Two-propeller four-rudder ship

Abstract

To provide a two propeller four-rudder ship with an excellent maneuvering performance capable of easily performing a direction control and a speed control.SOLUTION: A twin-propeller four-rudder ship comprises a pair of propeller shafts rotating in the mutually opposite direction, a pair of left and right propulsion propellers 101a, b equipped on each propeller shaft, arranged at the stern and having mutually opposite wing angle, a pair of left and right high-lift rudders 102a, b, 103a, b arranged behind each of the propulsion propellers 101a, b, and multiple steering gears 104a, b, 105a, b to drive each of the high-lift rudders 102a, b, 103a, b. The ship independently causes to operate each of the high-lift rudders 102a, b, 103a, b by each of the steering gears 104a, b, 105a, b in the state where the left and right propulsion propellers 101a, b rotate at a constant rate in the forward direction. The ship controls the propeller wake flow direction of each of the propulsion propellers 101a, b and controls the thrust direction around the stern acting on the hull by changing the rudder angle combination of the pair of the high-lift rudders 104a, b or 105a, b corresponding to each of propulsion propellers 101a, b.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a twin-shaft, four-rudder ship with a pair of high-lift rudders behind each propeller, and relates to technology that enables easy maneuvering. [Background technology]

[0002] Conventionally, a twin-shaft, twin-rudder ship, as shown in Patent Document 1, for example, has a pair of left and right propellers arranged side by side at the rear of the hull, and a pair of left and right rudders arranged side by side at the rear of the hull behind the pair of left and right propellers and toward the center of the hull, and the pair of rudders have first guide surfaces on the inboard side that face each other and second guide surfaces on the outboard side that do not face each other, and the bulge of the second guide surface toward the outboard side protrudes beyond the bulge of the first guide surface toward the inboard side.

[0003] In addition, the twin-screw ship shown in Patent Document 2 has a pair of left and right skeg sections spaced apart in the width direction of the hull at the stern of the hull, a pair of left and right propellers arranged at the rear ends of the skeg sections, and a pair of left and right rudders arranged behind the propellers at the stern, and the rudders extend along the width direction of the hull and are equipped with movable fins that can rotate around an axis. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication 2010-195302 [Patent Document 2] Patent Publication No. 2012-35786 Summary of the Invention [Problem to be solved by the invention]

[0005] Traditionally, twin-shaft, twin-rudder ships have been adopted in many cases for medium- to high-speed vessels such as ferries, passenger ships, naval vessels, and patrol boats, as well as shallow draft or wide cargo ships. The propellers of the two shafts rotate in opposite directions on the inboard or outboard side, and the propeller wakes also form swirling flows in opposite directions, so the fluid forces involved in steering a twin-shaft, twin-rudder ship are complex, and it is not easy to estimate the ship motion.

[0006] In turning maneuvering, rotating one propeller in the forward direction and the other in the reverse direction makes it easy to turn, but because reversing the direction of the main engine and steering are complicated, there is a demand for improved maneuvering performance in terms of directional control and speed control.In addition, when one main engine becomes inoperable and the ship is steered only by the other main engine, steering is complicated, so easy maneuverability is required for twin-shaft ships.

[0007] As with twin-screw vessels, some vessels use a pair of podded propellers at the stern. The podded propellers are said to have good maneuverability because they rotate 360 ​​degrees, but because there is no rudder behind the propellers, their course-keeping performance is not very good.

[0008] The present invention is devised to solve the above-mentioned problems, and aims to provide a twin-propeller, four-rudder ship with excellent maneuverability that allows easy directional control and speed control. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, the twin-shaft, four-rudder ship of the present invention is equipped with a thrust system and a steering system that controls the thrust system, and the thrust system is equipped with a pair of propeller shafts that rotate in opposite directions, a pair of left and right propulsion propellers having opposite blade angles mounted on each propeller shaft and positioned at the stern, a pair of left and right high-lift rudders positioned behind each propulsion propeller, and a plurality of steering gears that drive each high-lift rudders, and the steering system is characterized in that, while the left and right propulsion propellers are rotating at a constant speed in the forward direction, each steering gear operates each of the high-lift rudders independently to various angles, and by changing the combination of rudder angles of the pair of high-lift rudders corresponding to each propulsion propeller, the steering control device controls the direction of the propeller wake of each propulsion propeller and controls the direction of thrust acting around the stern acting on the hull.

