Jet propulsion system, jet-propelled boat, and hull launching method

Abstract

The present invention provides a jet propulsion system, a jet-propelled boat, and a boat hull launching method that enable easy launching of the boat hull from a trailer. [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 nozzle 44a, a nozzle actuator 5a that rotates the nozzle 44 to change the direction of the jet water from the nozzle 44a, and a control unit 8 that performs oscillation control by repeatedly oscillating the nozzle 44 using the nozzle actuator 5a when lowering the hull 110 from the trailer T.

Description

Technical Field

[0001] This invention relates to a jet propulsion system, a jet propulsion boat, and a method for lowering a hull from a trailer.

Background Art

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

[0003] In Patent Document 1, a jet propulsion boat equipped with a jet propulsion mechanism is disclosed. When lowering the hull from a trailer, the jet propulsion boat is configured to generate a backward propulsion force by ejecting a jet water flow from the jet propulsion mechanism toward the front side, so as to lower it.

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 propulsion boat described in Patent Document 1, simply repeatedly applying a linear thrust in the lowering direction by ejecting a jet water flow from the jet propulsion mechanism toward the front side to the hull may not be able to move the hull in the lowering direction or may be difficult to move depending on the magnitude of the frictional resistance between the hull and the trailer. In this case, the hull lowering operation may require a great deal of labor and time. Therefore, it is required to facilitate the operation of lowering the hull from the trailer.

[0006] This invention was made to solve the above-mentioned problems, and one of its objectives is to provide a jet propulsion system, a jet propulsion boat, and a boat hull launching method that can easily perform the hull launching operation from a trailer. [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 with a jet of water nozzle; a nozzle actuator that rotates the nozzle to change the direction of the jet of water from the nozzle; and a control unit that performs oscillation control by repeatedly oscillating the nozzle using the nozzle actuator when the hull is lowered from the trailer.

[0008] In the jet propulsion system according to the first aspect of this invention, as described above, a control unit is provided that performs oscillation control by repeatedly oscillating the nozzle using a nozzle actuator when launching the hull from the trailer. This allows the hull to be oscillated and its position relative to the trailer to be shifted so as to relieve friction with the trailer at the same position when launching the hull. Therefore, even when it is difficult or impossible to move the hull in the launching direction by simply injecting a jet of water forward, the hull can be effectively moved in the launching direction by the oscillation of the nozzle. As a result, launching the hull from the trailer can be made easier.

[0009] In the jet propulsion system according to the first aspect described above, preferably, the nozzle actuator includes a steering actuator that rotates the nozzle in the left-right direction to change the direction of the jet water flow in the left-right direction, and the control unit performs oscillation control to swing the nozzle in the left-right direction using the steering actuator. With this configuration, the nozzle can be easily and repeatedly oscillated in the left-right direction by controlling the steering actuator. As a result, the hull launching operation from the trailer can be made easier.

[0010] In the jet propulsion system according to the first aspect described above, preferably, the system further comprises a remote control device for operating the hull remotely, and a communication unit provided on the hull for communicating with the remote control device, wherein the control unit performs oscillation control based on the receipt of an oscillation signal from the remote control device via the communication unit. With this configuration, oscillation control can be performed by operating the remote control device even when not on board the hull.

[0011] In this case, preferably, the remote control device includes a swing button that continuously transmits a swing signal during the pressing period in which the pressing operation continues, and the control unit performs swing control to swing the nozzle using a nozzle actuator based on the swing signal during the pressing period. With this configuration, the swing button can swing the nozzle and rock the ship's hull only while the operator of the swing button is intentionally operating the swing button.

[0012] In the configuration comprising the above-described remote control device and communication unit, preferably, the remote control device is configured to accept an operation to move the hull to a predetermined boarding position after the hull has been launched. With this configuration, following the rocking control that launches the hull by operating the remote control device, it is also possible to move the hull to a predetermined boarding position by operating the remote control device that instructed the rocking control.

[0013] In the jet propulsion system according to the first aspect described above, preferably, a reverse bucket is further provided to change the direction of the jet stream in the forward and backward directions, and the control unit is configured to generate a reverse thrust force using the reverse bucket while performing oscillation control. With this configuration, since a reverse thrust force can be generated by the reverse bucket at the same time as the nozzle is oscillating, the hull launching operation from the trailer can be made easier compared to when the nozzle is oscillating and the reverse thrust force is generated by the reverse bucket separately.

