the hull to be more strongly affected by the tidal current than by the wind. However, in these conventional technologies, since the resistance member is operated manually, it is not easy to maneuver the hull to move in line with the fishing line.

[0005] It is an object of the present disclosure to provide a control device for a marine vessel, a marine vessel and a method for controlling a marine vessel configured to facilitate a comfortable drift fishing environment.

[0006] According to the present invention said object is solved by control device for a marine vessel having the features of independent claim 1. Moreover, said object is solved by a marine vessel according to claim 14. Furthermore, said object is solved by a method for controlling a marine vessel having the features of independent claim 15. Preferred embodiments are laid down in the dependent claims.

[0007] In one embodiment, a control device for a marine vessel includes a hull, at least a pair of resistance members, an acquisition unit, and a control unit. The resistance members are arranged on the hull, one on the left and one on the right, each independently drivable and movable between a first position, where the resistance received from water in a predetermined direction is adjusted to a first magnitude, and a second position, where the resistance is adjusted to zero or to a second magnitude smaller than the first magnitude. The acquisition unit acquires the relative distance between a buoy, which floats on the water in a free-drifting manner, and the hull. The control unit controls the resistance members based on the relative distance.

[0008] In this configuration, the resistance members can be driven independently and are arranged in at least one pair on the hull, with one on the left and one on the right. The resistance members are movable between the first position, where the resistance received from water in a predetermined direction is adjusted to the first magnitude, and the second position, where the resistance is adjusted to zero or to the second magnitude smaller than the first magnitude. The relative distance between the buoy, which floats on the water in a free-drifting manner, and the hull is acquired, and the resistance members are controlled based on the relative distance.

[0009] 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 preferred embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] 

FIGS. 1A and 1B are schematic top views of a marine vessel.

FIGS. 2A to 2D are schematic right-side views of the marine vessel.

FIG. 3 is a block diagram of a marine propulsion system.

FIG. 4 is a flowchart of a drift fishing mode process.

FIGS. 5A to 5E are schematic diagrams illustrating an example of control in the drift fishing mode process.

FIGS. 6A and 6B are schematic diagrams illustrating modifications in the arrangement of resistance plate units.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Exemplary embodiments will be described in detail with reference to the accompanying drawings.

[0012] FIGS. 1A and 1B are schematic top views of a marine vessel 1 that uses a control device according to an embodiment. The marine vessel 1 has a hull 2. FIGS. 1A and 1B illustrate the states in which resistance plates 93 (described later) are in a second position and a first position, respectively.

[0013] The centerline C of the hull 2 passes through the center of the stern and the tip of the bow. The centerline C also passes through the center of gravity G (turning center) of the marine vessel 1. The front-rear direction is parallel to the centerline C. The forward direction is a direction upward along the centerline C in FIG. 1A (a direction toward the bow as viewed from the stern). The backward direction is a direction downward along the centerline C in FIG. 1A. As used herein, the terms "left" and "right" are defined based on the perspective when the hull 2 is viewed from the rear. Accordingly, a left-right direction of the marine vessel 1 is a direction to a right side and a left side of the hull 2, respectively. The up-down direction is a direction perpendicular to both the front-rear direction and the left-right direction.

[0014] The marine vessel 1 includes a steerable outboard motor 4 and a steerable trolling motor 5 as propulsion devices for propelling the hull 2. The outboard motor 4 is located at the stern, while the trolling motor 5 is located at the bow. The outboard motor 4 and the trolling motor 5 may serve as the primary and auxiliary propulsion devices of the marine vessel 1, respectively.

[0015] The marine vessel 1 further includes a steering wheel 11 mainly used for steering, a remote control unit 12 mainly used for adjusting the output of the outboard motor 4, and a joystick 13 mainly used for both steering and adjusting the output of the outboard motor 4 (see FIG. 3). The remote control unit 12 includes two throttle levers (not illustrated), which are operated to adjust the engine output of the outboard motor 4 and to switch between forward and reverse travel. Each throttle lever is operable from a neutral position in both the forward and reverse directions.