[0010] In the twin-propeller, four-rudder ship of the present invention, the steering control device is characterized in that it has a low-speed on-the-spot turning function unit which, during low-speed steering, sets a pair of high-lift rudders corresponding to one of the propulsion propellers to a reverse rudder angle, and sets a pair of high-lift rudders corresponding to the other propulsion propeller to a forward rudder angle, while the left and right propulsion propellers are rotating constantly at a low speed in the forward direction, thereby performing on-the-spot turning maneuvering.

[0011] In the twin-shaft, four-rudder ship of the present invention, the steering control device is characterized in that, during low-speed maneuvering, when the left and right propulsion propellers are rotating constantly at a low speed in the forward direction, it controls a pair of high-lift rudders corresponding to one of the propulsion propellers to increase or decrease the rudder angle within the astern steering angle range while maintaining them at symmetrical rudder angles, and controls a pair of high-lift rudders corresponding to the other propulsion propeller to increase or decrease the rudder angle within the forward steering angle range while maintaining them at symmetrical rudder angles, thereby controlling the moment around the stern acting on the hull and adjusting the turning speed during low-speed maneuvering. Effect of the Invention

[0012] With the above configuration, in the twin-screw, four-rudder ship of the present invention, by changing the combination of rudder angles of a pair of high-lift rudders corresponding to each propulsion propeller, each of the propeller wakes generated from each propulsion propeller can be reliably controlled independently by a pair of high-lift rudders, and the direction of thrust acting on the hull around the stern can be controlled, thereby achieving easy and stable maneuverability in the twin-screw ship.

[0013] Generally, rudder is not very effective at low speeds, so the power of the main engine is temporarily increased to strengthen the propeller wake, but this is not necessary with the twin-shaft, four-rudder ship of this invention.

[0014] In other words, in low-speed maneuvering with the twin-shaft, four-rudder ship of the present invention, with the left and right propulsion propellers rotating constantly at a low speed in the forward direction, by setting a pair of high-lift rudders corresponding to one of the propulsion propellers to a astern rudder angle, a astern thrust acts on one side of the stern, and by setting a pair of high-lift rudders corresponding to the other propulsion propeller to a forward rudder angle, a forward thrust acts on the other side of the stern, so that on-the-spot turning maneuvering can be achieved at low speeds without the need to reverse the main engine or increase power.