[0014] In the jet propulsion system according to the first aspect described above, preferably, a reverse bucket is further provided to change the direction of the jet stream in the longitudinal direction, the nozzle actuator includes a trim actuator that rotates the nozzle vertically to change the direction of the jet stream vertically, and the control unit is configured to direct the nozzle nozzle upward with the trim actuator and adjust the position of the reverse bucket relative to the nozzle while performing oscillation control, thereby enabling the jet stream to be injected in a direction that lifts the stern. With this configuration, the nozzle can be oscillated with the stern lifted by the jet stream whose direction has been adjusted by the trim actuator and the reverse bucket. In other words, the nozzle can be oscillated with reduced friction by reducing the contact area between the trailer and the hull. As a result, the hull can be launched from the trailer more easily.

[0015] In the configuration in which the control unit performs oscillation control using a steering actuator, it is preferable that the control unit is configured to oscillate the nozzle in the left-right direction within the maximum angular range in which the nozzle can be operated by the steering actuator. With this configuration, by oscillating the nozzle in the left-right direction within the maximum angular range, a large oscillation can be made to the hull, making the hull unloading operation from the trailer even easier.

[0016] In the configuration in which the control unit performs oscillation control using a steering actuator, it is preferable that the control unit is configured to oscillate the nozzle in the left-right direction with a period of 0.5 seconds to 4 seconds in the oscillation control. With this configuration, the hull can be effectively oscillated by the short-period left-right oscillation of the nozzle with a period of 0.5 seconds to 4 seconds.

[0017] In the configuration in which the control unit performs oscillation control using a steering actuator, preferably, the steering actuator includes an electric motor, a transmission gear that transmits the driving force of the electric motor to the nozzle, and a nozzle-side steering cable, one end of which is connected to the transmission gear and the other end to the nozzle, respectively, and which pushes and pulls the nozzle. The control unit controls the drive of the electric motor to push and pull the nozzle via the nozzle-side steering cable, thereby performing oscillation control to oscillate the nozzle in the left-right direction. With this configuration, the driving force of the electric motor can be transmitted to the nozzle via the transmission gear and the nozzle-side steering cable, making it easy to oscillate the nozzle in the left-right direction.

[0018] In this case, preferably, the steering actuator further includes a steering cable on the steering side, with one end and the other end connected to a transmission gear and a steering operating section, respectively, for pushing and pulling the steering operating section, and the control unit is configured to push and pull the steering operating section via the steering cable on the steering side in the oscillation control, thereby causing the steering operating section to oscillate as well. With this configuration, the hull can be oscillated not only by the nozzle but also by the steering operating section, thus allowing for a greater oscillation of the hull.

[0019] In the jet propulsion system according to the first aspect described above, preferably, the nozzle actuator includes a trim actuator that rotates the nozzle vertically to change the direction of the jet stream vertically, and the control unit is configured to oscillate the nozzle vertically using the trim actuator in the oscillation control. With this configuration, the nozzle can be easily and repeatedly oscillated vertically using the trim actuator. As a result, the hull can be launched from the trailer more easily.

[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 nozzle, which generates thrust by ejecting a jet of water from the nozzle nozzle, a nozzle actuator that rotates the nozzle to change the direction of the jet of water from the nozzle nozzle, and a control unit that performs oscillation control by repeatedly oscillating the nozzle using the nozzle actuator when the hull is lowered from the trailer.

[0021] In the jet-powered boat according to the second aspect of this invention, as described above, a control unit is provided that performs oscillation control by repeatedly oscillating the nozzle using a nozzle actuator when launching the hull from the trailer. This allows the hull to be oscillated and its position relative to the trailer to be shifted so as to relieve friction with the trailer at the same position when launching the hull. Therefore, even when it is difficult or impossible to move the hull in the launching direction by simply injecting a jet stream of water forward, the hull can be effectively moved in the launching direction by oscillating the nozzle. As a result, it is possible to provide a jet-powered boat that can be easily launched from the trailer.

[0022] In the jet propulsion boat according to the second aspect, preferably, the nozzle actuator includes a steering actuator that rotates the nozzle in the left - right direction to change the direction of the jet water flow, and the control unit performs rocking control to rock the nozzle in the left - right direction by the steering actuator. With such a configuration, by controlling the steering actuator, the nozzle can be easily rocked repeatedly in the left - right direction. As a result, the under - carriage operation of the hull from the trailer can be performed more easily.

[0023] In the jet propulsion boat according to the second aspect, preferably, it further includes a communication unit that communicates with a remote control device for remotely controlling the hull, and the control unit performs rocking control based on receiving a rocking signal from the remote control device via the communication unit. With such a configuration, by the remote control device, even if not on board the hull, the remote control device can be operated to perform rocking control.

[0024] In the configuration including the remote control device and the communication unit, preferably, the remote control device includes a rocking button that continues to transmit a rocking signal during a pressing - continuous period in which the pressing operation continues, and the control unit performs rocking control to rock the nozzle by the nozzle actuator based on the rocking signal during the pressing - continuous period. With such a configuration, by the rocking button, the nozzle can be rocked to sway the hull only while the operator of the rocking button operates the rocking button intentionally.

