JP2020090160A - Ship, ship navigation method - Google Patents

Abstract

To suppress deterioration of efficiency of propulsion by a propeller and efficiency of revolution by a thruster.SOLUTION: A ship 1 comprises a hull 2, a pair of propellers 4, a pair of rudders 5 and thrusters 6. The pair of propellers 4 are provided in a stern part 2b of the hull 2 at an interval in a ship lateral direction Dw. The pair of rudders 5 are provided for the pair of propellers 4 respectively on the stern side in a bow-stern direction Da. The thrusters 6 are provided between the pair of propellers 4 in the ship lateral direction Dw, and between the pair of propellers 4 and the pair of rudders 5 in the bow-stern direction Da. The thrusters 6 generate thrust force at least in the ship lateral direction Dw.SELECTED DRAWING: Figure 6

Description

The present invention relates to a ship and a navigation method for the ship.

The ship has a propeller and a rudder at the stern. In normal times, the propeller is rotated by the main engine provided inside the hull to obtain thrust in the bow-stern direction while adjusting the rudder direction for navigation. In addition, a ship may be equipped with a thruster used when berthing in a port. Thrusters generate thrust in the width direction of the ship to efficiently turn the ship and facilitate berthing.

For example, Patent Document 1 discloses a configuration in which a thruster is provided forward of the propeller and the rudder in the forward and rearward direction. Patent Document 1 also discloses a configuration in which a thruster is provided behind the propeller and the rudder in the rear direction of the bow. The thruster can be stored above the propeller boss that supports the shaft of the propeller. That is, the thruster has the same position in the ship width direction as the propeller in plan view.

Patent Document 2 discloses a ship that includes a propeller and a rudder provided at a central portion in the ship width direction as a main propulsion device, and a turning propeller on both sides in the ship width direction as a sub-propulsion device. The auxiliary thruster is provided so as to be rotatable along a horizontal plane. The auxiliary thruster is called an azimuth thruster or an azimuth thruster (hereinafter referred to as an azimuth thruster). The position of the azimuth thruster in the fore-and-aft direction in Patent Document 2 is equal to the position of the propeller of the main propulsion device in the fore-and-aft direction.

Japanese Utility Model Publication No. 61-82900 JP, 2008-27765, A

However, as disclosed in Patent Document 1, when the thruster is arranged forward or rearward of the propeller in the bow-stern direction, the water flow due to the thruster interferes with the water flow due to the propeller. Specifically, when a thruster is provided in the forward direction of the propeller with respect to the propeller, the water flow introduced into the propeller is disturbed by the water flow by the thruster when the thruster operates. This causes a decrease in propulsion efficiency due to the propeller. Further, as disclosed in Patent Document 1, when a thruster is provided behind the propeller in the bow-stern direction, the water flow by the propeller is disturbed by the water flow by the thruster in the ship width direction. This also reduces the propulsion efficiency of the propeller.
Further, the water flow from the thruster is also disturbed by the water flow from the propeller, which leads to a reduction in the turning efficiency of the ship using the thruster.

Even when the azimuth thrusters are arranged on both sides of the propeller in the ship width direction as in Patent Document 2, the same problem as in Patent Document 1 occurs. That is, when water flows are generated toward one side in the ship width direction by the azimuth thrusters on both sides of the propeller in the ship width direction, the water flow by the azimuth thrusters arranged on the other side in the ship width direction with respect to the propeller is Against from the side. This also disturbs the water flow from the propeller. Further, among the azimuth thrusters provided on both sides in the ship width direction with respect to the propeller, in the azimuth thruster on the side where the water flow hits the propeller, the water flow due to the azimuth thruster is disturbed. Therefore, the turning efficiency of the ship using the azimuth thruster is reduced.
The present invention has been made in view of the above circumstances, and suppresses that the water flow generated by the propeller and the water flow generated by the thruster interfere with each other to lower the propelling efficiency of the propeller and the turning efficiency of the thruster. It is an object of the present invention to provide a possible ship and a navigation method for the ship.