[0015] In addition, in the twin-shaft, four-rudder ship of the present invention, when maneuvering at low speeds, with the left and right propulsion propellers rotating at a constant slow speed in the forward direction, the rudder angle of a pair of high-lift rudders corresponding to one of the propulsion propellers can be controlled within the astern rudder angle range to adjust the magnitude of the astern thrust acting on one side of the stern, and the rudder angle of a pair of high-lift rudders corresponding to the other propulsion propeller can be controlled within the forward rudder angle range to adjust the forward thrust acting on the other side of the stern.This allows the turning speed to be adjusted during maneuvering at low speeds by controlling the moment around the stern acting on the hull without the need for reversing the main engine or increasing its power, thereby achieving maneuvering performance that allows easy control of the bow direction and turning speed. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram showing a thrust system and a steering system of a two-shaft, four-rudder ship according to an embodiment of the present invention. [Diagram 2]FIG. 2 is a schematic diagram showing an overview of a thrust system according to the embodiment; [Diagram 3] FIG. 2 is a side view showing the configuration of the stern and bow in the embodiment; [Figure 4] FIG. 2 is a schematic diagram showing a steering stand of the steering control device according to the embodiment; [Diagram 5] FIG. 2 is a block diagram showing a configuration of a ship steering stand according to the embodiment; [Figure 6] FIG. 4 is a schematic diagram showing the operating range of a high-lift rudder in the embodiment; [Figure 7] 5A and 5B are schematic diagrams showing the combined rudder angle and the propulsion direction of the high-lift rudder in (a) forward, (a) hover, and (c) reverse maneuvers in the embodiment; [Figure 8] FIG. 13 is a schematic diagram showing the combined rudder angle and propulsion direction of the high-lift rudder in each of the maneuvers of (d) forward left turn, (e) forward left turn, on-the-spot left turn (+ thruster thrust), (f) on-the-spot right turn (+ thruster thrust), and (g) astern left turn in the same embodiment. [Figure 9] FIG. 13 is a schematic diagram showing the combined rudder angle and propulsion direction of the high-lift rudder in each of the maneuvers of (h) forward right turn, (i) forward right turn, on-the-spot right turn (+ thruster thrust), (j) on-the-spot left turn (+ thruster thrust), and (k) astern right turn in the same embodiment. [Figure 10] 5 is a schematic diagram showing the combined rudder angle and the propulsion direction of the high-lift rudders in (n) spot turning starboard and (m) spot turning port maneuvers in low-speed maneuvers in the embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. (Configuration of the embodiment) The twin-propeller, four-rudder ship in this embodiment includes a thrust system 100 and a ship steering system (steering control device) 200 that controls the thrust system 100, as shown in FIGS.

[0018] The thrust system 100 comprises a pair of propeller shafts 110a, 110b rotating in opposite directions and arranged at the stern of the hull 110, a pair of left and right propulsion propellers 101a, 101b having opposite blade angles that are mounted on each propeller shaft 110a, 110b and arranged at the stern, and a pair of left and right high-lift rudders 102a, 102b on the starboard side and a pair of left and right high-lift rudders 103a, 103b on the port side arranged rearward of each propulsion propeller 101a, 101b.

[0019] Each of the high-lift rudders 102a, 102b, 103a, and 103b is configured to be able to steer 105° outboard (outboard side) and 35° inboard (inboard side). By independently operating the pair of high-lift rudders 102a, 102b on the starboard side or the pair of high-lift rudders 103a, 103b on the port side at various angles while rotating both propulsion propellers 101a, 101b in the forward direction, and changing the combination of the rudder angles of the pair of high-lift rudders 102a, 102b, 103a, and 103b on both sides, it is possible to distribute the propeller wake in a desired direction and freely change the thrust in each direction.

[0020] Therefore, by controlling the propeller wakes of the propellers 101a, 101b on both sides and controlling the thrust around the stern in all directions by 360°, the ship can be steered in forward and backward directions, stopped, turned forward, turned backward, etc., and the movement of the ship can be freely controlled.

[0021] Furthermore, the thrust system 100 includes rotary vane steering gears 104a, 104b, 105a, 105b that drive the high-lift rudders 102a, 102b, 103a, 103b, rudder control devices (servo amplifiers) 106a, 106b, 107a, 107b that control the rotary vane steering gears 104a, 104b, 105a, 105b, a bow thruster 108 arranged on the bow side of the hull 110 and a thruster control device 109 that controls the bow thruster 108, and main engines 111a, 111b that drive each propulsion propeller 101a, 101b.

[0022] In addition, pump units 151a, 151b, 152a, 152b, rudder angle transmitters 153a, 153b, 154a, 154b and feedback units 155a, 155b, 156a, 156b are connected to the rotary vane steering gears 104a, 104b, 105a, 105b, respectively, and the feedback units 155a, 155b, 156a, 156b are connected to the rudder control devices 106a, 106b, 107a, 107b.