[0016] As illustrated in FIG. 1A, the outboard motor 4 has an outboard motor body 20 and a propeller 21. The outboard motor body 20 is attached to the stern via an attachment mechanism, specifically to a swivel bracket (not illustrated) of the attachment mechanism so as to be pivotable about the steering axis center K. The steering angle of the outboard motor 4 changes as the outboard motor body 20 pivots about the steering axis center K. The trolling motor 5 is designed to impart a propulsive force to the hull 2 in any direction around the rotation axis J2. For example, the trolling motor 5 may be electrically powered.

[0017] A pair of left and right resistance plate units 90L and 90R are arranged at the stern. The resistance plate units 90L and 90R each include a rotary motor 91, a lifting motor 92, a resistance plate 93 (resistance member), a fixed member 94, and a lifting member 95. The resistance plate units 90L and 90R are arranged and configured symmetrically with respect to the centerline C. The resistance plate units 90L and 90R can be driven independently. Since their basic configurations are the same, the configuration of the resistance plate unit 90L will be described as a representative example.

[0018] The fixed member 94 is fixed to the stern, and the lifting member 95 is movable in the up-down direction relative to the fixed member 94 (at least between a raised position and a lowered position). The resistance plate 93 is pivotable about the rotation axis J1 and is movable to a second position illustrated in FIG. 1A and to a first position illustrated in FIG. 1B. The rotation axis J1 is the axis center of a pivot shaft that is parallel to the up-down direction.

[0019] FIGS. 2A to 2D are schematic right-side views of the marine vessel 1.

[0020] FIGS.2A and 2B illustrate a state where the resistance plate 93 is in the second position, while FIGS. 2C and 2D illustrate a state where the resistance plate 93 is in the first position. FIGS. 2B and 2D illustrate a state where the lifting member 95 is in the raised position, while FIGS. 2A and 2C illustrate a state where the lifting member 95 is in the lowered position in a drift fishing mode other than during normal sailing.

[0021] The lifting motor 92 drives the lifting member 95 to move it up and down relative to the fixed member 94. The rotary motor 91 causes the resistance plate 93 to pivot about the rotational axis J1. The lifting motor 92 and the rotary motor 91 are automatically controlled by a controller 70 (described later) and can also be manually operated using a resistance plate switch (SW) 30 (see FIG. 3).

[0022] The first position is a pivoted position where the resistance plate 93 is perpendicular to the front-rear direction; in this position, the resistance plate 93 forms an angle of 90° with respect to the centerline C as viewed from above. The second position is a pivoted position where the resistance plate 93 is parallel to the front-rear direction; in this position, the resistance plate 93 forms an angle of 0° with respect to the centerline C as viewed from above.

[0023] When at least a portion of the resistance plate 93 is submerged (e.g., when in the lowered position), the resistance received from water in a predetermined direction (the front-rear direction in this embodiment) is at a first magnitude in the first position (90°) and at a second magnitude, smaller than the first magnitude, in the second position (0°). In contrast, when the entire resistance plate 93 is above the water surface, the resistance it receives from water is zero.

[0024] FIG. 3 is a block diagram of a marine propulsion system including the control device for a marine vessel according to the embodiment.

[0025] The marine propulsion system includes the controller 70, the outboard motor 4, the trolling motor 5, the steering wheel 11, the remote control unit 12, the joystick 13, a display 14, various sensors 15, various operators 16, and a memory 17. The marine propulsion system further includes the resistance plate SW 30, a first global navigation satellite system (GNSS) sensor 31, a second GNSS sensor 32, a wind speed sensor 33, a tidal current sensor 34, the resistance plate units 90L and 90R, a receiver 35, and a buoy 36.

[0026] The resistance plate SW 30 includes a left switch 30L and a right switch 30R, which are used to manually operate the resistance plates 93 of the resistance plate units 90L and 90R, respectively.

[0027] The controller 70 includes a CPU 71, a ROM 72, a RAM 73, and a timer (not illustrated). The ROM 72 stores a control program. The CPU 71 loads the control program stored in the ROM 72 into the RAM 73 and executes it, thereby implementing various control operations. The RAM 73 provides a workspace for the CPU 71 to execute the control program.

[0028] The outboard motor 4 includes an engine control unit (ECU) 81, a steering control unit (SCU) 82, a rotational speed sensor 83, an engine 84, a steering mechanism 85, various sensors 86, a steering angle sensor 87, and various actuators 88. The ECU 81 and the SCU 82 each include a CPU (not illustrated). The ECU 81 controls the driving of the engine 84 according to commands from the controller 70. The SCU 82 controls the driving of the steering mechanism 85 according to commands from the controller 70.

