JP6160804B2 - Two-rudder system and ship equipped with two-rudder system - Google Patents

Description

  The present invention relates to a two-rudder system and a two-rudder equipped with a propeller attached to the rear end of a stern tube of a hull, two rudder plates, and driving means for driving the two rudder plates via a drive shaft. It relates to ships equipped with the system.

The rudder is generally arranged behind the propeller for the purpose of increasing the steering force and using the acceleration flow of the propeller.
However, in a wide enlarged ship, the stern flow becomes unstable, and the course stability is extremely deteriorated. In order to further improve maneuverability, the rudder has been enlarged, but the propeller and rudder storage space at the stern has become insufficient, and the propeller has come extremely close to the hull, deteriorating propulsion performance.
From the ship's history, the means of propelling the ship has been replaced by the propeller era in which the main engine drives the propeller from the past sailing ship sailing era, but the shape and position of the rudder has not changed from the sailing ship era. . In today's era when global warming prevention measures are required, it is necessary to pursue the use of rudder as an energy-saving device in addition to the original rudder.

Patent document 1 and patent document 2 are the ships which have arrange | positioned the rudder behind the propeller.
In patent document 3, the structure which arrange | positions two rudder plates to the side of a propeller is proposed (FIG. 8 and paragraph number (0019)).
In Patent Document 4, the rudder is located in front of the propeller.

JP 2012-131475 A JP 50-55094 A JP 2010-13087 A JP 2003-11893 A

In Patent Document 1 and Patent Document 2, the rudder thrust is not generated because the rudder is disposed behind the propeller.
Patent Document 3 arranges two rudder plates on the side of the propeller, but the two rudder plates form a curved surface on the outside and do not form a camber with the inside as a flat surface, Rectification of the wake of the propeller that flows between the two rudder blades is planned.
That is, in Patent Document 3, the outer flow becomes faster due to the outer curve of the rudder plate, and a flow from the inner side to the outer side is generated at the front edge of the rudder plate. As a result, the inner flow is decelerated. Therefore, lift is generated in the direction outside the rudder plate, but the direction is directed to the stern direction, which is a drag force, not the bow direction because the flow entering the rudder plate is toward the center of the hull. Therefore, in Patent Document 3, the propeller thrust is improved, but the rudder thrust is not generated.
Note that Patent Document 4 relates to an azimuth propulsion device, which is merely that the rudder is in front of the propeller, and the basic configuration of the rudder system is different in the first place.

  An object of the present invention is to provide a twin rudder system that generates rudder thrust by a rudder plate and enhances propulsion performance, and a ship equipped with the dual rudder system.

In the two-rudder system corresponding to the present invention described in claim 1, two rudder plates arranged on the side of the propeller attached to the rear end of the stern tube of the hull, and the two rudder plates are used as drive shafts. A two-rudder system having driving means for driving through two cambers formed inside the two rudder plates, and the two rudder plates can be driven independently by the driving means. The rudder plate is arranged so that the front portion of the rudder plate is located behind the upper end of the rudder plate and the front end of the propeller and is ahead of the propeller when not turning, and the drive shaft is The position in the front-rear direction is arranged at approximately the same position as the propeller, and the front part of one rudder plate is operated in the same rudder angle in the same direction by the driving means so as to approach the stern part at the time of turning, and each other by the driving means at the time of braking It is characterized by operating in the opposite direction. According to the first aspect of the present invention, the rudder plate can generate a stern flow rectification effect and reduce the flow to generate rudder thrust. Moreover, the braking distance of a ship can be shortened because two rudder plates operate | move to a mutually opposing direction.

  The present invention according to claim 2 is the dual rudder system according to claim 1, wherein the two rudder plates are provided with a camber effect due to contraction of the stern portion of the hull or an angle of attack effect on the stern flow. It is characterized by generating a thrust for propelling the hull forward. According to the second aspect of the present invention, the hull is propelled forward by arranging the two rudder plates as a rudder plate with a camber formed inside in the flow toward the hull center direction at the stern part. Thrust can be generated. For example, by increasing the front width of the two rudder plates with respect to the rear width and tilting them between 0 degrees and 10 degrees with respect to the hull center line, it becomes an optimum rudder plate with little resistance to increase in lift, A large rudder thrust can be obtained.

According to a third aspect of the present invention, in the two-rudder system according to the first or second aspect, when further turning performance is required, the driving means so that the angle of the other rudder plate is different from the rudder angle. It operates by. According to the third aspect of the present invention, for example, after making one rudder plate close to the hull, the other rudder plate can be further driven to generate a large lateral force on the hull. To improve .