[0023] The ship steering system 200, which constitutes a steering control device, is stored in a ship steering stand 250, and the stand housing has the following integrated therein: a gyro direction display unit 252 that displays the gyro direction of a gyro compass 251, an auto ship steering unit 253 that steers the ship in a steering mode by autopilot using a GPS compass, a joystick ship steering unit 255 that steers the ship in a steering mode by a joystick lever 254, a manual ship steering unit 257 that steers the ship in a steering mode by a manual steering wheel 256, a non-follow-up ship steering unit 259 that steers the ship in a steering mode by non-follow-up steering levers 258a, 258b, 258c, 258d, and a mode switching unit 261 that switches between the ship steering units using a mode switching switch 260.

[0024] Furthermore, the navigation system is provided with a display device 262 having a touch panel on the screen, an image control unit 263 for controlling the image displayed on the display device 262, an emergency stop unit 265 for operating in a steering mode in which the ship is stopped urgently over all steering modes by operating an emergency stop button 264, a rudder angle instruction unit 280 for giving an instruction rudder angle to the rotary vane steering gears 104a, 104b, 105a, 105b via the rudder control devices 106a, 106b, 107c, 107d, an electronic chart display unit 282 for displaying an electronic navigation chart on the display device 262, a course line setting unit 283 for setting the planned route of the ship on the electronic navigation chart, a course correction unit 284 for eliminating the positional deviation of the ship relative to the course line, a low speed range steering switch button 285 for switching to steering in the low speed range, and a low speed range steering unit 286 for steering in the low speed range.

[0025] The image control unit 263 selectively displays or simultaneously displays a chart display image 266 showing an electronic navigational chart, a gyro orientation display image 267 showing the gyro orientation, an orientation display unit operation image 268 for touch-operating the gyro orientation display unit 252 on the monitor screen, and an auto-pilot operation image 269 for touch-operating the auto-pilot unit 253 on the monitor screen.

[0026] The joystick operation unit 255 is configured so that the joystick lever 254 can be operated in either the X or Y direction, and the tilt direction of the joystick lever 254 controls the commanded direction of movement of the hull, and the tilt angle in the tilt direction controls the commanded speed in the bow-stern direction and the commanded speed in the hull turning direction.

[0027] The joystick steering unit 255 controls the rudder angles of the pair of high-lift rudders 102a, 102b, 103a, 103b on both sides to the rudder angles set according to the tilt direction of the joystick lever 254, and by combining the rudder angles of the high-lift rudders 102a, 102b, 103a, 103b on both sides, the thrust of the propeller wake is turned toward the desired direction, and the rotary vane steering gears 104a, 104b, 105a, 105b control the rudder angles of the pair of high-lift rudders 102a, 102b, 103a, 103b on both sides within the range of 105° to the outboard side and 35° to the inboard side (see FIG. 6). The basic combinations of rudder angles of the high-lift rudders 102a, 102b, 103a, and 103b, the states of the joystick lever 254, their names, propeller wake streamlines, and movement directions will be described with reference to Figs.

[0028] In Figures 7 to 9, the rudders are shown in horizontal cross section, and the rudder angles of each rudders are shown to the side or below. Rudder angles to the right are shown as positive (+) and to the left as negative (-), and names for combinations of these rudder angles are given. The propeller wake is shown with a thin arrow, and the resulting propulsion direction of the ship is shown with a thick hollow arrow.

[0029] The rudder angles shown below are examples in this embodiment and do not limit the invention. In the following, the pair of high-lift rudders 102a, 102b on both sides and the pair of high-lift rudders 103a, 103b have the same pattern, and the port rudders and starboard rudders described below are the port rudders and starboard rudders of the pair of high-lift rudders 102a, 102b, 103a, 103b on both sides, respectively.

[0030] 7, (a) "forward" is port rudder 0° and starboard rudder 0° for the pair of high-lift rudders 102a, 102b, 103a, 103b on both sides. Similarly, (b) "hover" (hull stopped in place) is port rudder -75° and starboard rudder +75°, and (c) "astern" is port rudder -105° and starboard rudder +105°.