[0029] The steering mechanism 85 causes the outboard motor body 20 to pivot about the steering axis center K (see FIG. 1A), thereby changing the orientation of the outboard motor body 20 in the left-right direction. This changes the direction of the propulsive force acting on the stern, where the outboard motor body 20 is mounted. The steering mechanism 85 may be either electric or hydraulic. The various actuators 88 may include a power trim and tilt (PTT) mechanism that causes the outboard motor 4 to pivot about the tilt axis.

[0030] The rotational speed sensor 83 detects the rotation rate (revolutions per unit time) of the engine 84. The various sensors 86 include a throttle opening sensor and the like. The steering angle sensor 87 detects the actual steering angle of the outboard motor 4. Note that the controller 70 may also obtain the actual steering angle from the steering command value output to the steering mechanism 85.

[0031] The trolling motor 5 includes an electric motor 50, a propeller (not illustrated) that generates propulsive force when driven to rotate by the electric motor 50, and an electric steering unit 56 that rotates the electric motor 50 about the rotation axis J2.

[0032] The steering unit 56 includes, for example, a servo motor. The orientation of the trolling motor 5 can be changed by the steering operation of the steering unit 56. Specifically, the steering unit 56 rotates the electric motor 50 about the rotation axis J2 to change its orientation within a range of 360 degrees or more, thereby altering the direction of the propulsive force. This changes the steering angle of the trolling motor 5, which in turn changes the direction of the propulsive force that the trolling motor 5 exerts on the hull 2.

[0033] The trolling motor 5 includes, in addition to the electric motor 50 and the steering unit 56, a motor control unit (MCU) 57, an SCU 58, a steering angle sensor 55, various sensors 60, and an actuator 61.

[0034] The MCU 57 and the SCU 58 each include a CPU (not illustrated). The MCU 57 controls the driving of the electric motor 50 according to commands from the controller 70. The maximum output of the electric motor 50 may be less than that of the engine 84 of the outboard motor 4. The SCU 58 controls the driving of the steering unit 56 according to commands from the controller 70, thereby changing the direction of the propulsive force acting on the bow, where the trolling motor 5 is mounted.

[0035] The actuator 61 moves the trolling motor 5 between a use position and a storage position. Note that it is not essential to provide a function for enabling the trolling motor 5 to transition between the use position and the storage position by power.

[0036] The steering angle sensor 55 detects the steering angle of the trolling motor 5, which changes in response to the steering operation of the steering unit 56. Detection signals from the steering angle sensor 55 and the various sensors 60 are supplied to the controller 70. It is not essential that the hull 2, the outboard motor 4, and the trolling motor 5 be equipped with all the sensors and actuators mentioned above.

[0037] Strictly speaking, the points where the propulsive forces of the propulsion devices act are their respective mounting locations on the hull 2. However, for convenience of explanation, it is assumed herein that the propulsive force of the trolling motor 5 acts on the bow, and the propulsive force of the outboard motor 4 acts at the location of the attachment mechanism at the stern.

[0038] The various sensors 15 include a hull speed sensor, a hull acceleration sensor, an orientation sensor, a distance sensor, an attitude sensor, and a position sensor (not illustrated). The various sensors 15 further include a sensor that detects the operation of the remote control unit 12, a sensor that detects the rotational angle position of the steering wheel 11, a sensor that detects the operation of each switch and paddle on the steering wheel 11, and a sensor that detects the operation of the joystick 13. The hull speed sensor detects the navigation speed (vessel speed) of the marine vessel 1 (hull 2). Detection signals from the various sensors 15 are supplied to the controller 70.

[0039] The various operators 16 include not only operators for maneuvering the marine vessel but also setting operators for making various settings and input operators for entering various instructions (not illustrated). Some of the various operators 16 may be located on the steering wheel 11. The various operators 16 are operated by the vessel operator, and the operation signals are supplied to the controller 70. The memory 17 is a read-write nonvolatile storage medium.

[0040] The controller 70 may establish predetermined communication with the various sensors 15 and the various operators 16 to exchange information with them. The display 14 displays various types of information.

