Jet propulsion systems and jet-propelled boats

Abstract

The present invention provides a jet propulsion system and a jet-propelled boat that can reduce the burden on a person who has fallen overboard to re-board the vessel, and can also eliminate the feeling of confinement that a person feels inside the vessel after falling overboard. [Solution] This jet propulsion system 100 includes a jet propulsion mechanism 4 that generates thrust by ejecting a jet of water from the nozzle 44a, which is located at the stern 114 of the hull 110 and includes a nozzle 44 provided with a jet water jet nozzle 44a; a steering actuator 50 that rotates the nozzle 44 in the left-right direction to change the direction of the jet water jet from the nozzle 44a; and a control unit 8 that performs turning control to direct the stern 114 toward the person U who has fallen overboard from the hull 110 by ejecting a jet of water from the nozzle 44 and rotating the hull 110 with the steering actuator 50.

Description

Technical Field

[0001] This invention relates to a jet propulsion system and a jet propulsion boat equipped with a jet propulsion mechanism.

Background Art

[0002] Conventionally, a jet propulsion boat equipped with a jet propulsion mechanism has been known (for example, see Patent Document 1).

[0003] Patent Document 1 discloses a jet propulsion boat including a jet propulsion mechanism and a control unit that controls the drive of the jet propulsion mechanism to perform automatic steering of auto return. When a person falling into the water from the hull occurs, the control unit performs control to move the hull back to near the person falling into the water by auto return. Specifically, during auto return, the control unit first turns the hull so that the bow faces the person falling into the water, and then moves the hull forward to near the person falling into the water with the bow facing the person falling into the water.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the jet-propelled boat described in Patent Document 1, the hull moves forward with its bow facing the person who has fallen overboard, so if the person who has fallen overboard tries to re-board the boat, they need to go around to the stern of the hull, making re-boarding a burden for them. In addition, the fact that the bow of the hull is facing the person who has fallen overboard gives the person a feeling of pressure, as if the hull may be approaching them from the bow. Therefore, there is a need to reduce the burden on the person who has fallen overboard when re-boarding the hull, and to eliminate the feeling of pressure that the person feels from the hull after falling overboard.

[0006] This invention was made to solve the above-mentioned problems, and one of its objectives is to provide a jet propulsion system and a jet propulsion boat that can reduce the burden on a person who has fallen overboard to re-board the hull, and also eliminate the feeling of pressure that a person feels from the hull after falling overboard. [Means for solving the problem]

[0007] To achieve the above objective, the jet propulsion system in the first aspect of this invention includes a jet propulsion mechanism that generates thrust by ejecting a jet of water from a nozzle, which is located at the stern of the hull and includes a nozzle equipped with a jet of water nozzle; a steering actuator that rotates the nozzle in the left-right direction to change the direction of the jet of water from the nozzle; and a control unit that, in the event of a person falling overboard, performs turning control to point the stern towards the person overboard by ejecting a jet of water from the nozzle and rotating the hull using the steering actuator.

[0008] In the jet propulsion system according to the first aspect of this invention, as described above, when a person falls overboard, a control unit is provided that performs turning control by injecting a jet of water from a nozzle and rotating the hull using a steering actuator, thereby directing the stern towards the person who fell overboard. As a result, the stern of the hull can be directed towards the person who fell overboard, eliminating the need for the person to go around to the stern of the hull when re-boarding, thus reducing the burden on the person who fell overboard to re-board the hull. In addition, since the stern of the hull can be directed towards the person who fell overboard, the person who fell overboard will not be given the feeling of pressure that the hull may be approaching them from the bow, thus eliminating the feeling of pressure the person feels from the hull after falling overboard. In summary, the burden on the person who fell overboard to re-board the hull can be reduced, and the feeling of pressure the person feels from the hull after falling overboard can be eliminated.

[0009] In the jet propulsion system according to the first aspect described above, preferably, the system further comprises a communication unit provided on the hull and a location information device held by the person who has fallen overboard, which transmits the location information of the person who has fallen overboard to the communication unit, and the control unit, when a person falls overboard from the hull, performs turning control based on the location information to rotate the hull so that the stern faces the location information device. With this configuration, the location information device, which transmits the location information of the person who has fallen overboard to the communication unit, makes it easy for the control unit to identify the location of the person to whom the stern should be turned.

[0010] In this case, preferably, the position information device is a remote control device that receives an instruction to automatically move the hull to a waiting position near the person who has fallen overboard. When a person falls overboard, the control unit performs an auto-return to the waiting position based on the auto-return signal and position information received from the remote control device, and also performs turning control based on the position information to rotate the hull so that the stern faces the remote control device. With this configuration, not only can the stern of the hull be turned towards the person who has fallen overboard, but the hull can also be automatically moved to a waiting position near the person who has fallen overboard, thus further reducing the burden on the person who has fallen overboard to re-board the hull.

[0011] In a configuration where the above-mentioned position information device is a remote control device, preferably, the control unit performs turning control during auto-return, and then controls the hull to move in reverse to the standby position while pointing the stern towards the remote control device. With this configuration, the hull can be moved in reverse to reach the standby position near the person who has fallen overboard, so the hull will not be approaching the person who has fallen overboard from the bow, thus reducing the feeling of pressure the person who has fallen overboard may feel.

[0012] In a configuration in which the control unit controls the movement of the hull to the standby position by reversing, preferably, during auto-return, the control unit moves the hull forward, performs turning control to point the stern toward the remote control device at an intermediate position during auto-return, and then controls the movement of the hull to the standby position by reversing. With this configuration, the hull can be moved by forward, which has a relatively higher speed than reversing, up to an intermediate position during auto-return, so the time required for auto-return can be shortened compared to when the hull is moved only by reversing during auto-return.

[0013] In a configuration in which the control unit performs turning control at an intermediate position and then controls the hull to move to the standby position by reversing, it is preferable that the control unit is configured such that, during auto-return, the speed at which the hull moves in reverse is smaller than the speed at which the hull moves in forward. With this configuration, the hull can be moved to the standby position near the person who has fallen overboard using a relatively small speed of reverse movement, thereby further reducing the feeling of pressure the person who has fallen overboard feels in their vicinity.

[0014] In a configuration in which the control unit performs turning control at an intermediate position and then controls the hull to move to a standby position by reversing, preferably, when the control unit receives an auto-return signal from the remote control device, if the hull distance, which is the distance from the remote control device to the hull, is greater than a predetermined distance which is greater than the standby distance, which is the distance from the remote control device to the standby position, the control unit moves the hull forward to an intermediate position where it is at the predetermined distance, and then performs turning control to point the stern towards the remote control device. If the hull distance is less than or equal to the predetermined distance when the auto-return signal is received from the remote control device, the control unit is configured to perform turning control immediately. With this configuration, when the hull is relatively close to a person who has fallen overboard, such that the hull distance is less than or equal to the predetermined distance when the auto-return is initiated, it is possible to avoid the hull moving forward towards the person who has fallen overboard during the auto-return.