[0031] As shown in Figure 8, (d) "forward left turn" is port rudder -35° and starboard rudder -35°, (e) "forward left turn" is port rudder -70° and starboard rudder -35°, (f) "astern left shift" is port rudder -105° and starboard rudder +45° to +75°, and (g) "astern left turn" is port rudder -105° and starboard rudder +75° to +105°.

[0032] As shown in Figure 9, (h) "forward starboard turn" is port rudder +35° and starboard rudder +35°, (i) "forward starboard turn" is port rudder +35° and starboard rudder +70°, (j) "reverse starboard pull" is port rudder -45° to -75° and starboard rudder +105°, and (k) "reverse starboard turn" is port rudder -75° to -105° and starboard rudder +105°.

[0033] In addition, (e) if thruster thrust of the bow thruster 108 is applied in the starboard direction during a "forward port turn," thereby increasing the port turning speed, this results in a "port-turn," and (i) if thruster thrust of the bow thruster 108 is applied in the port direction during a "forward port turn," thereby increasing the right turning speed, this results in a "port-turn."

[0034] Similarly, (f) if the thruster thrust of the bow thruster 108 is applied in the port direction during "astern shift to the left," thereby increasing the right turning speed, this results in a "right turn on the spot," and (j) if the thruster thrust of the bow thruster 108 is applied in the starboard direction during "astern shift to the right," thereby increasing the left turning speed, this results in a "left turn on the spot."

[0035] Furthermore, steering to move the hull in the forward direction while maintaining the bow heading is performed as follows: For example, (f) when "astern move to the left", thrust from the bow thruster 108 is applied in the starboard direction to move the hull to the left, and (j) when "astern move to the right", thrust from the bow thruster 108 is applied in the port direction to move the hull to the right.

[0036] In this way, a twin-shaft, four-rudder ship having a pair of high-lift rudders 102a, 102b and 103a, 103b on both sides and equipped with a bow thruster 108 can reliably control each of the propeller wakes generated from each propeller 101a, 101b independently with the pair of high-lift rudders 102a, 102b and 103a, 103b by variously changing the rudder angle combinations of the pair of high-lift rudders 102a, 102b and 103a, 103b on both sides corresponding to each propeller propeller 101a, 101bb, and thereby control the direction of thrust around the stern acting on the hull, thereby achieving easy and stable maneuverability in a twin-shaft ship.

[0037] When maneuvering in the low speed range, a low speed range maneuvering unit 286 for maneuvering in the low speed range is activated by pressing a low speed range maneuvering switch button 285. The low speed range maneuvering unit 286 has a low speed on the spot turning function unit 287 and a turning speed adjustment function unit 288, and activation of the low speed range maneuvering unit 286 switches the rudder angle control by the joystick lever 254 to the low speed range maneuvering mode.

[0038] The auto-steering unit 253 guides and controls the ship to a predetermined course based on the ship's current position information, guidance route information, and stationary holding position information obtained from a GPS compass and an electronic chart system.

[0039] When the emergency stop button 264 is pressed in an emergency, the emergency stopping unit 265 cancels the rudder angle related to the current maneuvering, regardless of the maneuvering state indicated by the joystick lever 254 or regardless of the maneuvering mode in which the ship is being maneuvered, and turns the port rudder 103 in the starboard direction (clockwise direction as seen from above) and the starboard rudder 102 in the starboard direction (counterclockwise direction as seen from above) until they are hard over (fully turned), thereby applying braking force to the ship to stop it.

[0040] The manual steering unit 257 steers the ship by controlling the rudder angles of the two high-lift rudders 102 and 103 through the rotation of a manual steering wheel 256 .

[0041] The non-follow-up steering unit 259 steers to starboard or port depending on the time that the non-follow-up steering levers 258a, 258b are operated to the left or right.