[0025] In the jet propulsion boat according to the second aspect, preferably, the remote control device is configured to receive an operation to move the hull to a predetermined boarding position after the under - carriage of the hull is completed. With such a configuration, following the rocking control to lower the hull by operating the remote control device, it is also possible to operate the remote control device that instructed the rocking control to move the hull to a predetermined boarding position.

[0026] In the jet-propelled boat according to the second aspect, preferably, it further includes a reverse bucket for changing the direction of the jet water flow in the front-rear direction, and the control unit is configured to be able to generate a reverse propulsion force by the reverse bucket while performing the swing control. With this configuration, it is possible to generate a reverse propulsion force by the reverse bucket simultaneously with swinging the nozzle. Therefore, compared with the case of individually performing swinging the nozzle and generating a reverse propulsion force by the reverse bucket, the hull lowering operation from the trailer can be performed more easily.

[0027] In the jet-propelled boat according to the second aspect, preferably, it further includes a reverse bucket for changing the direction of the jet water flow in the front-rear direction, the nozzle actuator includes a trim actuator for rotating the nozzle in the vertical direction to change the direction of the jet water flow in the vertical direction, and the control unit is configured to be able to inject the jet water flow in the direction of floating the stern by directing the injection port of the nozzle upward by the trim actuator and adjusting the position of the reverse bucket with respect to the nozzle while performing the swing control. With this configuration, the nozzle can be swung in a state where the stern is floated by the jet water flow whose direction is adjusted by the trim actuator and the reverse bucket. That is, the nozzle can be swung in a state where the contact area between the trailer and the hull is reduced and the friction is reduced. As a result, the hull lowering operation from the trailer can be performed more easily.

[0028] The hull lowering method in the third aspect of this invention includes a step of generating a reverse propulsion force by the jet water flow from the injection port of the nozzle of the jet propulsion mechanism when lowering the hull from the trailer, and a step of repeatedly swinging the nozzle when lowering the hull from the trailer.

[0029] In the third aspect of this invention, the hull launching method includes a step of repeatedly oscillating the nozzle when launching the hull from the trailer, as described above. This allows the hull to be oscillated and its position relative to the trailer to be shifted so as to relieve friction with the trailer at the same position when launching the hull. Therefore, even when it is difficult or impossible to move the hull in the launching direction by simply injecting a jet of water forward, the hull can be effectively moved in the launching direction by oscillating the nozzle. As a result, it is possible to provide a hull launching method that facilitates launching the hull from the trailer. [Effects of the Invention]

[0030] According to the present invention, as described above, it is possible to provide a jet propulsion system, a jet propulsion boat, and a boat hull launching method that enable easy launching of the boat hull from a trailer. [Brief explanation of the drawing]

[0031] [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 is a side view illustrating the arrangement of the trailer and jet-powered boat during launching operations. [Figure 5] This is a plan view showing the state in which oscillation control is being performed by the control unit of the jet propulsion system according to the embodiment. [Figure 6] 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 7] This figure shows the display screen of a remote control device for a jet propulsion system according to an embodiment. [Figure 8] 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 9] This is a schematic side view illustrating the vertical rotation (trim) of the nozzle of a jet propulsion mechanism according to an embodiment. [Figure 10] This is a schematic side view illustrating the vertical rotation of the reverse bucket of a jet propulsion mechanism according to an embodiment. [Figure 11] This is a side view illustrating the orientation of the nozzle and reverse bucket when the stern is lifted. [Figure 12] This is a magnified view of part A in Figure 2. [Figure 13] This diagram shows the operating section according to the embodiment, viewed from the rear. [Figure 14] This is a flowchart of the control process for oscillation control according to the embodiment. [Modes for carrying out the invention]

[0032] Hereinafter, one embodiment of the present invention will be described based on the drawings.

[0033] (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 14.

[0034] The jet-powered boat 100 shown in Figures 1 and 2 is a personal watercraft, configured to be operated by 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 left and right of the deck 112.

[0035] (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 GPS receiver 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 steering actuator 50 and the trim actuator 55 are nozzle actuators 5a that rotate the nozzle 44 to change the direction of the jet of water from the injection port 44a.

[0036] 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.

[0037] The jet propulsion system 120 (control unit 8) of this embodiment, as shown in Figures 4 and 5, is configured to perform oscillation control by repeatedly oscillating the nozzle 44 using the nozzle actuator 5a when the hull 110 is lowered from the trailer T. In principle, oscillation control is performed when there are no people on board the hull 110. Details of the oscillation control will be described later.