The present invention adopts the following means in order to solve the above problems.
According to the first aspect of the present invention, a ship includes a hull, a pair of propellers, a pair of rudders, and a thruster. The pair of propellers are provided on the stern of the hull at intervals in the ship width direction. The pair of rudders is provided on the stern side in the bow-stern direction of each of the pair of propellers. The thruster is provided between the pair of propellers in the ship width direction and between the pair of propellers and the pair of rudders in the bow-stern direction. The thruster generates a propulsive force at least in the ship width direction.

In a ship provided with a pair of propellers provided at intervals in the ship width direction, one propeller and the other propeller generate different thrust forces when turning in a port or the like. Specifically, when turning the ship so that the stern part of the hull moves from the first side in the width direction to the second side, the propeller on the second side in the width direction is set to the stern side in the stern direction. Generates a stream of water toward. On the other hand, with the propeller on the first side in the ship width direction, the water flow to the stern side in the stern direction is relatively weakened or the water flow to the bow side in the stern direction is relatively weaker than the propeller on the second side in the ship width direction. Or generate. As a result, a water flow from the second side to the first side in the ship width direction is generated between the pair of rudders in the bow-stern direction and the propeller between the pair of propellers in the ship width direction. As a result, the ship can be turned so that the stern of the ship moves from the first side in the ship width direction toward the second side.
The thruster is provided between the pair of propellers in the ship width direction and between the pair of propellers and the pair of rudders in the bow-stern direction. By generating a water flow from the second side to the first side in the ship width direction by this thruster, it is possible to prevent the water flow of the propeller from being disturbed by the water flow from the thruster. Further, the thruster generates a water flow from the second side to the first side in the ship width direction, so that the water flow from the second side to the first side generated by the pair of propellers can be strengthened.
Therefore, it is possible to prevent the water flow generated by the propeller and the water flow generated by the thruster from interfering with each other, thereby lowering the propulsion efficiency of the propeller and the turning efficiency of the thruster.

According to the second aspect of the present invention, the pair of propellers according to the first aspect may be capable of generating thrust in different directions in the bow-stern direction.
With this configuration, for example, at the time of turning in a harbor or the like, the thrust forces in the bow-stern direction of the one propeller and the other propeller can be different from each other. Specifically, when turning the ship so that the stern part of the hull moves from the first side in the width direction to the second side, the propeller on the second side in the width direction is set to the stern side in the stern direction. Generates a stream of water toward. On the other hand, the propeller on the first side in the ship width direction generates a water flow toward the bow side in the bow-stern direction. As a result, the water flow generated by the pair of propellers from the second side to the first side in the ship width direction can be strengthened. As a result, the ship can be efficiently turned.
Therefore, it is possible to further suppress the reduction of the propulsion efficiency due to the propeller and the turning efficiency due to the thruster.

According to the third aspect of the present invention, the ship according to the second aspect can switch between the first navigation mode and the second navigation mode. In the first navigation mode, a pair of the propellers generate a water flow toward the stern side in the stern direction, and propel the hull toward the bow side in the stern direction. The second navigation mode, of the pair of the propellers, the propeller on the first side in the ship width direction generates a water flow toward the bow side in the bow-stern direction, and the propeller on the second side in the ship width direction A water flow directed toward the stern side is generated, and a water flow directed from the second side in the ship width direction to the first side is generated by the thruster, and the stern part of the ship is swung from the first side in the ship width direction to the second side. ..
With this configuration, during the normal navigation, the navigation is performed in the first navigation mode, and when turning in a port or the like, the navigation is performed in the second navigation mode. In the second navigation mode, the propeller on the first side in the ship width direction generates a water flow toward the bow side in the bow-stern direction, and the propeller on the second side in the ship width direction generates a water flow toward the stern side in the bow-stern direction. As a result, the stern of the hull turns so as to move from the first side in the width direction to the second side. At this time, the turning efficiency of the hull is enhanced by generating a water flow from the second side to the first side in the ship width direction by the thruster.

According to the fourth aspect of the present invention, in the thruster according to any one of the first to third aspects, the direction of the water flow generated by the thruster can be switched in the ship width direction. Good.
With this configuration, for example, if the direction of the water flow generated by the thruster is switched in the ship width direction according to the turning direction of the ship, the turning efficiency of the ship can be increased in each turning direction. Further, since it is not necessary to rotate the thruster itself in the horizontal plane, the thruster can have a simple structure.