[0042] The operation of the above configuration will now be described.

[0043] Joystick control mode A joystick steering mode is selected by operating the mode switch 260. The joystick steering unit 255 uses a joystick lever 254 to command the direction of hull movement, bow / stern command thrust, and width command thrust.

[0044] In this maneuvering, a twin-shaft, four-rudder ship has a pair of high-lift rudders 102a, 102b and 103a, 103b on both sides and is equipped with a bow thruster 108. By changing the rudder angle combinations of the pair of high-lift rudders 102a, 102b and 103a, 103b on both sides corresponding to each propulsion propeller 101a, 101bb, the propeller wakes generated from each propulsion propeller 101a, 101b can be reliably controlled independently by the pair of high-lift rudders 102a, 102b and 103a, 103b, and the direction of thrust around the stern acting on the hull can be controlled in all directions of 360°, thereby achieving easy and stable maneuverability in a twin-shaft ship.

[0045] With this type of maneuvering, there is no need to reverse the thrust of the propeller (reverse the propeller), and all maneuvering control can be performed with the main engine always rotating in forward direction.By adjusting the rudder angle of both rudders, the ship's speed can be controlled finely and steplessly from the maximum forward speed corresponding to the propeller speed at that time, to the maximum reverse speed, without having to adjust the main engine speed.

[0046] Generally, rudder is not very effective at low speeds, so the output of the main engine is temporarily increased to strengthen the propeller wake, but this is not necessary with the twin-shaft, four-rudder ship according to this embodiment.

[0047] When performing low-speed maneuvering while traveling at low speed in a harbor or congested waters with the twin-propeller and four-rudder ship according to this embodiment, the low-speed range maneuvering unit 286 for maneuvering in the low-speed range is activated by pressing the low-speed range maneuvering switch button 285. Activating the low-speed range maneuvering unit 286 switches the rudder angle control by the joystick lever 254 to the low-speed range maneuvering mode.

[0048] In the low-speed maneuvering mode, the turning direction is indicated by tilting the joystick lever 254, and the low-speed on-the-spot turning function unit 287 adjusts the rudder angle of a pair of high-lift rudders 102a, 102b, 103a, 103b on both sides while the left and right propulsion propellers 101a, 101b rotate at a constant speed in the forward direction.

[0049] For example, in the maneuvering of (n) "turn right on the spot" shown in Fig. 10, a pair of high-lift rudders 103a, 103b on the starboard side corresponding to one of the propulsion propellers 101b on the starboard side are set to a reverse rudder angle, here -105°, +105°, so that a reverse thrust acts on the starboard side of the stern. Then, a pair of high-lift rudders 102a, 102b corresponding to the other propulsion propeller 101a on the port side are set to a forward rudder angle, here 0°, 0°, so that a forward thrust acts on the port side of the stern, so that a turn right on the spot maneuvering can be realized in the low speed range without the need for reverse operation or power increase operation of the main engines 111a, 111b. In this maneuvering, basically, the thruster thrust of the bow thruster 108 is not required, but the thruster thrust of the bow thruster 108 is used in some cases.

[0050] 10 (m) "turn left on the spot" maneuver is performed by setting the pair of high-lift rudders 103a, 103b on the starboard side corresponding to the starboard propeller 101b at a forward rudder angle, here 0°, 0°, so that forward thrust acts on the starboard side of the stern. Then, by setting the pair of high-lift rudders 102a, 102b corresponding to the other propeller propeller 101a on the port side at a reverse rudder angle, here -105°, +105°, so that reverse thrust acts on the port side of the stern, and therefore, the ship can be turned left on the spot maneuver at low speed without the need for reverse operation or power increase operation of the main engines 111a, 111b.

[0051] In the low-speed range maneuvering mode, while the left and right propulsion propellers 101a, 101b rotate constantly at a low speed in the forward direction, the turning speed adjustment function unit 288 controls the bow direction and turning speed according to the tilt angle of the joystick lever 254.