[0038] The trailer T, carrying the hull 110, is positioned on the land side towards the water surface by a vehicle V towing the trailer T. This position in contact with the water surface is an inclined surface K where the trailer T side is lower than the vehicle V side. At this time, the water intake port 40a at the bottom of the hull 110 is positioned underwater so that water can be drawn into the waterway 40 (see Figure 1). When the trailer T is launched, in a plan view it is formed in an inverted U shape with the stern 114 side (X2 direction side) open. The trailer T extends in the longitudinal direction of the hull 110 and has a pair of hull support sections T1 aligned in the left-right direction of the hull 110. The hull 110 is placed on the pair of hull support sections T1 from above. The hull 110 is positioned between the pair of hull support sections T1.

[0039] (Configuration of the communication unit and remote control device) The communication unit 1 shown in Figure 3 is installed on the hull 110. The communication unit 1 is configured to establish wireless communication with the remote control device 2. As an example, the communication unit 1 is configured to establish wireless communication with the remote control device 2 using Bluetooth®. Note that 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 6).

[0040] The remote control device 2 is held by the operator or assistant 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.

[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 the auto-return, fixed-point holding, and launching support. This launching support is the mode used when the above-mentioned rocking control is performed.

[0044] As shown in Figure 7, the remote control device 2 includes a swing button 23 used for controlling the swing of the lowering support. The swing button 23 is displayed at the bottom of the display screen 20 when the lowering support is selected. The swing button 23 is configured to continuously transmit a swing signal I1 to the control unit 8 to swing the nozzle 44 during the pressing period in which the pressing operation continues. The swing button 23 includes a left-right swing button 23a that repeatedly swings the nozzle 44 in the left-right direction, and an up-down swing button 23b that repeatedly swings the nozzle 44 in the up-down direction.

[0045] Furthermore, the remote control device 2 includes a stern float button 24 used during launching support. The stern float button 24 is a button that, during the continuous pressing period while the pressing operation is ongoing, sprays a jet of water in the direction that lifts the stern 114, i.e., almost directly downwards (see Figure 11). The stern float button 24 is configured to continuously transmit a stern float signal I2 (see Figure 3) to the control unit 8 during the continuous pressing period while the pressing operation is ongoing, instructing it to spray water in the direction that lifts the stern 114. As shown in Figure 11, the control unit 8 is configured to spray a jet of water in the direction that lifts the stern 114 (almost directly downwards) by using the trim actuator 55 (see Figure 9) to direct the nozzle 44a upwards while performing oscillation control, and by adjusting the position of the reverse bucket 45 relative to the nozzle 44. In other words, while the rocking button 23 is pressed, pressing the stern float button 24 will cause a jet of water to be ejected in the direction that lifts the stern 114. Even when the rocking button 23 is not pressed, pressing the stern float button 24 will cause a jet of water to be ejected in the direction that lifts the stern 114.

[0046] The remote control device 2 is configured to accept an operation to move the hull 110 to a predetermined boarding position after the hull 110 has been launched. Such an operation is performed, for example, by switching from launching support mode to remote control mode using the mode switching button 21, and then using the hull operation button 22 on the remote control device 2.

[0047] (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.

[0048] (Configuration of the jet propulsion system) 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.

[0049] 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.

[0050] The nozzle 43 shown in Figure 8 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.

[0051] The nozzle 44 shown in Figure 9 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.

[0052] The reverse bucket 45 shown in Figure 10 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.

[0053] (Configuration of the steering actuator) Referring to Figures 2 and 12, 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.

[0054] 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.

[0055] 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.

[0056] (Trim actuator configuration) The trim actuator 55 shown in Figure 9 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.

[0057] (Configuration of the reverse actuator) The reverse actuator 56 shown in Figure 10 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.

[0058] (Configuration of the control panel) As shown in Figure 13, the operating unit 6 includes a steering operating unit 60, a throttle lever 61, and a trim operating unit 62.

[0059] 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 12. As a result, the nozzle 44 rotates in the left and right directions.

[0060] The throttle lever 61 shown in Figure 13 is configured to increase or decrease the rotational speed of the impeller 42 (the opening 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 61.

[0061] 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.

[0062] 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.

[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, when lowering the hull 110 from the trailer T, the control unit 8 performs oscillation control by repeatedly oscillating the nozzle 44 using the nozzle actuator 5a. The control unit 8 performs oscillation control based on the receipt of the oscillation signal I1 from the remote control device 2 via the communication unit 1. The oscillation signal I1 is transmitted from the remote control device 2 during the pressing period in which the pressing operation continues.

[0065] In detail, the control unit 8 performs oscillation control to oscillate the nozzle 44 using the nozzle actuator 5a based on the oscillation signal I1 during the period in which the pressing operation on the oscillation button 23 of the remote control device 2 continues.

[0066] More specifically, during the continuous pressing period when the left-right swing button 23a is pressed, the control unit 8 performs swing control by using the steering actuator 50 to swing the nozzle 44 in the left-right direction. Also, during the continuous pressing period when the up-down swing button 23b is pressed, the control unit 8 is configured to swing the nozzle 44 in the up-down direction using the trim actuator 55 in the swing control.