[0015] In a configuration where the control unit moves the vessel forward to an intermediate position and then performs turning control when the hull distance is greater than a predetermined distance, and immediately performs turning control when the hull distance is less than or equal to the predetermined distance, the predetermined distance is preferably set to a predetermined distance of 5m to 15m. With this configuration, the forward movement of the vessel can be stopped and the vessel can be switched to reverse at a position relatively far from the person who has fallen into the water, between 5m and 15m away.

[0016] In a configuration where the control unit moves the vessel forward to an intermediate position and then performs turning control when the hull distance is greater than a predetermined distance, and the control unit immediately performs turning control when the hull distance is less than or equal to the predetermined distance, the waiting distance is preferably set to a predetermined distance of 1m to 3m. With this configuration, in auto-return, it is possible to avoid the vessel moving closer to the person who has fallen overboard than the predetermined waiting distance of 1m to 3m.

[0017] In a configuration where the above-mentioned position information device is a remote control device, preferably, the control unit is configured to perform an automatic return to the ship's standby position along a straight line connecting the remote control device and the ship's hull. With this configuration, it is possible to avoid causing anxiety to the person who has fallen overboard as the ship moves away from them during the automatic return.

[0018] In the jet propulsion system according to the first aspect described above, preferably, the system further comprises a jet drive source that drives a jet propulsion mechanism to eject a jet of water, and a lanyard, one end of which is held by the operator and the other end of which is detachably connected to the hull, and the control unit is configured to maintain the drive state of the jet drive source and stop the movement of the hull when the lanyard is detached from the hull. With this configuration, the drive state of the jet drive source can be maintained even when the lanyard is detached from the hull. That is, it is possible to maintain a state in which turning control can be performed by the jet drive source. In addition, since the movement of the hull can be stopped, it is possible to prevent the distance from the person who has fallen overboard to the hull from increasing.

[0019] In the jet propulsion system according to the first phase described above, preferably, a reboarding step is provided at the stern of the hull for a person who has fallen overboard to place their feet on when boarding, and the control unit performs turning control to rotate the hull so that the stern with the reboarding step faces the person who has fallen overboard when a person has fallen overboard. With this configuration, the burden on the person who has fallen overboard to re-board the hull can be further reduced by the reboarding step.

[0020] A jet-propelled boat in the second aspect of this invention comprises a hull, a jet propulsion mechanism located at the stern of the hull and including a nozzle with a jet of water ejection port, which generates thrust by ejecting a jet of water from the nozzle's ejection port, a steering actuator that rotates the nozzle in the left-right direction to change the direction of the jet of water ejection from the nozzle's ejection port, and a control unit that, in the event of a person falling overboard, performs turning control to point the stern towards the person overboard by ejecting a jet of water from the nozzle and rotating the hull using the steering actuator.

[0021] In the jet-propelled boat according to the second aspect of this invention, as described above, when a person falls overboard, a control unit is provided that performs turning control by injecting a jet of water from a nozzle and rotating the hull using a steering actuator, thereby directing the stern towards the person who fell overboard. As a result, the stern of the hull can be directed towards the person who fell overboard, eliminating the need to go around to the stern of the hull when re-boarding, thus reducing the burden on the person who fell overboard to re-board the hull. In addition, since the stern of the hull can be directed towards the person who fell overboard, the feeling of pressure that the hull might be approaching them from the bow is eliminated, thus removing the feeling of pressure the person feels from the hull after falling overboard. Thus, it is possible to provide a jet-propelled boat that can reduce the burden on the person who fell overboard to re-board the hull and remove the feeling of pressure the person feels from the hull after falling overboard.

[0022] In the jet-propelled boat according to the second aspect described above, preferably, a communication unit is further provided that communicates with a location information device, which is installed on the hull, is held by the person who has fallen overboard, and transmits the location information of the person who has fallen overboard. The control unit, when a person falls overboard from the hull, performs turning control based on the location information to rotate the hull so that the stern faces the location information device. With this configuration, the location information device, which transmits the location information of the person who has fallen overboard to the communication unit, makes it easy for the control unit to identify the location of the person to whom the stern should be turned.

[0023] In this case, preferably, the position information device is a remote control device that receives an auto-return instruction to automatically move the hull to a standby position near the person who has fallen overboard. When a person falls overboard from the hull, the control unit performs an auto-return to the standby position based on the auto-return signal instructing the auto-return received from the remote control device and the position information, and performs turning control to turn the hull to face the stern towards the remote control device based on the position information. With such a configuration, not only can the stern of the hull be directed towards the person who has fallen overboard, but the hull can also be automatically moved to the standby position near the person who has fallen overboard, so that the burden on the person who has fallen overboard to re-board the hull can be further reduced.

[0024] In the configuration where the above position information device is a remote control device, preferably, during auto-return, the control unit performs control to move the hull to the standby position by reverse movement while turning the stern towards the remote control device after performing turning control. With such a configuration, the movement to reach the standby position near the person who has fallen overboard can be performed by reverse movement, so that in the vicinity of the person who has fallen overboard, the hull will not approach the person who has fallen overboard from the bow side, and thus the sense of oppression felt by the person who has fallen overboard can be reduced.

[0025] In the configuration where the above control unit performs control to move the hull to the standby position by reverse movement, preferably, during auto-return, the control unit moves the hull forward, performs turning control to turn the stern towards the remote control device at an intermediate position during auto-return, and then performs control to move the hull to the standby position by reverse movement. With such a configuration, until the intermediate position during auto-return, the hull can be moved forward at a relatively higher speed than reverse movement, so that the time required for auto-return can be shortened compared to the case where the hull is moved only by reverse movement during auto-return.

[0026] In a configuration where the control unit performs turning control at an intermediate position and then controls the hull to move to the standby position by reverse movement, preferably, the control unit is configured such that, during auto return, the speed at which the hull is moved by reverse movement is made smaller than the speed at which the hull is moved by forward movement. With this configuration, the movement to reach the standby position near the person who has fallen into the water can be performed by reverse movement at a relatively low speed, so that the sense of oppression felt by the person who has fallen into the water can be further reduced in the vicinity of the person who has fallen into the water.