[0041] The first GNSS sensor 31 and the second GNSS sensor 32 periodically receive GNSS signals from GNSS satellites. As a result, the controller 70 can acquire the current position of each of the GNSS sensors 31 and 32. The first GNSS sensor 31 and the second GNSS sensor 32 are located at different positions. For example, the first GNSS sensor 31 and the second GNSS sensor 32 are arranged at different positions along the front-rear direction. Accordingly, it is possible to determine the hull orientation based on the signals received by the GNSS sensors 31 and 32, without the need for an orientation sensor.

[0042] The wind speed sensor 33 detects the wind speed. The tidal current sensor 34 detects the relative tidal current speed and relative tidal current direction as observed from the hull 2. Alternatively, the tidal current sensor 34 may emit ultrasonic waves at an angle into the sea and analyze the reflected ultrasonic waves to determine the relative tidal current speed and relative tidal current direction.

[0043] The controller 70 determines the absolute tidal current speed based on the relative tidal current speed and the vessel speed. The controller 70 also determines the absolute tidal current direction based on the relative tidal current direction and the direction of the vessel's movement. Hereinafter, unless otherwise specified, the terms "tidal current speed" and "tidal current direction" will refer to the absolute tidal current speed and the absolute tidal current direction, respectively.

[0044] The buoy 36 is floated on the water and allowed to drift freely in the drift fishing mode (described later). To minimize the wind effect (resistance), for example, the buoy 36 is designed to protrude less above the water and have a flat top shape. It is desirable for the buoy 36 to move in the same manner as the fishing line, even when exposed to the wind.

[0045] The buoy 36 includes a third GNSS sensor 37 and a transmitter 38. The third GNSS sensor 37 periodically receives GNSS signals from GNSS satellites. This allows the buoy 36 to acquire its current position. The transmitter 38 is configured to output information indicating the position to the outside.

[0046] The receiver 35 receives the information output from the transmitter 38. This allows the controller 70 to acquire the current position of the buoy 36. There is no particular limitation on the communication method between the transmitter 38 and the receiver 35; for example, medium-range or short-range wireless communication may be used.

[0047] The controller 70, functioning as an acquisition unit, acquires the relative distance D between the hull 2 (i.e. a specific reference point on the hull) and the buoy 36 (i.e. a specific reference point on the buoy 36). According to the embodiment the relative distance D the distance between center of gravity G of the hull 2 and the buoy 36 (the specific reference point on the buoy 36, i.e. the center of the buoy 36). For example, the controller 70 acquires the relative distance D based on the current position of the hull 2, which is acquired by the first GNSS sensor 31 or the second GNSS sensor 32, and the current position of the buoy 36, which is acquired by the receiver 35. The relative distance D may be acquired using a distance sensor provided on the hull 2, and the acquisition method may employ radio waves, ultrasound, or light. In this context, it is not essential for the buoy 36 to include the third GNSS sensor 37 and the transmitter 38, nor is it essential for the hull 2 to include the receiver 35.

[0048] The controller 70 also acquires the relative orientation Bθ of the buoy 36 with respect to the hull 2. The relative orientation Bθ is defined as the angle formed between an imaginary line passing through the center of gravity G of the hull 2 (specific reference point on the hull) and the buoy 36 (specific reference point on the buoy), as viewed from above, and the centerline C of the hull 2 (i.e. a line parallel to the centerline C and extending through the specific reference point on the hull), in the forward direction (see FIG. 5A). For example, the controller 70 first acquires the hull orientation from the orientation sensor or the GNSS sensors 31 and 32. The controller 70 then acquires the relative orientation Bθ based on the current position of the hull 2, the current position of the buoy 36, and the hull orientation.

[0049] In this embodiment, there are a plurality of vessel maneuvering modes, which can be broadly classified into an outboard motor mode that does not utilize the trolling motor 5 and a cooperative mode that utilizes both the trolling motor 5 and the outboard motor 4. The outboard motor mode is a maneuvering mode in which the outboard motor 4 is controlled primarily based on the rotational operation of the steering wheel 11 and the operation of the remote control unit 12. Other maneuvering modes include a drift fishing mode, which utilizes the resistance plate units 90L and 90R to achieve operations suitable for drift fishing. In the drift fishing mode, the trolling motor 5 and/or the outboard motor 4 may also be used.