[0052] For example, during maneuvering for "turn right on the spot" (n) shown in Figure 10, the pair of starboard high-lift rudders 103a, 103b corresponding to one of the starboard propeller propellers 101b are controlled to maintain symmetrical rudder angles while increasing or decreasing them within the astern rudder angle range, here between -75° and -105° and +75° and +105°, according to the tilt angle of the joystick lever 254, thereby increasing or decreasing the astern thrust on the starboard side of the stern.

[0053] In addition, during maneuvering for "turn right on the spot" (n) shown in Figure 10, the pair of high-lift rudders 102a, 102b on the port side corresponding to the other port propulsion propeller 101a are controlled to be increased or decreased within the forward rudder angle range, here from -75° to 0° and +75° to 0°, while maintaining symmetrical rudder angles, according to the tilt angle of the joystick lever 254, thereby increasing or decreasing the forward thrust on the port side of the stern.

[0054] Here, the pair of high-lift rudders 102a, 102b on both sides and the pair of high-lift rudders 103a, 103b on both sides may be controlled simultaneously, or one of them may be controlled. The same applies to the "port turn" maneuver shown in Figure 10(b), and a description thereof will be omitted.

[0055] In this way, the turning speed during low-speed maneuvering is adjusted by controlling the moment around the stern acting on the hull without the need for reverse operation or power increase operation of the main engines 111a, 111b, thereby achieving maneuvering performance that enables easy control of the bow direction and turning speed.

[0056] Maneuvering mode with emergency stop section With a single action of pressing the emergency stop button 264, the emergency stop unit 265 is activated, and the ship can be stopped urgently, taking priority over all steering modes. That is, regardless of the steering mode of the joystick lever 254 or other steering modes, the emergency stop unit 265 switches to crash astern mode (the port rudder is steered 105° port and the starboard rudder is steered 105° starboard for the pair of high-lift rudders 102a, 102b, 103a, 103b on both sides, "ASTERN"), generating a very large braking force and astern force, so that the ship can be stopped in a much shorter time and distance than by steering the ship by reversing the propellers.

[0057] Also, even in the crash astern mode, there is no need to stop the main engines 111a, 111b and restart them in reverse, so there is no risk of an uncontrolled state during maneuvering, making it possible to quickly respond to emergencies during navigation.

[0058] Furthermore, if the ship needs to turn due to its characteristics or external disturbances while maneuvering using the emergency stopping unit 265, or if it is necessary to change the ship's forward direction, including its heading, by simply operating the joystick lever 254, the ship can be steered freely using the joystick lever 254 to take an avoiding maneuver, just like with a normal joystick operation.

[0059] Autopilot mode In normal ship navigation, the mode selector switch 260 is operated to select the autopilot mode.

[0060] An auto-piloting operation image 269 is displayed on the monitor screen of the display device 262, and the ship's position, the direction to proceed, the position to be reached, or the bow-stern line direction are input to the auto-pilot unit 253 by touching the monitor screen, and the ship is automatically guided and steered along the set course.

[0061] Furthermore, the electronic chart display unit 282 displays the electronic navigation chart as a chart display image 266 on the monitor screen of the display device 262, and the course line setting unit 283 sets the planned route of the ship on the electronic navigation chart.

[0062] The autopilot 253 appropriately controls the rudder angle based on the current position information of the ship, the guidance route information, and the anchorage holding position information. The autopilot holds the course indicated by the gyrocompass as the heading or bow-stern line heading set in the autopilot operation image 269.

[0063] Manual Pilot Mode A mode change switch 260 is operated to select a steering mode using the manual steering wheel 256. In this steering mode, the rudder angles of the pairs of high-lift rudders 102a, 102b, 103a, and 103b on both sides are instructed to the manual steering unit 257 by rotating the manual steering wheel 256, and the rudder angles of the two high-lift rudders 102a, 102b, 103a, and 103b are controlled to steer the ship.