[0027] In a configuration where the control unit performs turning control at an intermediate position and then controls the hull to move to the standby position by reverse movement, preferably, when the control unit receives an auto return signal from the remote control device, if the hull distance, which is the distance from the remote control device to the hull, is greater than a predetermined distance that is greater than the standby distance, which is the distance from the remote control device to the standby position, the hull is moved forward to an intermediate position at a predetermined distance and then turning control is performed to turn the stern toward the remote control device. When the control unit receives an auto return signal from the remote control device and the hull distance is less than or equal to the predetermined distance, it is configured to immediately perform turning control. With this configuration, when the hull is relatively close to the person who has fallen into the water such that the hull distance becomes less than or equal to the predetermined distance at the start of auto return, it is possible to avoid the hull approaching the person who has fallen into the water by forward movement during auto return.

[0028] In a configuration where the control unit performs turning control after moving forward to an intermediate position when the hull distance is greater than the predetermined distance and immediately performs turning control when the hull distance is less than or equal to the predetermined distance, preferably, the predetermined distance is set to a predetermined distance of 5 m or more and 15 m or less. With this configuration, it is possible to end the forward movement of the hull and switch to reverse movement at a position relatively far from the person who has fallen into the water of 5 m or more and 15 m or less.

Advantages of the Invention

[0029] According to the present invention, as described above, it is possible to provide a jet propulsion system and a jet propulsion boat that can reduce the burden on a person who has fallen overboard to re-board the hull, and also eliminate the feeling of pressure that a person feels from the hull after falling overboard. [Brief explanation of the drawing]

[0030] [Figure 1] This is a side view showing a jet-propelled boat equipped with a jet propulsion system according to an embodiment. [Figure 2] This is a magnified side view showing a portion of a jet-powered boat equipped with a jet propulsion system according to an embodiment. [Figure 3] This is a block diagram of a jet propulsion system according to an embodiment. [Figure 4] This figure shows a jet-propelled boat according to an embodiment, and a remote control device that communicates wirelessly with the jet-propelled boat. [Figure 5] This figure shows the display screen of a remote control device for a jet propulsion system according to an embodiment. [Figure 6] This is a schematic plan view illustrating the lateral rotation of the nozzle of the jet propulsion mechanism of a jet propulsion system according to an embodiment. [Figure 7] This is a schematic side view illustrating the vertical rotation (trim) of the nozzle of a jet propulsion mechanism according to an embodiment. [Figure 8] This is a schematic side view illustrating the vertical rotation of the reverse bucket of a jet propulsion mechanism according to an embodiment. [Figure 9] This is a magnified view of part A in Figure 2. [Figure 10] This diagram shows the operating section according to the embodiment, viewed from the rear. [Figure 11] This is a plan view illustrating the movement of the hull in auto-return and turning control according to the embodiment. [Figure 12] This is a flowchart of the control process for auto-return and steering control according to the embodiment. [Modes for carrying out the invention]

[0031] Hereinafter, one embodiment of the present invention will be described based on the drawings.

[0032] (Embodiment) (Configuration of a jet-powered boat) A jet-propelled boat 100 according to one embodiment of the present invention will be described with reference to Figures 1 to 12.

[0033] The jet-powered boat 100 shown in Figures 1 and 2 is a personal watercraft configured to carry a relatively small number of people. The jet-powered boat 100 is a so-called jet ski that glides across the water's surface. The jet-powered boat 100 comprises a hull 110 and a jet propulsion system 120 mounted on the hull 110. The hull 110 includes a hull 111 that forms the bottom of the boat, a deck 112 located above the hull 111, and seats 113 located in the center of the left and right sides of the deck 112. In addition, a reboarding step 116 is provided at the stern 114 of the hull 110 for people on the water to place their feet on when boarding the hull 110. The reboarding step 116 is configured to be retractable from the use position shown in Figure 2 to a predetermined storage position (not shown).

[0034] (Configuration of a jet propulsion system) As shown in Figure 3, the jet propulsion system 120 comprises a communication unit 1, a remote control device 2, a jet drive source 3, a jet propulsion mechanism 4 including a nozzle 44 (see Figure 1) for ejecting a jet of water, an actuator 5 for changing the direction of the jet of water, an operating unit 6, a lanyard 7, and a control unit 8. The actuator 5 includes a steering actuator 50 and a trim actuator 55 for driving the nozzle 44, and a reverse actuator 56 for driving the reverse bucket 45. The remote control device 2 is an example of the "location information device" in the claims.

[0035] In each figure, the longitudinal direction of the jet-propelled boat 100 is indicated by the X direction, with the forward direction being indicated by the X1 direction (FRD) and the reverse direction being indicated by the X2 direction (BWD). In each figure, the lateral direction of the jet-propelled boat 100 is indicated by the Y direction. In each figure, the vertical direction is indicated by the Z direction, with the upward direction being indicated by the Z1 direction and the downward direction being indicated by the Z2 direction.

[0036] The jet propulsion system 120 (control unit 8) of this embodiment is configured to perform steering control so that when a person U (see Figure 11) falls overboard from the hull 110, a jet of water is injected from the nozzle 44 and the steering actuator 50 rotates the hull 110, thereby directing the stern 114 toward the person U. In other words, the jet propulsion system 120 (control unit 8) is configured to perform steering control so that when a person U falls overboard from the hull 110, the hull 110 rotates and the stern 114, which is equipped with a reboarding step 116, is directed toward the person U. Further details will be described later.

[0037] (Configuration of the communication unit and remote control device) The communication unit 1 is located on the hull 110. The communication unit 1 is configured to establish wireless communication with the remote control device 2. For example, the communication unit 1 is configured to establish wireless communication with the remote control device 2 using Bluetooth®. However, the communication unit is not limited to Bluetooth and may be a wireless communication unit using other communication standards such as Wi-Fi®. As preparation before sailing by the jet-propelled boat 100, the operator establishes wireless communication with the communication unit 1 (see Figure 4).

[0038] The remote control device 2 is held by the operator of the jet-powered boat 100. For example, the remote control device 2 is a smartphone. However, the remote control device is not limited to a smartphone; it may also be a dedicated communication device for wireless communication with the jet-powered boat, or a tablet device. The remote control device 2 has a dedicated application installed for establishing communication with the jet-powered boat 100.

[0039] In this scenario, if the operator of the jet-powered boat 100 falls overboard, the remote control device 2 will be held by the person who fell overboard, U (see Figure 11). The remote control device 2 is configured to acquire its own location information I1 (see Figure 3). Specifically, the remote control device 2 has a GPS receiver. The jet-powered boat 100 also has a GPS receiver 9. The remote control device 2 is configured to transmit the location information I1 of the person who fell overboard, U (remote control device 2), to the communication unit 1 of the jet-powered boat 100.