[0067] Furthermore, the control unit 8 is configured to spray a jet of water in the direction of lifting the stern 114 (approximately directly downwards) by using the trim actuator 55 to direct the nozzle 44a upwards and adjusting the position of the reverse bucket 45 relative to the nozzle 44 while the rocking control is being performed (while the rocking button 23 is pressed) and during the period of continuous pressing of the stern float button 24.

[0068] Furthermore, in the oscillation control, the control unit 8 is configured to oscillate the nozzle 44 in the left-right direction within the maximum angular range in which the steering actuator 50 can operate the nozzle 44. In addition, the control unit 8 is configured to oscillate the nozzle 44 in the left-right direction with a period of 0.5 seconds to 4 seconds. Note that the oscillation period of the nozzle 44 is set to be shorter for smaller vessels.

[0069] Furthermore, the control unit 8 controls the drive of the electric motor 51 to push and pull the nozzle 44 via the nozzle-side steering cable 53, thereby performing oscillation control to swing the nozzle 44 in the left-right direction. In addition, the control unit 8 is configured to push and pull the steering control unit 60 via the steering cable 54 on the operating unit side, thereby causing the steering control unit 60 to swing as well.

[0070] During launching, the sequence of actions—generating thrust for backward movement using the jet water flow from the jet propulsion mechanism 4, swinging the nozzle 44 from side to side, swinging the nozzle 44 up and down, and floating the stern 114 using the jet water flow from the jet propulsion mechanism 4—is determined by the operator of the remote control device 2. Some of these actions may be performed simultaneously, or they may be performed individually.

[0071] Normally, during launching, the first step is to generate reverse thrust using the jet water flow from the jet propulsion system 4. If the launching of the hull 110 is not completed with reverse thrust alone, one example of subsequent actions is to swing the nozzle 44 from side to side while the reverse thrust is still being generated, or after the reverse thrust has been stopped. If the launching of the hull 110 is still not completed by swinging the nozzle 44 from side to side, then the nozzle 44 is swung up and down, or the stern 114 is made to float using the jet water flow from the jet propulsion system 4. Note that the up and down swinging of the nozzle 44 and the floating of the stern 114 using the jet water flow from the jet propulsion system 4 may be performed simultaneously with the swinging of the nozzle 44 from side to side, or after the swinging of the nozzle 44 from side to side has stopped.

[0072] (Flowchart of the control process for oscillation control) The control process flow for the oscillation control shown in Figure 14 will be explained below. Oscillation control is performed by the control unit 8. Oscillation control starts from the state where the lowering support mode is selected using the mode switching button 21 in the upper left corner of the screen of the remote control device 2.

[0073] In step S1, it is determined whether the + button for the engine speed of the hull control button 22 was pressed. If the + button was pressed, the process proceeds to step S2; otherwise, the process proceeds to step S3.

[0074] In step S2, a jet of water is ejected forward from the jet propulsion mechanism 4, generating a backward thrust of the magnitude set in step S1. The process then proceeds to step S3.

[0075] In step S3, it is determined whether or not the left-right swing button 23a of the remote control device 2 has been operated. If the left-right swing button 23a has been operated, the process proceeds to step S4; if it is determined that the left-right swing button 23a has not been operated, the process proceeds to step S5.

[0076] In step S4, the steering actuator 50 is driven to swing the nozzle 44 from side to side. The swinging of the nozzle 44 from side to side in step S4 continues only as long as the left / right swing button 23a is pressed. The process then proceeds to step S5.

[0077] In step S5, it is determined whether or not the up-and-down swing button 23b of the remote control device 2 has been operated. If the up-and-down swing button 23b has been operated, the process proceeds to step S6; otherwise, the process proceeds to step S7.

[0078] In step S6, the trim actuator 55 is driven to swing the nozzle 44 up and down. Then, the process proceeds to step S7. The up and down swinging of the nozzle 44 in step S6 continues only as long as the up and down swing button 23b is pressed.

[0079] In step S7, it is determined whether or not the stern float button 24 of the remote control device 2 has been operated. If the stern float button 24 has been operated, the process proceeds to step S8; otherwise, the process proceeds to step S9.

[0080] In step S8, the orientation of the trim actuator 55 and the reverse bucket 45 is adjusted so that a jet of water is injected in the direction (almost directly downwards) to lift the stern 114. Then, the process proceeds to step S9. The injection of the jet of water in the direction to lift the stern 114 in step S8 continues only as long as the stern lift button 24 is pressed.

[0081] In step S9, it is determined whether the mode switching button 21 has been operated to exit the lowering support (mode). If the lowering support has been exited, the process proceeds to the end. If the lowering support has not been exited, the process returns to step S1.