[0050] FIG. 4 is a flowchart of a drift fishing mode process. FIGS. 5A to 5E are schematic diagrams illustrating an example of control in the drift fishing mode process.

[0051] The drift fishing mode process is implemented by the CPU 71, which loads a program stored in the ROM 72 or the like into the RAM 73 and executes it. This process is initiated according to an instruction to start the drift fishing mode received through the various operators 16.

[0052] After the process starts, the CPU 71 monitors the outputs of the sensors and the like and acquires or determines the latest values of the current position of the hull 2, the current position of the buoy 36, the hull orientation, the absolute tidal current direction, the relative orientation Bθ of the buoy 36, and the like at regular time intervals. The absolute tidal current direction need not necessarily be determined using the tidal current sensor 34; it may instead be derived from the temporal changes (trajectory) of the current position of the buoy 36.

[0053] At the start of the process, the vessel operator floats the buoy 36 on the water. At this time, as illustrated in FIG. 5A, the buoy 36 may be connected to the hull 2 with a connecting member 39, such as a flexible string member, to prevent it from being lost.

[0054] In addition, at the start of the process, the vessel operator pre-registers a target relative orientation Tθ, which serves as a target value for the relative orientation Bθ. The target relative orientation Tθ is stored in the memory 17. As an example, the target relative orientation Tθ is set to 90° to the left in the forward direction. Note that, in FIGS. 5A to 5E, the resistance plates 93 of the resistance plate units 90L and 90R are denoted as 93L and 93R, respectively.

[0055] In this process, a first distance D1, a second distance D2, and a third distance D3 are used for comparison with the relative distance D. The relationship among these distances is represented as D1 < D2 < D3. Their values are stored in the memory 17. For drift fishing, an appropriate relative distance D is one that satisfies the condition D1 < D ≤ D2.

[0056] In step S101, the CPU 71 acquires the latest relative distance D in the manner described above. In step S102, the CPU 71 determines whether the relative distance D is equal to or less than the first distance D1 (D ≤ D1). If the condition D ≤ D1 is not satisfied, the process proceeds to step S104, where the CPU 71 determines whether the relative distance D is greater than the first distance D1 and is equal to or less than the second distance D2 (D1 < D ≤ D2).

[0057] If the condition D1 < D ≤ D2 is not satisfied, the process proceeds to step S108, where the CPU 71 determines whether the relative distance D is greater than the second distance D2 and is equal to or less than the third distance D3 (D2 < D ≤ D3).

[0058] In step S104, if the CPU 71 determines that the condition D1 < D ≤ D2 is satisfied, indicating that the relative distance D is within an appropriate range, the process proceeds to step S105. In step S105, the CPU 71 determines whether the angular deviation Δθ in the relative orientation Bθ of the buoy 36 from the target relative orientation Tθ exceeds a predetermined angle θ0 (θ0 < Δθ). The value of the predetermined angle θ0 is stored in the memory 17.

[0059] If the CPU 71 determines that the condition θ0 < Δθ is not satisfied, indicating that both the relative distance D and the relative orientation Bθ are appropriate, the process proceeds to step S107. In step S107, the CPU 71 sets both the resistance plates (resistance plates 93L and 93R) to the second position (0°). In the case where step S107 is performed, it is considered that the wind has little effect on the hull 2, and that the hull 2 and the buoy 36 are flowing along with the tidal current, as illustrated in FIG. 5A. Therefore, the appropriate relative distance D is maintained by setting both the resistance plates to the second position.

[0060] On the other hand, if the condition θ0 < Δθ is satisfied, indicating that the relative orientation Bθ is inappropriate, the process proceeds to step S106, where the CPU 71 performs relative orientation deviation correction control. In the relative orientation deviation correction control, the CPU 71 sets one of the resistance plates (one of the resistance plates 93L and 93R) to the first position and the other (the other of the resistance plates 93L and 93R) to the second position. With respect to the control of the resistance plates 93L and 93R alone, the state corresponds to that illustrated in FIG. 5E.