According to the fifth aspect of the present invention, the ship according to any one of the first to fourth aspects may be provided with a thruster housing portion that opens downward from the bottom surface of the stern portion. The thruster may be housed in the thruster housing so that the thruster can be retracted downward.
With this configuration, the thruster can be housed in the thruster housing when the thruster is not used. Therefore, during normal navigation, it is possible to prevent the additional resistance of the hull from increasing due to the thruster.

According to a sixth aspect of the present invention, in the marine vessel according to the fifth aspect, the bottom surface shape of the stern part of the hull is gradually inclined downward from both ends in the width direction toward the center part in the width direction, The thruster may be arranged at the center of the stern in the ship width direction.
With this configuration, it is easy to secure the height of the thruster housing portion in the center portion in the ship width direction. Further, when the thruster is projected downward when the thruster is used, the thrust dimension of the thruster from the bottom surface of the stern portion can be small. As a result, the moment acting on the thruster can be reduced, and the thruster structure can be prevented from becoming excessively large.

A seventh aspect of the present invention is the navigation method for a ship according to any one of the first to sixth aspects, wherein a pair of the propellers generate a water flow toward the stern side in the bow-stern direction, and the hull And a step of propelling to the bow side of the bow-stern direction, of the pair of the propellers, to generate a water flow toward the bow side of the bow-stern direction with the propeller on the ship width direction first side, The propeller generates a water flow toward the stern side in the stern direction, and the thruster generates a water flow from the second side in the width direction to the first side, and the stern portion of the ship is set to the first side in the width direction. To the second side.

With this configuration, when turning in a harbor, etc., the propeller on the first side of the ship width direction generates a water flow toward the bow side in the fore-and-aft direction, and the propeller on the second side of the ship width direction in the fore-and-aft direction. Generates a water flow to the side. As a result, the hull turns so that the stern part of the hull moves from the first side in the ship width direction to the second side. At this time, the turning efficiency of the hull is enhanced by generating a water flow from the second side to the first side in the ship width direction by the thruster.

According to the ship and the navigation method of the ship described above, it is possible to prevent the water flow generated by the propeller and the water flow generated by the thruster from interfering with each other, thereby lowering the propelling efficiency of the propeller and the turning efficiency of the thruster.

It is a side view which shows the structure of the stern part of the ship in one embodiment of this invention. It is the figure which looked at the stern part from the stern side in the stern direction. It is the figure which looked at the composition of the above-mentioned stern part from the upper part, and is an AA arrow sectional view of Drawing 2. It is a side view which shows the state which accommodated the thruster provided in the said stern part in the thruster accommodation part. It is a flowchart which shows the flow of the navigation method of the ship in the embodiment of this invention. It is a figure which shows the state which turns the stern part of the said hull from the starboard side to the port side in the ship width direction. It is a figure which shows the state which turns the stern part of the said hull from the port side in the ship width direction toward the starboard side. It is a top view which shows the structure of the stern part of the ship in the modification of one Embodiment of this invention.

Hereinafter, a ship and a navigation method of the ship according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a side view showing a configuration of a stern portion of a ship according to an embodiment of the present invention. FIG. 2 is a view of the stern section as viewed from the stern side in the stern direction. FIG. 3 is a view of the configuration of the stern portion as seen from above, and is a cross-sectional view taken along the line AA of FIG.
As shown in FIGS. 1 to 3, the boat 1 of this embodiment mainly includes a hull 2, a propeller drive mechanism 3, a pair of propellers 4, a pair of rudders 5, and a thruster 6.

The hull 2 includes a stern hull 21 that forms the stern portion 2b. The stern hull 21 has an inclined bottom surface (bottom surface) 23 on its bottom 22. The inclined bottom surface 23 is gradually inclined upward as it goes from the bow (not shown) side in the bow-stern direction Da toward the stern portion 2b side. When viewed from the stern side in the bow-stern direction Da, the rear portion 23a of the sloping bottom surface 23 is gradually inclined downward from both ends of the ship width direction Dw toward the center of the ship width direction Dw.

The propeller drive mechanism 3 is provided inside the hull 2. The propeller drive mechanism 3 includes a main engine 31 that independently rotationally drives each of the pair of propellers 4. The main engine 31 is composed of an internal combustion engine such as a diesel engine or an electric motor. The main engine 31 that drives one propeller 4 may be an internal combustion engine type, and the main engine 31 that drives the other propeller 4 may be an electric motor.