[0040] The remote control device 2 is configured to receive an auto-return command, which automatically moves the hull 110 to a waiting position P1 (see Figure 11) near the person who fell overboard U. When the auto-return is executed, the person who fell overboard U can easily re-board the jet-powered boat 100.

[0041] The remote control device 2 is a device that instructs the movement of the hull 110 via wireless communication with the hull 110. There are two modes in the wireless operation mode in which the movement of the hull 110 is instructed by the remote control device 2. The wireless operation mode includes the remote operation mode and the automatic movement mode.

[0042] The remote control mode is a mode in which the hull 110 is operated remotely using the remote control device 2. The remote control mode is activated by selecting "Remote Control" on the mode switching button 21 in the upper left corner of the display screen 20 (see Figure 5) of the dedicated application for the remote control device 2. If "Normal" is selected on the mode switching button 21, the mode switches to the normal mode in which the operator operates the steering control unit 60 to steer the boat themselves. In remote control mode, the jet-propelled boat 100 is moved freely by remote control using the hull operation buttons 22 on the display screen 20 (forward (F) button, reverse (R) button, and left and right turn buttons in the center of the screen, etc.).

[0043] The automatic movement mode is a mode in which the hull 110 is moved automatically by issuing instructions to the hull 110 from a remote control device 2. The automatic movement mode includes modes such as auto-return, fixed-point holding, and launching support. The automatic movement mode is switched by selecting "auto-return," "fixed-point holding," or "launching support" using the mode switching button 21 in the upper left corner of the display screen 20 of the remote control device 2 (see Figure 5).

[0044] Furthermore, if the "Auto Return" automatic movement mode is selected on the display screen 20 (see Figure 5) of the remote control device 2, an Auto Return Start button 23 (see Figure 5) will be displayed at the bottom of the display screen 20. When the Auto Return Start button 23 is operated, an Auto Return signal I2 (see Figure 3), which will be described later, is transmitted to the hull 110 to initiate the Auto Return.

[0045] (Configuration of the jet power source) As shown in Figure 1, the jet drive source 3 includes an engine 30, a crankshaft 31, and a coupling 32. The engine 30 is a multi-cylinder internal combustion engine. The crankshaft 31 is an output shaft for outputting torque generated in the engine 30. The crankshaft 31 extends rearward from the engine 30. The coupling 32 is provided at the rear end of the crankshaft 31 and connects and fixes the crankshaft 31 to the impeller shaft 41 of the jet propulsion mechanism 4.

[0046] (Configuration of the jet propulsion system) As shown in Figure 2, the jet propulsion mechanism 4 is configured to generate thrust by ejecting a jet of water from the nozzle 44a of the nozzle 44. The jet propulsion mechanism 4 comprises a water channel 40, an impeller shaft 41, an impeller 42, a nozzle 43 fixed to the rear end of the water channel 40, a nozzle 44 drivably mounted relative to the nozzle 43, and a reverse bucket (reverse gate) 45.

[0047] The waterway 40 extends from the lower part of the hull 110 toward the stern 114. Water is drawn into the waterway 40 from the intake port 40a at the lower part of the hull 110. An impeller shaft 41 extending toward the rear is located in the waterway 40. The impeller 42 is fixed to the impeller shaft 41. The impeller 42 rotates integrally with the impeller shaft 41, generating a flow toward the rear. The impeller shaft 41 is connected to the crankshaft 31 via a coupling 32. Therefore, the rotational speed of the impeller 42 increases or decreases in accordance with the increase or decrease in the rotational speed of the engine 30.

[0048] The nozzle 43 shown in Figure 6 has the function of spraying water flowing through the waterway 40 toward the rear nozzle 44. The nozzle 44 is attached to the nozzle 43 from the rear. The nozzle 44 is located at the stern 114 of the hull 110. The nozzle 44 is provided with a jet water flow nozzle 44a. The nozzle 44 has the function of a deflector that changes the direction of the jet water flow sprayed from the nozzle 44a. In detail, the nozzle 44 is attached to the nozzle 43 so that it can rotate left and right around the central axis C1 of the vertical central axis 46 that extends in the vertical direction (the steering position can be adjusted around the vertical central axis 46). The central axis C1 is located at the left-right center of the nozzle 44. The nozzle 44 is rotated left and right by the steering actuator 50.

[0049] The nozzle 44 shown in Figure 7 is attached to the nozzle 43 so as to be able to rotate vertically around the central axis C2 of the left-right central axis 47 that extends horizontally (the trim position can be adjusted around the left-right central axis 47). The central axis C2 is located at the vertical center of the nozzle 44. The nozzle 44 is rotated vertically by the trim actuator 55. In this way, the rotation of the nozzle 44 in the vertical, horizontal, and vertical directions changes the direction of the jet stream ejected from the nozzle opening 44a.

[0050] The reverse bucket 45 shown in Figure 8 is configured to change the direction of the jet stream in the forward and backward directions. The reverse bucket 45 rotates between an upper position above the nozzle 44 and a rear position above the nozzle 44, and when it moves to the rear position above the nozzle 44, it covers the nozzle 44a from the rear, thereby guiding the jet stream forward and changing the direction of the jet stream forward. The reverse bucket 45 is configured to rotate vertically around the central axis C3 of the left and right central axes 48 that extend in the left and right directions. The reverse bucket 45 is rotated vertically by a reverse actuator 56. Depending on the position of the reverse bucket 45, the jet propulsion boat 100 can switch between a forward state, a reverse state, and a neutral state in which the forward thrust and reverse thrust are approximately equal. The jet-propelled boat 100 is in a reverse or neutral position when the reverse bucket 45 covers the nozzle 44a from the rear, and in a forward position when the reverse bucket 45 does not cover the nozzle 44a from the rear. The reverse bucket 45 is provided with substantially cylindrical ejection openings 45a on both the left and right sides, having a central axis that points diagonally forward to the right of the hull 110.

[0051] (Configuration of the steering actuator) Referring to Figures 2 and 9, the steering actuator 50 includes an electric motor 51 as a drive source, a transmission gear 52 that transmits the driving force of the electric motor 51 and the steering control unit 60 to the nozzle 44, a nozzle-side steering cable 53, and a control unit-side steering cable 54. In wireless steering mode, the steering actuator 50 is configured to rotate the nozzle 44 in the left-right direction using the driving force of the electric motor 51, thereby changing the direction of the jet water flow from the injection port 44a in the left-right direction. The steering actuator 50 can rotate the nozzle 44 in the left-right direction even when a jet water flow is not being injected.

[0052] The electric motor 51 is equipped with a motor shaft 51a, a transmission shaft 51b, and a clutch 51c that switches the connection state between the motor shaft 51a and the transmission shaft 51b. Note that jet-propelled boats do not need to have a clutch. A bevel gear 51d is provided on the side of the transmission shaft 51b opposite to the clutch 51c.