The present invention 請 Motomeko 4 wherein, in the two rudder system according to any one of claims 1 to 3, one end of the drive shaft is supported by propeller guard disposed below the propeller extending from the hull It is characterized by that. According to the fourth aspect of the present invention, the strength against the load from the steering plate can be increased by supporting the drive shaft at both ends. It is also possible to connect the lower ends of the rudder plates and use that portion as a propeller guard so that the propeller does not come into contact with the seabed or drifting objects.

In the ship equipped with the two-rudder system corresponding to this invention of Claim 5 , the ship was equipped with the two-rudder system in any one of Claims 1-4 . According to the fifth aspect of the present invention, a low fuel consumption ship using rudder thrust can be realized.

The present invention described in claim 6 is a ship equipped with the dual rudder system according to claim 5 , wherein the ship is enlarged with a square coefficient of 0.7 or more or a length-width ratio (L / B) of 5 or less. It is a ship. According to the sixth aspect of the present invention, in the enlarged ship where the stern flow is unstable, the propulsion performance can be improved and the fuel consumption can be reduced by the rudder thrust.

The present invention of claim 7, wherein, in the ship equipped with the two rudder system of claim 5 or claim 6, the stern portion which is located below the upper end of the rudder blade, substantially the width of the hull center line It has the same two-dimensional shape, or a shape that acts like a flap because the gap between the front part of one rudder plate and the hull is reduced during steering with the rudder plate close to the hull. . According to the seventh aspect of the present invention, at the time of steering with one rudder plate close to the hull, the gap between the rudder plate and the hull is made as small as possible to enhance the flap effect, and the other rudder plate is further steered. The turning force can be improved by taking a large angle and acting like a guide vane.

The present invention according to claim 8 is a ship equipped with the dual rudder system according to any one of claims 5 to 7 , wherein the distance from the rear end of the stern tube to the rear end of the stern It is characterized by being 3% or less with respect to the length. According to the present invention as set forth in claim 8 , the propeller can be positioned rearward, the water line shape can be made longer than that of the conventional ship, and the stern shape of the stern part can be made less stern. Can be increased.

  According to the present invention, the rudder plate can generate a stern flow rectification effect, improve the propeller efficiency by reducing the flow, and generate a rudder thrust. It can function as an energy saving device. Moreover, the braking distance of a ship can be shortened because two rudder plates operate | move to a mutually opposing direction.

  In addition, when the two rudder plates are configured to generate thrust for propelling the hull forward by the effect of camber due to contraction of the stern part of the hull, or the angle of attack effect on the flow of the stern part, By increasing the front width of the two rudder blades relative to the rear width and tilting them from 0 degrees to 10 degrees with respect to the hull center line, it becomes an optimum rudder with little resistance to increased lift, and a large rudder Thrust can be obtained.

Further, when the driving means is operated so that the angle of the other rudder plate is different from the rudder angle, for example, after the one rudder plate is brought close to the hull, the other rudder plate is further driven to greatly increase the hull. Lateral force can be generated, and turning performance is further improved .

Also, one end of the drive shaft by two ends supporting the drive shaft when supported by the propeller guard disposed below the propeller extending from the hull, it is possible to enhance the strength against a load from the steering plate.

  Further, according to the present invention, when the ship is equipped with a two-rudder system, a low fuel consumption ship using rudder thrust can be realized.

  In addition, when the ship is an enlarged ship having a square coefficient of 0.7 or more or a length-width ratio (L / B) of 5 or less, in the enlarged ship where the stern flow is unstable, the propulsion performance is improved. Fuel consumption can be reduced by rudder thrust.

  In addition, the stern portion located below the upper end of the rudder plate has a two-dimensional shape with the same width from the hull center line, or one rudder plate at the time of steering with the rudder plate close to the hull. When the shape is such that the gap between the front and the hull is reduced and acts like a flap, when steering with one rudder plate close to the hull, the gap between the rudder plate and the hull is made as small as possible to achieve the flap effect. While increasing, the turning angle of the other rudder plate can be further increased, and the turning force can be improved by acting like a guide vane.

  In addition, if the distance from the rear end of the stern tube to the stern rear end of the hull is 3% or less with respect to the length of the hull, the propeller can be positioned rearward, compared to the conventional ship. Thus, the waterline shape can be lengthened, and the stern shape with less resistance can be obtained, or the hold capacity of the stern portion can be increased.