The pair of propellers 4 are provided on the stern portion 2b of the hull 2 at intervals in the ship width direction Dw. The pair of propellers 4 are provided on both sides of the center portion 2c of the hull 2 in the width direction of the boat.

Each propeller 4 is connected to the rear end of the propeller shaft 41. The propeller shaft 41 extends in the aft and rear direction Da. The front end of the propeller shaft 41 is connected to the main engine 31 arranged in the stern hull 21. The propeller shaft 41 is driven to rotate about its central axis by the main engine 31. The rear end of the propeller shaft 41 projects rearward in the stern-stern direction Da from inside the stern hull 21 via the bracket 25. The propeller 4 is integrally fixed to the rear end of the propeller shaft 41.

The propeller 4 is rotated in a predetermined direction when the propeller shaft 41 is rotationally driven around its central axis, and can generate a water flow toward the bow side and the stern side in the bow-stern direction Da. The thrust of propelling the hull 2 is exerted by this water flow. The propeller 4 illustrated in this embodiment is capable of forward and reverse rotations, respectively, and the direction of the water flow in the bow-stern direction Da (in other words, the generation direction) is switchable. As a result, the pair of propellers 4 can generate thrust in different directions in the bow-stern direction Da.

The pair of rudders 5 are provided on the stern portion 2b of the hull 2. The pair of rudders 5 are provided at intervals in the ship width direction Dw. One rudder 5 is provided for each of the pair of propellers 4 on the stern side in the bow-stern direction Da (see FIG. 3 ).

Each rudder 5 includes a support shaft 51 and a rudder main body 52. The support shaft 51 extends downward from a base portion 53 fixed to the inclined bottom surface 23 of the stern hull 21. The rudder main body 52 is plate-shaped and has a blade cross-sectional shape in a plan cross-sectional view. The rudder main body 52 is provided rotatably around the support shaft 51. The rudder 5 can change the direction of the rudder main body 52 by rotating the support shaft 51 by a rudder drive mechanism (not shown) provided in the stern hull 21. The pair of rudders 5 can independently change the direction of the rudder main body 52.

The thruster 6 is provided between the pair of propellers 4 and the pair of rudders 5 in the bow-aft direction Da. Further, the thruster 6 is provided between the pair of propellers 4 in the ship width direction Dw (see FIG. 2). The thruster 6 exemplified in this embodiment is arranged at the center in the ship width direction Dw.

The thruster 6 includes a base portion 61, a thruster screw 62, and a nozzle 63.
The base portion 61 is supported by a thruster lifting mechanism 64 (described later).
The thruster screw 62 is rotatably supported by the base portion 61. In this embodiment, the thruster screw 62 is rotatably provided around the central axis C extending in the ship width direction Dw. The thruster screw 62 is rotationally driven by a motor (not shown), the main machine 31, and the like.

The nozzle 63 is provided radially outside the thruster screw 62. The nozzle 63 has a tubular shape extending in the ship width direction Dw. When viewed from the stern side in the bow-stern direction Da, the nozzle 63 is formed so that the diameter dimension thereof gradually decreases from the port side L to the starboard side R in the ship width direction Dw.

The thruster 6 generates a propulsive force in the ship width direction Dw. The thruster 6 can switch the direction of the water flow generated by the thruster 6 between one side and the other side of the ship width direction Dw by switching the rotation direction of the thruster screw 62.

FIG. 4 is a side view showing a state where the thruster provided in the stern portion is accommodated in the thruster accommodating portion.
As shown in FIG. 4, the thruster 6 can be housed in a thruster housing portion 27 provided in the stern hull 21. The thruster accommodating portion 27 opens downward on the inclined bottom surface 23 of the stern hull 21. The thruster 6 is provided so as to be vertically movable by, for example, a cylinder mechanism as the thruster lifting mechanism 64. As a result, the thruster 6 is displaced between the projecting position (see FIG. 1) projecting downward from the thruster housing portion 27 and the housing position (see FIG. 4) housed inside the thruster housing portion 27. It is said that it is possible to appear and disappear. The thruster elevating mechanism 64 is not limited to the cylinder mechanism, and another mechanism may be appropriately used. In addition, a lid (not shown) that can close the opening may be provided at the opening of the thruster housing portion 27.