[0053] The transmission gear 52 includes a first gear 52a having a bevel gear portion 521 and a pinion portion 522 that mesh with the bevel gear 51d, and a second gear 52b consisting of a rack that meshes with the pinion portion 522. The nozzle-side steering cable 53 has one end connected to the transmission gear 52 and the nozzle 44, respectively, and is configured to push and pull the nozzle 44. The control unit-side steering cable 54 has one end connected to the transmission gear 52 and the steering control unit 60, respectively, and is configured to push and pull the nozzle 44 via the second gear 52b and the nozzle-side steering cable 53. The nozzle-side steering cable 53 and the control unit-side steering cable 54 are configured as push-pull cables. The control unit-side steering cable 54 is configured to push and pull the steering control unit 60 when the electric motor 51 is driven. That is, when the electric motor 51 is driven, the steering control unit 60 will operate even without operation of the steering control unit 60 by the operator. The nozzle-side steering cable 53 is connected to the steering cable connection portion 44b of the nozzle 44. The nozzle 44 rotates left and right as it is pushed and pulled by the nozzle-side steering cable 53.

[0054] (Trim actuator configuration) The trim actuator 55 shown in Figure 7 includes an electric motor (not shown) as a drive source and a trim cable 55a that transmits the driving force of the electric motor to the nozzle 44. The trim actuator 55 is configured to rotate the nozzle 44 vertically using the driving force of the electric motor, thereby changing the direction of the water jet. The trim actuator 55 can rotate the nozzle 44 vertically even when the water jet is not being sprayed. The trim cable 55a is connected to the trim cable connection part 44c of the nozzle 44. The trim cable 55a is made of a push-pull cable. The trim actuator 55 is driven based on operations on the trim operation part 62.

[0055] (Configuration of the reverse actuator) The reverse actuator 56 shown in Figure 8 includes an electric motor (not shown) as a drive source and a reverse cable 56a that transmits the driving force of the electric motor to the reverse bucket 45. The reverse actuator 56 is configured to rotate the reverse bucket 45 vertically using the driving force of the electric motor, thereby changing the direction of the water jet in the front-rear direction. The reverse cable 56a is connected to the reverse cable connection part 45b of the reverse bucket 45. The reverse cable 56a is made of a push-pull cable.

[0056] (Configuration of the control panel) As shown in Figure 10, the operating unit 6 includes a steering operating unit 60, a throttle lever 61, and a trim operating unit 62.

[0057] The steering control section 60 consists of a pair of bar-shaped grip sections provided on the left and right sides of the hull 110. The driving force input from the operator to the steering control section 60 is transmitted to the nozzle 44 via the steering cable 54 on the control section side, the transmission gear 52, and the steering cable 53 on the nozzle side, as shown in Figure 9. As a result, the nozzle 44 rotates in the left and right directions.

[0058] The throttle lever 61 shown in Figure 10 is configured to increase or decrease the rotational speed of the impeller 42 (the opening degree of the throttle valve of the engine 30) according to the amount of operation. The harder the throttle lever 61 is squeezed, the greater the amount of operation, and therefore the stronger the jet of water. The throttle lever 61 is equipped with a lever position sensor 63 that detects the amount of operation of the throttle lever.

[0059] In detail, the throttle lever 61 has a forward throttle lever 61a for moving the hull 110 forward and a reverse throttle lever 61b for moving the hull 110 backward. The forward throttle lever 61a is located along the right-side steering control unit 60. The reverse throttle lever 61b is located along the left-side steering control unit 60. The lever position sensor 63 also has a forward lever position sensor 63a for detecting the amount of movement of the forward throttle lever 61a and a reverse lever position sensor 63b for detecting the amount of movement of the reverse throttle lever 61b.

[0060] The trim operation unit 62 has a trim-up button and a trim-down button. When the trim-up button is pressed, the trim actuator 55 rotates the nozzle 44 upward. When the trim-down button is pressed, the trim actuator 55 rotates the nozzle 44 downward.

[0061] (Lanyard configuration) Lanyard 7 is configured to detect if the operator has fallen into the water. Lanyard 7 has a switch section 70 provided on the hull 110, a plate section 71 that is detachably connected to the switch section 70 on the hull 110, and a string-like cord section 72. One end of the cord section 72 is held by the operator, and the other end is connected to the plate section 71. If the operator falls into the water, the operator will pull on the cord section 72, causing the plate section 71 to detach from the switch section 70. The control unit 8 is configured to maintain the drive state of the jet drive source 3 (see Figure 1) and stop the movement of the hull 110 when the plate section 71 is detached from the switch section 70 on the hull 110.

[0062] In other words, the jet-powered boat 100 will not emergency stop the engine 30 (see Figure 1) if the plate portion 71 of the lanyard 7 comes loose. Furthermore, the jet-powered boat 100 will stop moving while the engine 30 is running if the plate portion 71 of the lanyard 7 comes loose. By keeping the engine 30 running when the plate portion 71 of the lanyard 7 comes loose, the jet-powered boat 100 will be able to respond to any subsequent requests for auto-return from the person who has fallen overboard U. Note that the lanyard of a typical jet-powered boat is used as an emergency stop switch for the engine. Specifically, in a typical jet-powered boat lanyard, the engine is emergency stopped if the plate portion comes loose from the switch portion. In this case, the engine cannot be restarted unless the plate portion is reinserted into the switch portion.

[0063] (Configuration of the control unit) As an example, the control unit 8 shown in Figure 1 includes an ECU (Engine Control Unit), an SCU (Shift Control Unit) that performs shift switching control, an RCU (Remote Control Unit) that performs ship handling control in wireless operation mode, and a steering actuator control device that performs control to drive the steering actuator 50. The control unit may also be configured as a single control device. The control unit 8 is a computer that includes a CPU, ROM, RAM, etc.

[0064] As described above, the control unit 8 is configured to perform steering control so that when a person U falls overboard from the hull 110, it sprays a jet of water from the nozzle 44 and rotates the hull 110 using the steering actuator 50, thereby directing the stern 114 toward the person U who fell overboard.

[0065] When a person U falls overboard from the hull 110, the control unit 8 performs turning control to rotate the hull 110 and point the stern 114 toward the remote control device 2, based on the position information I1 (see Figure 3). When a person U falls overboard from the hull 110, the control unit 8 performs an auto-return to the standby position P1 based on the auto-return signal I2 (see Figure 3) and position information I1 received from the remote control device 2, and also performs turning control to rotate the hull 110 and point the stern 114 toward the remote control device 2 (person U). The control unit 8 performs this turning control while the auto-return is being executed. Specifically, the control unit 8 performs the turning control during the auto-return is being executed, or immediately after the start of the auto-return.