[0064] Non-follow-up maneuvering mode A steering mode using the non-follow-up steering levers 258a, 258b is selected by operating the mode change switch 260. In this steering mode, the non-follow-up steering unit 259 steers each of the rotary vane steering gears 104a, 104b, 105a, 105b corresponding to the non-follow-up steering levers 258a, 258b to the starboard or port side depending on the time that the non-follow-up steering levers 258a, 258b are operated to the left or right. [Explanation of symbols]

[0065] 100 Thrust System 101 Propulsion Propeller 102a, 102b, 103a, 103b High-lift rudders 104a, 104b, 105a, 105b Rotary vane steering gear 106a, 106b, 107a, 107b Rudder control device 108 Bow Thruster 109 Thruster Control Device 110 Hull 110a, 110b Propeller shaft 151a, 151b, 152a, 152b pump units 153a, 153b, 154a, 154b Rudder angle transmitter 155a, 155b, 156a, 156b Feedback units 200 Steering System 250 Steering stand 251 Gyrocompass 252 Gyro direction display unit 253 Auto steering unit 254 Joystick Lever 255 Joystick Control Unit 256 Manual steering wheel 256 257 Manual steering unit 257 258a, 258b Non-follow-up steering lever 259 Non-follow-up steering section 260 Mode Switch 261 Mode switching section 262 Display Device 263 Image Control Unit 264 Emergency stop button 265 Emergency Stopping Department 266 Nautical Chart Display Images 267 Gyro Orientation Display Image 268 Direction display section operation image 269 ​​Auto-pilot operation image 280 Rudder angle indicator 282 Electronic Chart Display Unit 283 Course Line Setting Section 285 Low speed range steering switch button 286 Low Speed ​​Range Control Section 287 Low speed range on-the-spot turning function unit 288 Turning speed adjustment function section

Claims

1. The vessel is equipped with a thrust system and a steering system that controls the thrust system. The thrust system includes a pair of propeller shafts rotating in opposite directions, a pair of left and right propulsion propellers having opposite blade angles mounted on each propeller shaft and arranged at the stern, a pair of left and right high-lift rudders arranged behind each propulsion propeller, and a plurality of steering gears for driving each high-lift rudders, A twin-shaft, four-rudder ship characterized in that the steering system is equipped with a steering control device that operates each high-lift rudders independently to various angles using each steering gear while the left and right propulsion propellers are rotating at a constant rate in the forward direction, and changes the combination of rudder angles of the pair of high-lift rudders corresponding to each propulsion propeller, thereby controlling the direction of the propeller wake of each propulsion propeller and controlling the direction of thrust acting around the stern on the hull.

2. The twin-propeller, four-rudder ship as described in claim 1, characterized in that the steering control device has a low-speed on-the-spot turning function unit which, in low-speed maneuvering, sets a pair of high-lift rudders corresponding to one propulsion propeller to a reverse rudder angle, and sets a pair of high-lift rudders corresponding to the other propulsion propeller to a forward rudder angle, while the left and right propulsion propellers are rotating constantly at a low speed in the forward direction, thereby performing on-the-spot turning maneuvering.

3. The twin-shaft, four-rudder ship as described in claim 1, characterized in that the steering control device has a turning speed adjustment function unit that, in low-speed maneuvering, controls a pair of high-lift rudders corresponding to one of the propulsion propellers to increase or decrease the rudder angle within a astern steering angle range while maintaining the rudder angle of the pair of high-lift rudders corresponding to the other propulsion propeller at symmetrical rudder angles, while the left and right propulsion propellers are rotating at a constant low speed in the forward direction, and controls the rudder angle of the pair of high-lift rudders corresponding to the other propulsion propeller at symmetrical rudder angles while increasing or decreasing the rudder angle within a forward steering angle range, thereby controlling the moment around the stern acting on the hull and adjusting the turning speed during low-speed maneuvering.

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