Here, the inclined bottom surface 23 of the stern hull 21 is gradually inclined downward from both ends of the ship width direction Dw toward the center of the ship width direction Dw (see FIG. 2 ). The thruster 6 is arranged at the center of the stern hull 21 in the ship width direction Dw. As a result, the height H (see FIG. 2) of the thruster housing portion 27 can be easily secured, and a larger thruster 6 can be housed.

Next, the navigation method of the ship 1 will be described.
FIG. 5 is a flow chart showing the flow of the navigation method for a ship according to the embodiment of the present invention. FIG. 6 is a diagram showing a state in which the stern part of the hull is turned from the starboard side to the port side in the ship width direction. FIG. 7: is a figure which shows the state which turns the stern part of the said hull toward the starboard side from the port side in the ship width direction.
As shown in FIG. 5, the navigation method of the boat 1 in the first embodiment includes a normal navigation step S1 and a harbor turning step S2.

In the normal navigation process S1, the ship 1 is caused to travel in the normal navigation mode (first navigation mode). In the normal navigation mode, as shown in FIG. 3, each of the pair of propellers 4 generates water flows Fp1 and Fp2 toward the stern side in the bow-stern direction Da. As a result, the hull 2 is propelled to the bow side in the bow-stern direction Da.

The harbor turning process S2 is executed, for example, when the ship 1 approaches and separates from the quay inside the harbor. In the harbor turning process S2, the ship 1 is made to sail in a turning mode (second sailing mode). The switching between the normal navigation mode and the turning mode may be performed by the operator manually switching the operations of the propeller 4 and the thruster 6, or may be automatically performed by the controller.

In the port turning step S2, when the stern portion 2b of the hull 2 is turned from the ship width direction Dw first side to the second side, as shown in FIGS. 6 and 7, of the pair of propellers 4, the ship width direction. The propeller 4 on the first side of Dw generates a water flow toward the bow side in the bow-stern direction Da. The propeller 4 on the second side in the ship width direction Dw generates a water flow toward the stern side in the bow-stern direction Da. That is, in the pair of propellers 4, one of the propellers 4 in the ship width direction Dw and the other propeller 4 have opposite water flow generation directions. In addition, the thruster 6 generates a water flow from the second side in the ship width direction Dw to the first side. Here, as will be described later in detail, the ship width direction Dw first side and the second side are switched according to the direction in which the stern portion 2b of the hull 2 is turned.

As shown in FIG. 6, when the stern portion 2b of the hull 2 is turned from the starboard side R in the ship width direction Dw to the port side L, the starboard side R is the ship width direction Dw first side, and the port side L is the ship. It becomes the width direction Dw second side. That is, of the pair of propellers 4, the propeller 4R on the starboard side R generates the water flow Fa1 toward the bow side in the bow-stern direction Da. Further, the propeller 4L on the port side L generates a water flow Fr1 toward the stern side in the bow-stern direction Da. Thereby, between the propeller 4 and the rudder 5 in the bow-stern direction Da, a water flow FWR is generated from the port side L (second side in the ship width direction Dw) to the starboard side R (first side in the ship width direction Dw). To be done. The thruster 6 generates a water flow Fw1 from the port side L in the ship width direction Dw to the starboard side R in the water flow FWR. Here, the rudder main bodies 52 of the pair of rudders 5 are respectively tilted so as to be arranged inside the ship width direction Dw as going from the bow side to the bow side to the bow side. As a result, a part of the water flow Fr1 of the propeller 4L is applied to the rudder main body 52 that is inclined so as to be arranged inside the ship width direction Dw as it goes from the bow side to the bow side to the stern side, and the hull 2 is turned. It can be a water flow in the direction of letting.
Therefore, as indicated by an arrow M1 in FIG. 6, the stern portion 2b of the hull 2 is turned from the starboard side R to the port side L in the ship width direction Dw.