[0061] Here, the resistance plate set to the first position (90°) is the one that generates a rotational moment on the hull 2 in a direction to correct the angular deviation Δθ. In the example of FIG. 5E, this corresponds to the resistance plate 93L. When the resistance plate 93L is in the first position, it is subjected to resistance from the tidal current, causing a counterclockwise turning force about the center of gravity G to be exerted on the hull 2. As a result, the angular deviation Δθ is reduced. Such control makes it easier to maintain the relative orientation Bθ of the buoy 36 close to the target relative orientation Tθ, thus maintaining a favorable fishing environment.

[0062] In step S108, if the CPU 71 determines that the condition D2 < D ≤ D3 is satisfied, indicating that the buoy 36 has deviated slightly to a farther side from the appropriate distance to the hull 2, the process proceeds to step S109. In step S109, the CPU 71 performs the same process as in step S105. In step S109, if the CPU 71 determines that the condition θ0 < Δθ is not satisfied, indicating that the relative distance D is inappropriate while the relative orientation Bθ is appropriate, the process proceeds to step S111.

[0063] In step S111, the CPU 71 sets both the resistance plates (resistance plates 93L and 93R) to the first position (90°). In the case where step S111 is performed, it is considered that the wind effect on the hull 2 is greater than that on the buoy 36, which is less affected by the wind, and that the hull 2 has moved away from the buoy 36, as illustrated in FIG. 5B. Therefore, by setting both the resistance plates to the first position, the extent to which the movement of the hull 2 depends on the tidal current can be increased. In effect, this acts as a brake on the hull 2 to resist the force exerted by the wind. As a result, the hull 2 and the buoy 36 or the fishing line are restrained from moving differently, making the fishing environment more comfortable. After step S111, the process proceeds to step S112.

[0064] In step S109, if the CPU 71 determines that the condition θ0 < Δθ is satisfied, this indicates that both the relative distance D and the relative orientation Bθ are inappropriate. In this case, correcting the relative orientation Bθ takes precedence over correcting the relative distance D, and the process proceeds to step S110, where the CPU 71 performs the same relative orientation deviation correction control as in step S106. With respect to the control of the resistance plates 93L and 93R alone, the state corresponds to that illustrated in FIG. 5E. Here, also, the resistance plate set to the first position (90°) is the one that generates a rotational moment on the hull 2 in a direction to correct the angular deviation Δθ. In the example of FIG. 5E, this corresponds to the resistance plate 93L. After step S110, the process proceeds to step S112.

[0065] In step S112, the CPU 71 determines whether the condition D2 < D ≤ D3 has continued to be satisfied for more than a predetermined time. The predetermined time begins counting when the determination in step S108 is Yes for the first time and is reset when step S113 is performed. If the CPU 71 determines that the condition D2 < D ≤ D3 has not remained satisfied for more than the predetermined time, the process proceeds to step S114.

[0066] On the other hand, if the CPU 71 determines that the condition D2 < D ≤ D3 has remained satisfied for more than the predetermined time, indicating that the relative distance D has remained in an inappropriate range for an extended period, the process proceeds to step S113. Additionally, if the CPU 71 determines that the condition D2 < D ≤ D3 is not satisfied in step S108, this means that D3 < D, indicating that the relative distance D has become too large, as illustrated in FIG. 5C, and the process proceeds to step S113.

[0067] In step S113, the CPU 71 performs propulsion device control. In the propulsion device control, the CPU 71 corrects the position of the hull 2 using the outboard motor 4 and the trolling motor 5. Specifically, the CPU 71 controls the outboard motor 4 and the trolling motor 5 such that the relative distance D satisfies D1 < D ≤ D2 and the relative orientation Bθ of the buoy 36 matches the target relative orientation Tθ (with the angular deviation Δθ being less than the predetermined angle θ0, preferably zero). The propulsion device control may also involve controlling the resistance plates 93L and 93R. This restores the positional relationship between the hull 2 and the buoy 36 or the fishing line to an appropriate state (see FIG. 5A).

[0068] In step S102, if the CPU 71 determines that the condition D ≤ D1 is satisfied, indicating that the hull 2 and the buoy 36 have become too close due to the effect of a crosswind or the like, as illustrated in FIG. 5D, the process proceeds to step S103. In step S103, the CPU 71 performs the same propulsion device control as in step S113.