[0082] (Effects of the embodiment) In this embodiment, the following effects can be obtained.

[0083] In this embodiment, as described above, when launching the hull 110 from the trailer T, a control unit 8 is provided that performs oscillation control by repeatedly oscillating the nozzle 44 using the nozzle actuator 5a. This allows the hull 110 to be oscillated and its position relative to the trailer T to be shifted so as to relieve friction with the trailer T at the same position when launching the hull 110. Therefore, even if it is difficult or impossible to move the hull 110 in the launching direction by simply injecting a jet of water forward, the oscillating of the nozzle 44 can effectively move the hull 110 in the launching direction. As a result, launching the hull 110 from the trailer T can be made easier.

[0084] In this embodiment, as described above, the nozzle actuator 5a includes a steering actuator 50 that rotates the nozzle 44 in the left-right direction to change the direction of the jet water flow in the left-right direction, and the control unit 8 performs oscillation control to swing the nozzle 44 in the left-right direction using the steering actuator 50. As a result, by controlling the steering actuator 50, the nozzle 44 can be easily oscillated repeatedly in the left-right direction. Consequently, the ditching operation of the hull 110 from the trailer T can be made easier.

[0085] In this embodiment, as described above, the vessel further includes a remote control device 2 for operating the hull 110 remotely, and a communication unit 1 provided on the hull 110 for communicating with the remote control device 2. The control unit 8 performs oscillation control based on receiving an oscillation signal I1 from the remote control device 2 via the communication unit 1. This allows the remote control device 2 to be operated and oscillation control performed even when the operator is not on board the hull 110.

[0086] In this embodiment, as described above, the remote control device 2 includes a swing button 23 that continuously transmits a swing signal I1 during the pressing period in which the pressing operation continues, and the control unit 8 performs swing control to swing the nozzle 44 using the nozzle actuator 5a based on the swing signal I1 during the pressing period. As a result, the swing button 23 can swing the nozzle 44 and shake the hull 110 only while the operator of the swing button 23 is intentionally operating the swing button 23.

[0087] In this embodiment, as described above, the remote control device 2 is configured to accept an operation to move the hull 110 to a predetermined boarding position after the hull 110 has been launched. This allows the remote control device 2 to be operated to perform rocking control to launch the hull 110, and then the remote control device 2 that instructed the rocking control to be operated to move the hull 110 to a predetermined boarding position.

[0088] In this embodiment, as described above, a reverse bucket 45 is further provided to change the direction of the jet stream in the forward and backward directions, and the control unit 8 is configured to generate a reverse thrust force using the reverse bucket 45 while performing oscillation control. As a result, since the reverse thrust force can be generated by the reverse bucket 45 at the same time as the nozzle 44 is oscillated, the operation of launching the hull 110 from the trailer T can be made easier compared to the case where the oscillation of the nozzle 44 and the generation of a reverse thrust force using the reverse bucket 45 are performed separately.

[0089] In this embodiment, as described above, a reverse bucket 45 is further provided to change the direction of the jet stream in the front-rear direction, the nozzle actuator 5a includes a trim actuator 55 that rotates the nozzle 44 in the up-down direction to change the direction of the jet stream in the up-down direction, and the control unit 8 is configured to spray a jet stream in a direction that lifts the stern 114 by directing the nozzle 44a of the nozzle 44 upward with the trim actuator 55 and adjusting the position of the reverse bucket 45 relative to the nozzle 44 while performing oscillation control. As a result, the nozzle 44 can be oscillated with the stern 114 lifted by the jet stream whose direction has been adjusted by the trim actuator 55 and the reverse bucket 45. In other words, the nozzle 44 can be oscillated with reduced friction by reducing the contact area between the trailer T and the hull 110. As a result, the hull 110 can be lowered from the trailer T more easily.

[0090] In this embodiment, as described above, the control unit 8 is configured to swing the nozzle 44 in the left-right direction within the maximum angular range in which the steering actuator 50 can operate it during swing control. By swinging the nozzle 44 in the left-right direction within the maximum angular range, a large swing can be applied to the hull 110, making the ditching operation of the hull 110 from the trailer T even easier.

[0091] In this embodiment, as described above, the control unit 8 is configured to swing the nozzle 44 from side to side with a period of 0.5 seconds to 4 seconds in the oscillation control. This makes it possible to effectively oscillate the hull 110 by swinging the nozzle 44 from side to side with a short period of 0.5 seconds to 4 seconds.