On the other hand, as shown in FIG. 7, when the stern portion 2b of the hull 2 is turned from the port side L in the ship width direction Dw to the starboard side R, the port side L becomes the ship width direction Dw first side and the starboard side R becomes the ship width direction Dw second side. When the stern portion 2b of the hull 2 is turned from the port side L in the ship width direction Dw to the starboard side R, the water flow Fa2 toward the bow side in the stern direction Da with the propeller 4L on the port side L of the pair of propellers 4 To generate. Further, the propeller 4R on the starboard side R generates a water flow Fr2 toward the stern side in the bow-stern direction Da. Thereby, between the propeller 4 and the rudder 5 in the bow-stern direction Da, a water flow FWL is generated from the starboard side R (second side in the ship width direction Dw) to the port side L (first side in the ship width direction Dw). To be done. The thruster 6 generates a water flow Fw2 in the water flow FWL from the starboard side R to the port side L in the ship width direction Dw. At this time, the rudder main body 52 of the rudder 5 is tilted so as to be arranged inside the ship width direction Dw from the bow side to the bow side. As a result, a part of the water flow Fr2 of the propeller 4R hits the rudder main body 52 inclined so as to be arranged inside the ship width direction Dw as going from the bow side to the stern side of the bow direction Da, and the water flow in the ship width direction Dw. It becomes FWR.
Therefore, as shown by the arrow M2 in FIG. 7, the stern portion 2b of the hull 2 is turned from the port side L to the starboard side R in the ship width direction Dw.

In the above-described first embodiment, the ship 1 includes the pair of propellers 4 provided at intervals in the ship width direction Dw. This ship 1 makes thrust generated between one propeller 4 and the other propeller 4 different when turning in a harbor or the like. Specifically, when the boat 1 is turned so that the stern hull 21 of the hull 2 moves from the first side in the width direction to the second side, the propeller 4 on the second side in the width direction is used in the bow-stern direction. A water stream is generated toward the stern side of Da. On the other hand, the propeller 4 on the first side in the ship width direction generates a water flow to the bow side in the bow-stern direction Da. As a result, between the rudder 5 and the propeller 4 in the bow-stern direction Da, a water flow is generated between the pair of propellers 4 in the ship width direction Dw from the second side to the first side in the ship width direction Dw. As a result, the ship 1 can be turned so that the stern hull 21 moves from the first side in the ship width direction Dw toward the second side.
The thruster 6 is provided between the pair of propellers 4 in the ship width direction Dw and between the pair of propellers 4 and the pair of rudders 5 in the bow-stern direction Da. When the thrusters 6 generate the water flows Fw1 and Fw2 from the second side to the first side in the ship width direction Dw, the water flows Fa1 and Fa2 of the propeller 4 are prevented from being disturbed by the water flows Fw1 and Fw2 from the thruster 6. it can. Further, the thruster 6 generates the water flows Fw1 and Fw2 flowing from the second side to the first side in the ship width direction Dw, so that the water flows FWR and FWL generated by the pair of propellers 4 from the second side to the first side are generated. Can be strengthened. Therefore, it is possible to prevent the propelling efficiency of the propeller 4 and the turning efficiency of the thruster 6 from decreasing.

The pair of propellers 4 can generate thrust in different directions in the bow-stern direction Da. With this configuration, when the boat 1 is turned so that the stern hull 21 of the hull 2 moves from the ship width direction Dw first side toward the second side, the propeller 4 on the ship width direction Dw second side. Then, the water flows Fr1 and Fr2 are generated toward the stern side in the bow-stern direction Da. On the other hand, in the propeller 4 on the first side in the ship width direction Dw, water flows Fa1 and Fa2 are generated toward the bow side in the bow-stern direction Da. As a result, the water flows FWR and FWL generated by the pair of propellers 4 from the second side to the first side in the ship width direction Dw can be strengthened.
Therefore, it is possible to further suppress the reduction of the propulsion efficiency by the propeller 4 and the turning efficiency by the thruster 6.

Further, the ship 1 navigates in the first navigation mode during normal navigation, and in the second navigation mode during turning in a harbor or the like. In the second navigation mode, the propellers 4 on the first side in the width direction Dw generate water flows Fa1 and Fa2 toward the bow side in the bow-stern direction Da, and the propellers 4 on the second side in the width direction Dw move in the bow-stern direction Da. The water flows Fr1 and Fr2 toward the stern side are generated. As a result, the hull 2 turns so that the stern part of the hull 2 moves from the first side in the ship width direction Dw to the second side. At this time, the thrusters 6 generate water flows Fw1 and Fw2 from the second side to the first side in the ship width direction Dw, whereby the turning efficiency of the hull 2 is enhanced.