[0066] During auto-return, the control unit 8 performs turning control and then controls the hull 110 to the standby position P1 by moving it in reverse while pointing the stern 114 toward the remote control device 2. More specifically, during auto-return, the control unit 8 moves the hull 110 forward, performs turning control at an intermediate position P2 during auto-return so that the stern 114 is pointing toward the remote control device 2, and then controls the hull 110 to the standby position P1 by moving it in reverse. The control unit 8 is configured so that the speed at which the hull 110 moves in reverse is less than the speed at which the hull 110 moves in forward during auto-return.

[0067] More specifically, when the control unit 8 receives an auto-return signal I2 from the remote control device 2, if the hull distance D0, which is the distance from the remote control device 2 to the hull 110, is greater than a predetermined distance D2 which is greater than the standby distance D1, which is the distance from the remote control device 2 to the standby position P1, the control unit 8 moves the hull 110 forward to an intermediate position P2 where the distance is the predetermined distance D2, and then performs turning control to point the stern 114 towards the remote control device 2. The control unit 8 is configured to perform turning control immediately (immediately after the start of auto-return) when it receives the auto-return signal I2 from the remote control device 2 and the hull distance D0 is less than or equal to the predetermined distance D2. Furthermore, the control unit 8 is configured to perform auto-return of the hull 110 to the standby distance D1 along a straight path R connecting the remote control device 2 and the hull 110.

[0068] For example, the predetermined distance D2 is set to a predetermined distance of 5m to 15m. For a specific example, the predetermined distance D2 is 10m. Also, for example, the standby distance D1 is set to a predetermined distance of 1m to 3m. For a specific example, the standby distance D1 is 1.5m.

[0069] (Flowchart of control processing for auto-return and steering control) Referring to Figure 11, the control process flow for the auto-return and turning control shown in Figure 12 will be described. The auto-return and turning control is performed by the control unit 8. The flow described below starts from a state in which a person U has fallen overboard from the hull 110, the jet drive source 3 is maintained in operation by the lanyard 7, and the movement of the hull 110 has stopped.

[0070] In step S1, it is determined whether or not an auto-return instruction has been received. That is, it is determined whether or not an auto-return signal I2 instructing the start of auto-return has been received from the remote control device 2. If it is determined that an auto-return instruction has been received, the process proceeds to step S2; if it is determined that no auto-return instruction has been received, step S1 is repeated.

[0071] In step S2, the remote control device 2 obtains location information I1 of the person who fell into the water U. Then, the process proceeds to step S3.

[0072] In step S3, it is determined whether the hull distance D0 is greater than a predetermined distance D2. If it is determined that the hull distance D0 is greater than the predetermined distance D2, the process proceeds to step S4. If it is determined that the hull distance D0 is less than or equal to the predetermined distance D2, the process proceeds to step S6.

[0073] In step S4, the hull 110 is turned (in place) so that the bow 115 is pointed towards the person U who has fallen overboard. In this case, as a result of the turn, the remote control device 2 will be positioned on the left-right central axis of the hull 110. At this time, the turn can be either left or right, but it is preferable to turn in the direction that reduces the turning angle. Then proceed to step S5.

[0074] In step S5, the ship 110 moves forward in a straight line to an intermediate position P2. That is, it moves to a position where the ship distance D0 is equal to a predetermined distance D2. During this time, the ship 110 moves along a straight path R. After that, the process proceeds to step S6.

[0075] In step S6, turning control is performed. That is, in step S6, the hull 110 is turned (in place) so that the stern 114 is pointed towards the person U who has fallen overboard. In this case, as a result of the turn, the remote control device 2 is positioned on the left-right central axis of the hull 110. The angle of the turn of the hull 110 in step S6 is approximately 180 degrees. The process then proceeds to step S7.

[0076] In step S7, the hull 110 moves in reverse to a waiting position P1 near the person who fell overboard U. At this time, the reverse speed is less than the forward speed during auto-return. Also, at this time, the hull 110 moves along a straight path R. Once the hull 110 has reached the waiting position P1, its movement stops and it is held at the waiting position P1. After that, it proceeds to the end.

[0077] (Effects of the embodiment) In this embodiment, the following effects can be obtained.

[0078] In this embodiment, as described above, when a person U falls overboard from the hull 110, a control unit 8 is provided that performs turning control to direct the stern 114 toward the person U by injecting a jet of water from the nozzle 44 and rotating the hull 110 with the steering actuator 50. This allows the stern 114 of the hull 110 to be directed toward the person U after they fall overboard, eliminating the need for the person U to go around to the stern 114 of the hull 110 when re-boarding, thus reducing the burden on the person U when re-boarding the hull 110. Furthermore, since the stern 114 of the hull 110 can be directed toward the person U after they fall overboard, the feeling of pressure that the hull 110 might be approaching them from the bow 115 side is eliminated, thus removing the feeling of pressure that the person U feels from the hull 110 after they fall overboard. As a result, the burden on the person who fell overboard U to re-board the hull 110 can be reduced, and the feeling of confinement that the person who fell overboard U feels from the hull 110 after falling overboard can be eliminated.

[0079] In this embodiment, as described above, the vessel further includes a communication unit 1 provided on the hull 110, and a location information device (remote control device 2) held by the person who has fallen overboard U, which transmits the location information I1 of the person who has fallen overboard U to the communication unit 1. When a person who has fallen overboard U occurs from the hull 110, the control unit 8 performs turning control to rotate the hull 110 and point the stern 114 toward the location information device based on the location information I1. As a result, the location information device, which transmits the location information I1 of the person who has fallen overboard U to the communication unit 1, allows the control unit 8 to easily identify the location of the person who has fallen overboard U to which the stern 114 should be pointed.

[0080] In this embodiment, as described above, the position information device is a remote control device 2 that receives an instruction to automatically move the hull 110 to a waiting position P1 near the person who fell overboard U. When a person who fell overboard U occurs from the hull 110, the control unit 8 performs an auto-return to the waiting position P1 based on the auto-return signal I2 and position information I1 received from the remote control device 2, and also performs turning control based on the position information I1 to rotate the hull 110 so that the stern 114 faces the remote control device 2. This not only turns the stern 114 of the hull 110 toward the person who fell overboard U, but also automatically moves the hull 110 to the waiting position P1 near the person who fell overboard U, thereby further reducing the burden on the person who fell overboard U to re-board the hull 110.