[0092] In this embodiment, as described above, the steering actuator 50 includes an electric motor 51, a transmission gear 52 that transmits the driving force of the electric motor 51 to the nozzle 44, and a nozzle-side steering cable 53, one end of which is connected to the transmission gear 52 and the other end to the nozzle 44, respectively, and which pushes and pulls the nozzle 44. The control unit 8 controls the drive of the electric motor 51 to push and pull the nozzle 44 via the nozzle-side steering cable 53, thereby performing swing control to swing the nozzle 44 in the left-right direction. This allows the driving force of the electric motor 51 to be transmitted to the nozzle 44 via the transmission gear 52 and the nozzle-side steering cable 53, making it easy to swing the nozzle 44 in the left-right direction.

[0093] In this embodiment, as described above, the steering actuator 50 has one end connected to the transmission gear 52 and the steering operating unit 60, respectively, and further includes an operating unit-side steering cable 54 that pushes and pulls the steering operating unit 60. The control unit 8 is configured to push and pull the steering operating unit 60 via the operating unit-side steering cable 54 in the oscillation control, thereby causing the steering operating unit 60 to oscillate as well. As a result, the hull 110 can be oscillated not only by the nozzle 44 but also by the steering operating unit 60, thus allowing for a greater oscillation of the hull 110.

[0094] In this embodiment, as described above, the nozzle actuator 5a includes a trim actuator 55 that rotates the nozzle 44 vertically to change the direction of the jet water flow vertically, and the control unit 8 is configured to cause the nozzle 44 to swing vertically using the trim actuator 55 in the swing control. As a result, the nozzle 44 can be easily and repeatedly swung vertically using the trim actuator 55. Consequently, the ditching operation of the hull 110 from the trailer T can be made easier.

[0095] (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.

[0096] 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.

[0097] 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.

[0098] In the above embodiment, the order in which the following operations are performed during launching—"generation of reverse thrust by the jet water flow from the jet propulsion mechanism," "oscillation of the nozzle in the left-right direction," "oscillation of the nozzle in the up-down direction," and "floating of the stern by the jet water flow from the jet propulsion mechanism"—is determined by the operator of the remote control device. However, the present invention is not limited to this. In the present invention, the order in which the following operations are performed—"generation of reverse thrust by the jet water flow from the jet propulsion mechanism," "oscillation of the nozzle in the left-right direction," "oscillation of the nozzle in the up-down direction," and "floating of the stern by the jet water flow from the jet propulsion mechanism"—is predetermined, and the control unit may perform each operation in this order. In this case, the switching of each operation may be performed at predetermined time intervals, or the operator of the remote control device may perform it by operating a predetermined switching button.

[0099] In the above embodiment, an example was shown in which the remote control device includes a rocking button, but the present invention is not limited thereto. In the present invention, the hull may also include a rocking button. That is, the hull may be provided with a rocking button.

[0100] In the above embodiment, an example was shown in which the remote control device includes a stern float button, but the present invention is not limited thereto. In the present invention, the hull may include a stern float button. That is, the hull may be provided with a stern float button.

[0101] Furthermore, while the above embodiment shows an example in which the nozzle is oscillated left and right within the maximum angular range in which it can be operated during oscillation control, the present invention is not limited to this. In the present invention, the nozzle may be oscillated left and right within an angular range smaller than the above maximum angular range during oscillation control.

[0102] Furthermore, in the above embodiment, an example was shown in which the steering actuator is configured such that the steering control unit also swings when the nozzle is swung in the left-right direction by the steering actuator, but the present invention is not limited to this. In the present invention, the steering actuator may be configured so that the steering control unit does not swing when the nozzle is swung in the left-right direction by the steering actuator.

[0103] Furthermore, although the above embodiment shows an example in which the drive source of the steering actuator is an electric motor, the present invention is not limited to this. In the present invention, the drive source of the steering actuator may be a cylinder, a solenoid, or the like.

[0104] 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]

[0105] 1 Communications Department 2 Remote control device 4. Jet propulsion system 5a Nozzle Actuator 8 Control Unit 23. Swivel button 44 nozzles 44a injection port 45 Reverse Buckets 50 Steering Actuator 51 Electric motor 52 Transmission gear 53 Nozzle-side steering cable 54 Steering cable on the control panel side 55 Trim Actuator 60 Steering control unit 100 Jet-powered boats 110 hull 114 Stern 120 Jet Propulsion System I1 Oscillating signal T Trailer

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 nozzle actuator that rotates the nozzle to change the direction of the jet of water flow from the nozzle, A jet propulsion system comprising: a control unit that performs oscillation control by repeatedly oscillating the nozzle using the nozzle actuator when lowering the hull from the trailer.

2. The nozzle actuator includes a steering actuator that rotates the nozzle in the left-right direction to change the direction of the jet water flow in the left-right direction. The jet propulsion system according to claim 1, wherein the control unit performs the oscillation control to swing the nozzle in the left-right direction using the steering actuator.

3. A remote control device for operating the hull of the ship remotely, The ship further comprises a communication unit provided on the hull for communicating with the remote control device, The jet propulsion system according to claim 1, wherein the control unit performs the oscillation control based on the receipt of an oscillation signal from the remote control device via the communication unit.