The thruster 6 can switch the direction of the generated water flow between one side and the other side of the ship width direction Dw. With such a configuration, the direction of the water flow generated by the thruster 6 may be switched between one side and the other side of the ship width direction Dw according to the turning direction of the hull 2. Therefore, it is not necessary to rotate the thruster 6 itself in the horizontal plane, and the thruster 6 can have a simple structure.

Further, the thruster 6 is provided so as to be able to project and retract downward from a thruster housing portion 27 provided on the inclined bottom surface 23 of the stern hull 21. With this configuration, the thruster 6 can be housed in the thruster housing portion 27 when the thruster 6 is not used. As a result, it is possible to prevent the additional resistance of the hull 2 generated by the thruster 6 from increasing during normal navigation.

Further, the shape of the inclined bottom surface 23 of the stern hull 21 gradually inclines downward from both ends in the ship width direction Dw toward the ship width direction Dw center, and the thruster 6 is the ship width direction Dw center of the stern hull 21. It is located in the section. With such a configuration, it is possible to secure a large height H of the thruster housing portion 27 in the central portion of the ship width direction Dw. Further, when the thruster 6 is projected downward when the thruster 6 is used, the projecting dimension of the thruster 6 from the inclined bottom surface 23 of the stern hull 21 may be small. As a result, the moment acting on the thruster 6 can be reduced, and the structure of the thruster 6 can be prevented from becoming excessively large.

(Modification of the embodiment)
Here, in the above-described embodiment, the thruster 6 itself is prevented from turning in the horizontal plane, but the present invention is not limited to this.
FIG. 8: is a top view which shows the structure of the stern part of the ship in the modification of the embodiment of the said ship.
As shown in FIG. 8, the thruster 6B may be provided so as to be rotatable in a horizontal plane. In such a thruster 6B, at the time of turning, the thruster screw 62 directs the thruster screw 62 toward the port side L or the starboard side R in the ship width direction Dw and exerts thrust in the ship width direction Dw. Further, the thruster 6B may direct the thruster screw 62 toward the stern side in the bow-stern direction Da during normal navigation to assist the thrust of the pair of propellers 4 during normal navigation of the ship 1.

(Other modifications)
The present invention is not limited to the above-described embodiment, and includes various modifications of the above-described embodiment without departing from the spirit of the present invention. That is, the specific shapes and configurations mentioned in the embodiments are merely examples, and can be appropriately changed.
For example, in the above embodiment, when turning, the propeller 4 on the first side of the ship width direction Dw and the propeller 4 on the second side of the ship width direction Dw have different water flow generation directions in the bow-stern direction Da. However, it is not limited to this. The propellers 4 on the ship width direction Dw first side and the propellers 4 on the ship width direction Dw second side are made to have different rotational speeds, so that the strength of the water flow in the bow-stern direction Da is made different to thereby make the ship width direction Dw. A water flow from the first side to the second side may be generated. For example, when the ship 1 is turned so that the stern hull 21 of the hull 2 moves from the ship width direction Dw first side toward the second side, the bow-stern direction Da is applied to the propeller 4 on the ship width direction Dw second side. Generates a stream of water toward the stern side of. On the other hand, in the propeller 4 on the first side in the ship width direction Dw, the water flow generated toward the stern side in the bow-stern direction Da is weaker than that in the propeller 4 on the second side in the ship width direction Dw. At this time, the thruster 6 produces a water flow from the second side in the ship width direction Dw to the first side. Also by this, the ship 1 can be turned.

Further, the thruster 6 may not be housed in the thruster housing portion 27 and may be always exposed. The inclined bottom surface 23 of the stern hull 21 may be flat.

Further, in the above-described embodiment, the case where the central axis C of the thruster 6 is disposed above the rotation center of the propeller 4 in the ship height direction when the thruster 6 is used has been illustrated. However, the central axis C may be arranged at the same position as or below the center of rotation of the propeller 4. The farther the central axis C is from the draft when the thruster 6 is used, the more advantageous it is in being less affected by waves. On the other hand, when the thruster 6 is used, the thruster 6 may be arranged above the ship bottom 22. By doing so, when the water depth is shallow, it is possible to prevent the thruster 6 from coming into contact with the water bottom or entraining gravel or the like on the water bottom.