[0069] After steps S103, S106, S107, and S113, the process proceeds to step S114. In step S114, the CPU 71 performs other processes, and the process then returns to step S101. The other processes include those performed according to user instructions, such as processes based on other operations, a mode-switching process, and a process for terminating this process.

[0070] According to this embodiment, the CPU 71, functioning as a control unit, controls the resistance plates 93 of the resistance plate units 90L and 90R based on the relative distance D. For example, in principle, the control is performed such that the hull 2 is located in a range that satisfies D1 < D ≤ D2, maintaining the hull 2 in an appropriate position. In addition, when the angular deviation Δθ exceeds the predetermined angle θ0, the relative orientation deviation correction control (S106, S110) is performed, maintaining the hull 2 in an appropriate orientation. As a result, even under windy conditions, the hull 2 can move primarily along with the tidal current without requiring manual operation of the resistance plates 93, while minimizing the use of propulsion devices to follow the buoy 36 and thereby improving quietness. This enables the provision of a comfortable drift fishing environment.

[0071] Moreover, if the relative distance D is either too short or too long, the propulsion device control (S103, S113) is performed. Furthermore, if the hull 2 remains in a range that satisfies D2 < D ≤ D3 for too long, the propulsion device control (S113) is also performed. This makes it possible to address cases where the position and orientation of the hull 2 cannot be corrected by controlling the resistance plates 93 alone.

[0072] Note that the resistance plate units 90L and 90R according to the embodiment are located at the stern. However it is sufficient the they are provided in a pair on the left and right sides as illustrated in FIGS. 6A and 6B.

[0073] FIGS. 6A and 6B are schematic diagrams illustrating modifications in the arrangement of the resistance plate units 90L and 90R. As illustrated in FIG. 6A, the resistance plate units 90L and 90R may be arranged on the left and right sides of the hull 2, respectively. Alternatively, as illustrated in FIG. 6B, the resistance plate units 90L and 90R may be arranged in a pair, one on the left side and one on the right side, near the bow.

[0074] The resistance plates 93 need only be provided as at least a pair, one on the left and one on the right, and there may be three or more of them.

[0075] In configuring the resistance plates 93 such that the magnitude of resistance they receive from the water in a predetermined direction differs when they are in the first position and when they are in the second position, it is not essential that the predetermined direction be the front-rear direction, and the direction may be arbitrary. The resistance plates 93 are an example of resistance members; they need not necessarily be in a plate shape and may have other shapes. It is also not essential that the resistance plates 93 at the first position and at the second position be perpendicular to each other.

[0076] Although this embodiment employs two motors, the outboard motor 4 and the trolling motor 5, as propulsion devices, it suffices if two or more propulsion devices are arranged to enable the hull 2 to turn. For example, one propulsion device may be provided at the bow, and two propulsion devices may be provided on either side of the stern. It is not essential that the propulsion devices each have an engine, and one or more may be electrically powered.

[0077] In addition, the resistance plates 93 have been described as having their positions adjustable in two steps. Alternatively, resistance plates are configured for continuous adjustment or adjustment in three or more steps. For example, a trim tab may be used. Furthermore, the resistance plates 93 need not necessarily be configured to pivot underwater; they may be of a type that moves between an above-water position and an underwater position, such as a protruding type. If the resistance plates 93 are configured for continuous adjustment or adjustment in three or more steps, the left and right resistance plates 93 can be controlled to protrude by different amounts in the relative orientation deviation correction control (S106, S110).

[0078] Incidentally, if the focus is solely on suppressing differing movements between the hull 2 and the buoy 36 or the fishing line through simple control to improve the drift fishing environment, it is not essential to include the relative orientation deviation correction control (S106, S110) or the propulsion device control (S103, S113). It is also not essential to include step S112, and the process may proceed directly to step S114 after steps S110 and S111.

Claims

1. A control device for a marine vessel (1) having a hull (2), comprising:

at least a pair of resistance members (93) configured to be arranged on the hull (2), one on left and one on right with regard to left-right direction of the marine vessel (1), each independently drivable and movable between a first position, where resistance received from water in a predetermined direction is adjusted to a first magnitude, and a second position, where the resistance is adjusted to zero or to a second magnitude smaller than the first magnitude;

an acquisition unit (70) that is configured to acquire a relative distance (D) between a buoy (36), which floats on the water in a free-drifting manner, and the hull (2); and

a control unit (71) that is configured to control the resistance members (93) based on the relative distance (D).