4. The remote control device includes a swing button that continues to transmit the swing signal during the pressing period in which the pressing operation is continued. The jet propulsion system according to claim 3, wherein the control unit performs the oscillation control to oscillate the nozzle actuator based on the oscillation signal during the pressing duration period.

5. The jet propulsion system according to claim 3, wherein the remote control device is configured to accept an operation to move the hull to a predetermined boarding position after the hull has been launched.

6. It also features a reverse bucket that changes the direction of the jet stream in the forward and backward directions. The jet propulsion system according to claim 1, wherein the control unit is configured to generate a reverse thrust force with the reverse bucket while the oscillation control is being performed.

7. It also features a reverse bucket that changes the direction of the jet stream in the forward and backward directions. The nozzle actuator includes a trim actuator that rotates the nozzle vertically to change the direction of the water jet vertically. The jet propulsion system according to claim 1, wherein the control unit is configured to direct the nozzle's nozzle opening upward with the trim actuator and adjust the position of the reverse bucket relative to the nozzle while the oscillation control is being performed, thereby enabling the jet to be ejected in a direction that lifts the stern.

8. The jet propulsion system according to claim 2, wherein the control unit is configured to swing the nozzle in the left-right direction within the maximum angular range in which the steering actuator can operate the nozzle in the swing control.

9. The jet propulsion system according to claim 2, wherein the control unit is configured to oscillate the nozzle in the left-right direction with a period of 0.5 seconds or more and 4 seconds or less in the oscillation control.

10. The steering actuator is Electric motor and, A transmission gear that transmits the driving force of the electric motor to the nozzle, It includes a nozzle-side steering cable, one end of which is connected to the transmission gear and the nozzle, respectively, for pushing and pulling the nozzle, The jet propulsion system according to claim 2, wherein the control unit controls the drive of the electric motor to push and pull the nozzle via the nozzle-side steering cable, thereby performing the oscillation control to swing the nozzle in the left-right direction.

11. The steering actuator further includes an operating-side steering cable, one end of which is connected to the transmission gear and the steering operating section, and the other end of which is connected to the steering operating section, and which pushes and pulls the steering operating section. The jet propulsion system according to claim 10, wherein the control unit is configured to push and pull the steering control unit via the steering cable on the operating unit side, thereby causing the steering control unit to also oscillate.

12. The nozzle actuator includes a trim actuator that rotates the nozzle vertically to change the direction of the water jet vertically. The jet propulsion system according to claim 1, wherein the control unit is configured to cause the nozzle to swing up and down using the trim actuator in the oscillation control.

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 nozzle actuator that rotates the nozzle to change the direction of the jet of water flow from the nozzle, A jet-propelled boat comprising a control unit that performs oscillation control by repeatedly oscillating the nozzle using the nozzle actuator when the hull is lowered from the trailer.

14. The nozzle actuator includes a steering actuator that rotates the nozzle in the left-right direction to change the direction of the jet water flow in the left-right direction. The jet propulsion boat according to claim 13, wherein the control unit performs the oscillation control to swing the nozzle in the left-right direction using the steering actuator.

15. The vessel is further equipped with a communication unit that communicates with a remote control device that operates the vessel remotely, The jet propulsion boat according to claim 13, wherein the control unit performs the oscillation control based on the receipt of an oscillation signal from the remote control device via the communication unit.

16. The remote control device includes a swing button that continues to transmit the swing signal during the pressing period in which the pressing operation is continued. The jet propulsion boat according to claim 15, wherein the control unit performs the oscillation control to oscillate the nozzle actuator based on the oscillation signal during the pressing duration period.

17. The jet-powered boat according to claim 15, wherein the remote control device is configured to accept an operation to move the hull to a predetermined boarding position after the hull has been launched.

18. It also features a reverse bucket that changes the direction of the jet stream in the forward and backward directions. The jet-propelled boat according to claim 13, wherein the control unit is configured to generate a reverse thrust force with the reverse bucket while the oscillation control is being performed.

19. It also features a reverse bucket that changes the direction of the jet stream in the forward and backward directions. The nozzle actuator includes a trim actuator that rotates the nozzle vertically to change the direction of the water jet vertically. The jet-propelled boat according to claim 13, wherein the control unit is configured to direct the nozzle's nozzle opening upward with the trim actuator and adjust the position of the reverse bucket relative to the nozzle while the oscillation control is being performed, thereby enabling the jet stream to be ejected in a direction that lifts the stern.

20. When lowering the hull from the trailer, the jet propulsion mechanism generates backward thrust using a jet of water from its nozzle. A method for launching a ship, comprising the step of repeatedly oscillating the nozzle when launching the ship from the trailer.

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