In the above embodiment, the thruster 6 has only one thruster screw 62. However, the thruster 6 may include a thruster screw 62 that generates a water flow toward the first side in the ship width direction and a thruster screw 62 that generates a water flow toward the second side in the ship width direction. In this case, each thruster screw 62 can generate a water flow toward the first side and a water flow toward the second side in the ship width direction.

Further, in the above-described embodiment, the case where the pair of propeller shafts 41 can be rotated forward and backward is illustrated. However, as long as a pair of propellers can be used to generate a water flow toward the bow side in the bow-stern direction and a water flow toward the bow side, the water flow is not limited to the forward and reverse directions. For example, using a propeller with a variable blade angle (in other words, a variable pitch propeller), one propeller of a pair of propellers is set to a blade angle that generates a water flow toward the bow side in the bow-stern direction, and the other propeller is used. May be set to a blade angle that generates a water flow toward the stern side in the stern direction.

1 Vessel 2 Hull 2b Stern 2c Stern Width Center 3 Propeller Drive Mechanism 4, 4L, 4R Propeller 5 Rudder 6, 6B Thruster 21 Stern Hull 22 Ship Bottom 23 Sloping Bottom (Bottom)
23a: Rear part 25 Bracket 27 Thruster accommodating part 31 Main engine 41 Propeller shaft 51 Support shaft 52 Rudder main body 53 Base part 61 Base part 62 Thruster screw 63 Nozzle 64 Thruster lifting mechanism Da Bow direction Dw Ship width direction Fa1, Fa2: Water flow Fp1, Fp2: Water flow Fr1, Fr2: Water flow Fw1, Fw2: Water flow H Height L: Port side R: Starboard side M1, M2 Arrow S1 Normal navigation process S2 Port turning process

Claims (7)

The hull,
A pair of propellers provided at intervals in the ship width direction on the stern of the hull,
For each of the pair of propellers, a pair of rudders provided on the stern side in the bow-stern direction,
A ship provided between the pair of propellers in the ship width direction, and between the pair of propellers in the bow-stern direction and the pair of rudders, and a thruster that generates a propulsive force at least in the ship width direction. The marine vessel according to claim 1, wherein the pair of propellers can generate thrust in mutually different directions in the bow-stern direction. A first navigation mode in which a pair of the propellers generate a water flow toward the stern side in the stern direction, and propel the hull toward the stern side in the stern direction,
Among the pair of the propellers, a water flow directed toward the bow side in the bow-stern direction is generated by the propeller on the ship width direction first side, and a water flow directed toward the stern side in the bow-stern direction by the propeller on the ship width direction second side is generated. A second navigation mode in which the thruster generates a water flow from the ship width direction second side to the first side, and the stern of the ship turns from the ship width direction first side to the second side. The ship according to claim 2, wherein the ship is switchable. The said thruster is a ship as described in any one of Claim 1 to 3 which can switch the direction of the water flow produced by the said thruster in the ship width direction. A thruster housing that opens downward from the bottom of the stern,
The marine vessel according to any one of claims 1 to 4, wherein the thruster is accommodated in the thruster accommodating portion so as to be capable of appearing and retracting downward. The bottom shape of the stern of the hull is gradually inclined downward from both ends in the ship width direction toward the center in the ship width direction,
The marine vessel according to claim 5, wherein the thruster is arranged at a central portion of the stern portion in the ship width direction. A navigation method for a ship according to any one of claims 1 to 6, wherein:
Generating a water flow toward the stern side in the stern direction with a pair of the propellers, and propelling the hull toward the bow side in the stern direction,
Among the pair of the propellers, a water flow directed toward the bow side in the bow-stern direction is generated by the propeller on the ship width direction first side, and a water flow directed toward the stern side in the bow-stern direction by the propeller on the ship width direction second side is generated. A step of generating a water flow from the ship width direction second side to the first side with the thruster, and turning the stern of the ship from the ship width direction first side to the second side,
Ship navigation methods including.

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