2. The control device according to claim 1, wherein the control unit (71) is configured to set both the resistance members (93) to the second position when the relative distance (D) is greater than a first distance (D1) and is equal to or less than a second distance (D2) that is greater than the first distance (D1).

3. The control device according to claim 2, wherein the acquisition unit (70) is configured to acquire a relative orientation (Bθ) of the buoy (36), the control unit (71) is configured to determine a deviation (Δθ) of the relative orientation (Bθ) of the buoy (36) with respect to the hull (2) from a pre-registered target relative orientation (Tθ) and configured to set one of the resistance members (93) to the first position and the other to the second position when the deviation (Δθ) of the relative orientation (Bθ) of the buoy (36) with respect to the hull (2) from the target relative orientation (Tθ) is more than a pre-registered predetermined angle (θ0), even if the relative distance (D) is greater than the first distance (D1) and is equal to or less than the second distance (D2).

4. The control device according to claim 2, wherein the control unit (71) is configured to set at least one of the resistance members (93) to the first position when the relative distance (D) is greater than the second distance (D2).

5. The control device according to claim 4, wherein the control unit (71) is configured to set both the resistance members (93) to the first position when the relative distance (D) is greater than the second distance (D2) and a relative orientation (Bθ) of the buoy (36) with respect to the hull (2) does not deviate from a target relative orientation (Tθ) by more than the predetermined angle (θ0).

6. The control device according to claim 4, wherein the control unit (71) configured to set one of the resistance members (93) to the first position and the other to the second position when the relative distance (D) is greater than the second distance (D2) and a relative orientation (Bθ) of the buoy (36) with respect to the hull (2) deviates from a target relative orientation (Tθ) by more than the predetermined angle (θ0).

7. The control device according to any one of claims 2 to 6, wherein the control unit (71) is configured to correct a position of the hull (2) using two or more propulsion devices (4, 5) of the marine vessel (1).

8. The control device according to claim 7, wherein the control unit (71) is configured to correct a position of the hull (2) using the propulsion devices (4, 5) when the relative distance (D) is equal to or less than the first distance (D1).

9. The control device according to claim 7 or 8, wherein the control unit (71) is configured to correct a position of the hull (2) using the propulsion devices (4, 5) when the relative distance (D) is greater than a third distance (D3) that is greater than the second distance (D2), preferably the control unit (71) is configured to correct the position of the hull (2) using the propulsion devices (4, 5) when a state where the relative distance (D) is greater than the second distance (D2) and is equal to or less than the third distance (D3) has continued for more than a predetermined time.

10. The control device according to any one of claims 1 to 9, wherein the buoy (36) is configured to be connected to the hull (2) by a connecting member (39).

11. The control device according to any one of claims 1 to 10, wherein the predetermined direction corresponds to a front-rear direction of the hull (2).

12. The control device according to claim 11, wherein the resistance members (93) are each configured to pivot about a pivot shaft parallel to an up-down direction,

the first position is a pivoted position where the resistance members (93) are perpendicular to the front-rear direction of the hull (2), and

the second position is a pivoted position where the resistance members (93) are parallel to the front-rear direction of the hull (2).

13. The control device according to any one of claims 1 to 12, wherein the buoy (36) is configured to output information indicating a position thereof, and
the acquisition unit (70) is configured to receive the information indicating the position of the buoy (36) and configured to acquire the relative distance (D) based on a position of the hull (2) and the information output from the buoy (36).

14. A marine vessel (1) having a hull (2) and comprising the control device according to any one of claims 1 to 13.

15. A method for controlling control device for a marine vessel (1) having a hull (2) and at least a pair of resistance members (93) arranged on the hull (2), one on left and one on right with regard to left-right direction of the marine vessel (1), each independently drivable and movable between a first position, where resistance received from water in a predetermined direction is adjusted to a first magnitude, and a second position, where the resistance is adjusted to zero or to a second magnitude smaller than the first magnitude, the method comprising:

acquiring a relative distance (D) between a buoy (36), which floats on the water in a free-drifting manner, and the hull (2); and

controlling the resistance members (93) based on the relative distance (D).

Drawing