[0081] In this embodiment, as described above, during auto-return, the control unit 8 performs turning control and then controls the hull 110 to the standby position P1 by reversing while pointing the stern 114 towards the remote control device 2. As a result, the movement of the hull 110 to the standby position P1 near the person who fell overboard U can be performed by reversing, so the hull 110 does not come towards the person who fell overboard U from the bow 115 side in the vicinity of the person who fell overboard U, thereby reducing the feeling of pressure felt by the person who fell overboard U.

[0082] In this embodiment, as described above, during auto-return, the control unit 8 moves the hull 110 forward, performs turning control to point the stern 114 towards the remote control device 2 at the intermediate auto-return position P2, and then controls the hull 110 to the standby position P1 in reverse. As a result, the hull 110 can be moved forward, which is at a relatively higher speed than reverse, up to the intermediate auto-return position P2, thus shortening the time required for auto-return compared to when the hull is moved only in reverse during auto-return.

[0083] In this embodiment, as described above, the control unit 8 is configured to move the hull 110 in reverse at a speed less than the speed at which it moves in forward during auto-return. This allows the hull 110 to reach the waiting position P1 near the person who fell overboard U by moving it in reverse at a relatively low speed, thereby reducing the feeling of pressure felt by the person who fell overboard U in their vicinity.

[0084] In this embodiment, as described above, when the control unit 8 receives an auto-return signal I2 from the remote control device 2, if the hull distance D0, which is the distance from the remote control device 2 to the hull 110, is greater than a predetermined distance D2 which is greater than the standby distance D1, which is the distance from the remote control device 2 to the standby position P1, the control unit 8 moves the hull 110 forward to an intermediate position P2 where the distance is the predetermined distance D2, and then performs turning control to point the stern 114 towards the remote control device 2. If the hull distance D0 is less than or equal to the predetermined distance D2 when the auto-return signal I2 is received from the remote control device 2, the control unit 8 is configured to immediately perform turning control. This makes it possible to avoid the hull 110 moving forward towards the person who has fallen overboard U when the auto-return is initiated, in cases where the hull distance D0 is less than or equal to the predetermined distance D2 when the hull 110 is relatively close to the person who has fallen overboard U.

[0085] In this embodiment, as described above, the predetermined distance D2 is set to a predetermined distance of 5m to 15m. This allows the hull 110 to end its forward movement and switch to reverse movement at a position relatively far from the person U who has fallen into the water, which is between 5m and 15m away.

[0086] In this embodiment, as described above, the waiting distance D1 is set to a predetermined distance of 1m to 3m. This prevents the hull 110 from moving closer to the person who has fallen overboard U than the predetermined waiting distance D1 of 1m to 3m during auto-return.

[0087] In this embodiment, as described above, the control unit 8 is configured to perform an automatic return of the hull 110 to the standby position P1 along a straight line path R connecting the remote control device 2 and the hull 110. This prevents the person who has fallen overboard U from feeling anxious as the hull 110 moves away from the person who has fallen overboard U during the automatic return.

[0088] In this embodiment, as described above, the system further includes a jet drive source 3 that drives the jet propulsion mechanism 4 to eject a jet of water, and a lanyard 7 which is held at one end by the operator and detachably connected to the hull 110 at the other end. The control unit 8 is configured to maintain the drive state of the jet drive source 3 and stop the movement of the hull 110 when the lanyard 7 is removed from the hull 110. This allows the drive state of the jet drive source 3 to be maintained even when the lanyard 7 is removed from the hull 110. In other words, it is possible to maintain a state in which turning control can be performed by the jet drive source 3. In addition, since the movement of the hull 110 can be stopped, it is possible to prevent the distance from the person who has fallen overboard U to the hull 110 from increasing.

[0089] In this embodiment, as described above, the stern 114 of the hull 110 is provided with a reboarding step 116 for a person U who has fallen overboard to place their feet on when boarding the vessel. When a person U falls overboard from the hull 110, the control unit 8 rotates the hull 110 to direct the stern 114, where the reboarding step 116 is located, toward the person U. This reduces the burden on the person U when re-boarding the hull 110 using the reboarding step 116.

[0090] (modified version) The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the description of the embodiments above, and further includes all modifications (modifications) within the meaning and scope equivalent to the claims.

[0091] For example, in the above embodiment, an example was shown in which the jet-propelled boat was configured as a so-called jet ski, but the present invention is not limited to this. In the present invention, the jet-propelled boat may be configured as a so-called jet-propelled sports boat.

[0092] In the above embodiment, the jet drive source for rotating the impeller was shown to include an engine, but the present invention is not limited to this. In the present invention, the jet drive source for rotating the impeller may include an electric motor.

[0093] In the above embodiment, an example was shown in which the control unit performs turning control and automatic return when the operator falls overboard, but the present invention is not limited to this. In the present invention, the control unit may also perform turning control and automatic return when a passenger sitting behind the operator falls overboard.

[0094] Furthermore, while the above embodiment shows an example of detecting a person falling into the water using a lanyard, the present invention is not limited to this. In the present invention, a person falling into the water may be detected using a remote control device such as a smartphone held by the person who has fallen into the water. For example, the location information of a remote control device such as a smartphone may be used to detect a person falling into the water when the remote control device moves away from the hull.

[0095] Furthermore, although the above embodiment shows an example in which the control unit performs auto-return, the present invention is not limited to this. In the present invention, if the control unit performs steering control, auto-return does not need to be performed.

[0096] Furthermore, although the above embodiment shows an example where the bow is pointed towards the person who has fallen overboard (remote control device) at the beginning of the auto-return, the present invention is not limited to this. In the present invention, the stern may always be pointed towards the person who has fallen overboard (remote control device) at the beginning of the auto-return (turning control may be performed). In other words, the vessel may move only in reverse without moving forward during the auto-return.

[0097] Furthermore, while the above embodiment shows an example where the reverse speed during auto-return is less than the forward speed, the present invention is not limited to this. In the present invention, the reverse speed during auto-return may be greater than or equal to the forward speed.

[0098] Furthermore, in the above embodiment, an example was shown in which the predetermined distance D2 (see Figure 11), which is the distance from the remote control device 2 (person who fell into the water U) to the intermediate position P2, was set to a predetermined distance of 5m or more and 15m or less. However, the present invention is not limited to this. In the present invention, the predetermined distance may be set to less than 5m or greater than 15m.

[0099] Furthermore, although the above embodiment shows an example in which the standby distance is set to a predetermined distance of 1m to 3m, the present invention is not limited to this. In the present invention, the standby distance may be set to less than 1m or greater than 3m. Note that the standby distance will be smaller than the predetermined distance which is the distance from the remote control device to the intermediate position.

[0100] Furthermore, in the above embodiment, for the sake of explanation, the processing operations of the control unit were described using a flow-driven flowchart that processes sequentially according to the processing flow, but the present invention is not limited thereto. In the present invention, the processing operations of the control unit may be performed by event-driven processing, which executes processing on an event-by-event basis. In this case, it may be performed as a completely event-driven system, or a combination of event-driven and flow-driven systems may be used. [Explanation of symbols]

[0101] 1 Communications Department 2. Remote control device (location information device) 3. Jet power source 4. Jet propulsion system 7 lanyards 8 Control Unit 44 nozzles 44a injection port 50 Steering Actuator 100 Jet-powered boats 110 hull 114 Stern 116 Reboarding Steps 120 Jet Propulsion System D0 Hull distance D1 Waiting distance D2 predetermined distance I1 Location information I2 Auto-return signal P1 Standby position P2 midway position R straight path U Fallen

Claims

1. A jet propulsion mechanism is provided, which includes a nozzle located at the stern of the hull and equipped with a jet of water nozzle, and generates thrust by ejecting a jet of water from the nozzle's nozzle opening. A steering actuator that rotates the nozzle in the left-right direction to change the direction of the jet of water flow from the nozzle in the left-right direction, A jet propulsion system comprising: a control unit that, in the event of a person falling overboard from the hull, injects a jet of water from the nozzle and rotates the hull using the steering actuator to control the stern of the vessel so that it faces the person who fell overboard.

2. A communication unit provided on the hull, The system further comprises a location information device, which is possessed by the person who fell into the water and transmits the location information of the person who fell into the water to the communication unit, The jet propulsion system according to claim 1, wherein the control unit, when a person falls overboard from the hull, performs turning control based on the position information to rotate the hull so that the stern faces the position information device.

3. The position information device is a remote control device that receives an auto-return instruction to automatically move the hull to a waiting position near the person who fell overboard. The jet propulsion system according to claim 2, wherein, when a person falls overboard from the hull, the control unit performs the auto-return to the standby position based on the auto-return signal and position information received from the remote control device, and performs the turning control to rotate the hull and point the stern toward the remote control device based on the position information.

4. The jet propulsion system according to claim 3, wherein the control unit, in the event of auto-return, performs the turning control and then controls the hull to move to the standby position in reverse while pointing the stern toward the remote control device.

5. The jet propulsion system according to claim 4, wherein the control unit, during the auto-return, moves the hull forward, performs the turning control to point the stern toward the remote control device at an intermediate position during the auto-return, and then controls the hull to move backward to the standby position.

6. The jet propulsion system according to claim 5, wherein the control unit is configured to move the hull in reverse at a speed less than the speed that moves the hull in forward motion during the auto-return operation.

7. The control unit, When the auto-return signal is received from the remote control device, if the distance from the remote control device to the hull is greater than a predetermined distance which is greater than the standby distance which is greater than the distance from the remote control device to the standby position, the hull is moved forward to the intermediate position which is the predetermined distance, and then the turning control is performed to point the stern toward the remote control device. The jet propulsion system according to claim 5, wherein when the auto-return signal is received from the remote control device, the system is configured to immediately perform the turning control if the distance to the hull is less than or equal to the predetermined distance.

8. The jet propulsion system according to claim 7, wherein the predetermined distance is set to a predetermined distance of 5 m or more and 15 m or less.

9. The jet propulsion system according to claim 7, wherein the standby distance is set to a predetermined distance of 1 m or more and 3 m or less.

10. The jet propulsion system according to claim 3, wherein the control unit is configured to perform the auto-return to the standby position of the hull along a straight line path connecting the remote control device and the hull.

11. A jet drive source that drives the jet propulsion mechanism and ejects a jet of water, The vessel further comprises a lanyard, one end of which is held by the helmsman and the other end of which is detachably connected to the hull, The jet propulsion system according to claim 1, wherein the control unit is configured to maintain the driving state of the jet drive source and stop the movement of the hull when the lanyard is removed from the hull.

12. The stern of the hull is provided with a reboarding step for the person who has fallen overboard to place their feet on when boarding the vessel. The jet propulsion system according to claim 1, wherein the control unit performs the turning control to rotate the hull so that the stern, on which the reboarding step is provided, faces the person who has fallen overboard when the person falls overboard from the hull.

13. The hull and, A jet propulsion mechanism is provided, which includes a nozzle located at the stern of the hull and equipped with a jet of water nozzle, and generates thrust by ejecting a jet of water from the nozzle's nozzle opening. A steering actuator that rotates the nozzle in the left-right direction to change the direction of the jet of water flow from the nozzle in the left-right direction, A jet-propelled boat comprising: a control unit that, in the event of a person falling overboard from the hull, injects a jet stream of water from the nozzle and rotates the hull using the steering actuator, thereby controlling the boat to turn its stern toward the person who fell overboard.

14. The vessel further comprises a communication unit that is installed on the hull, is held by the person who has fallen overboard, and communicates with a location information device that transmits location information of the person who has fallen overboard, The jet-powered boat according to claim 13, wherein the control unit, when a person falls overboard from the hull, performs turning control based on the position information to rotate the hull so that the stern faces the position information device.

15. The position information device is a remote control device that receives an auto-return instruction to automatically move the hull to a waiting position near the person who fell overboard. The jet-powered boat according to claim 14, wherein, when a person falls overboard from the hull, the control unit performs the auto-return to the standby position based on the auto-return signal and position information received from the remote control device, and performs the turning control to rotate the hull and point the stern toward the remote control device based on the position information.

16. The jet-powered boat according to claim 15, wherein the control unit, in the event of the auto-return, performs the turning control and then controls the hull to move in reverse to the standby position while pointing the stern toward the remote control device.

17. The jet-powered boat according to claim 16, wherein the control unit, during the auto-return, moves the hull forward, performs the turning control to point the stern toward the remote control device at an intermediate position during the auto-return, and then controls the hull to move backward to the standby position.

18. The jet-propelled boat according to claim 17, wherein the control unit is configured to make the speed at which the hull moves in reverse less than the speed at which the hull moves in forward during the auto-return operation.

19. The control unit, When the auto-return signal is received from the remote control device, if the distance from the remote control device to the hull is greater than a predetermined distance which is greater than the standby distance which is greater than the distance from the remote control device to the standby position, the hull is moved forward to the intermediate position which is the predetermined distance, and then the turning control is performed to point the stern toward the remote control device. The jet-powered boat according to claim 17, wherein, upon receiving the auto-return signal from the remote control device, the boat is configured to immediately perform the turning control if the distance to the hull is less than or equal to the predetermined distance.

20. The jet-propelled boat according to claim 19, wherein the predetermined distance is set to a predetermined distance of 5 m or more and 15 m or less.

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