The principal part side surface block diagram which shows the ship equipped with the two-rudder system by one Embodiment of this invention Plan view of the main part of the ship FIG. 2 is a main part plan view showing a state during steering. A graph showing the results of an aquarium experiment using a model ship equipped with a twin rudder system according to this embodiment as a large-sized enlarged ship A graph showing the horsepower reduction rate of a model ship equipped with the same two-rudder system versus a model ship equipped with a normal rudder Explanatory drawing showing the improvement of the hull when equipped with the two-rudder system Principal configuration diagram showing other improvements to the hull when equipped with the two-rudder system Explanatory drawing showing further improvements of the hull when equipped with the two-rudder system The principal part side surface block diagram which shows the ship equipped with the two-rudder system by other embodiment of this invention The principal part plane block diagram which shows the ship equipped with the two-rudder system by further embodiment of this invention. The principal part plane block diagram which shows the state at the time of steering in FIG. The principal part plane block diagram which shows the ship equipped with the two-rudder system by further embodiment of this invention. The principal part plane block diagram which shows the state at the time of steering in FIG. The principal part block diagram which shows the ship equipped with the two-rudder system by other embodiment of this invention. Flow chart showing a design method for applying a two-rudder system to an existing ship

Below, the ship equipped with the two-rudder system by embodiment of this invention is demonstrated.
1 is a side view of a main part of a ship equipped with a twin rudder system according to the embodiment, FIG. 2 is a plan view of a main part of the ship, and FIG. 3 is a main part of FIG. FIG.

The ship according to the embodiment of the present invention drives the propeller 20 attached to the rear end 12 of the stern tube 11 of the hull 10, the two rudder plates 30, and the two rudder plates 30 via the drive shaft 40. Means 50 are provided.
The two rudder plates 30 are arranged on the side of the propeller 20, and a camber (difference between the chord and the center line) 31 is formed inside the two rudder plates 30. The two rudder plates 30 may be disposed in front of the propeller 20 as will be described later.

  The drive shaft 40 is disposed ahead of the center of the rudder plate 30 in the front-rear direction. As shown in FIG. 2, when the length in the front-rear direction of the rudder plate 30 is E, the drive shaft 40 is located at a position from the front end of the rudder plate 30 to 1 / 2E, more preferably 1 from the front end of the rudder plate 30. / 3E up to 3E. Thus, the steering plate 30 can be operated with a small driving load by disposing the drive shaft 40 ahead of the center of the steering plate 30 in the front-rear direction.

According to the present embodiment, the two rudder plates 30 are arranged on the side of the propeller 20 and the camber 31 is formed on the inner side of the two rudder plates 30, so that the rudder plate 30 causes the stern flow. A rectifying effect can be produced and the flow can be reduced to generate rudder thrust.
The two rudder plates 30 have a shape that generates thrust to propel the hull 10 forward by the effect of the camber 31 that reduces the flow of the stern portion of the hull 10. The shape for generating the thrust for propelling the hull 10 forward is, for example, that the front width A of the two rudder plates 30 is made larger than the rear width B, and is tilted from 0 degrees to 10 degrees with respect to the center line of the hull 10. Thus, an arrangement having an appropriate angle of attack with respect to the flow of the stern portion of the hull 10 can be secured, the propeller efficiency is increased, and the optimum rudder plate 30 with less resistance to the increase in lift is obtained, and a large rudder thrust is obtained. Can be obtained.

The distance D from the rear end 12 of the stern tube 11 to the stern rear end portion 13 of the hull 10 usually exceeds 3.5% with respect to the length (Lpp) of the hull 10, but in this embodiment, two The steering plate 30 is arranged in front of or on the side of the propeller 20 and the camber 31 is formed inside the two steering plates 30 to increase the size of the steering plate 30 in order to improve the steering force. Because there is no need
It can be 3% or less. For this reason, the stern portion of the hull 10 can be shifted rearward, and the stern portion can be formed into an elongated shape with little resistance, or the volume of the hold of the stern portion can be increased.

As shown in FIG. 3, the two rudder plates 30 are connected by the connecting means 32, and the two rudder plates 30 are operated at the same angle by the driving means 50 via the drive shaft 40. By operating the two rudder plates 30 at the same angle by the driving means 50, the rudder plate 30 can be operated stably, and can be driven by one driving means 50.
At the time of steering, it is preferable that one rudder plate 30 is brought into contact with the hull 10 to eliminate a gap between the front end of the rudder plate 30 and the hull 10.

FIG. 4 is a graph showing the results of an aquarium experiment using a model ship equipped with a twin rudder system according to the present embodiment as a large enlarged ship.
In FIG. 4, a model ship equipped with the two-rudder system according to the present embodiment and a model ship equipped with a normal rudder are compared with the propeller thrust (kg) on the horizontal axis and the rudder thrust (kg) on the vertical axis. Yes.
The model ship used here has a vertical length (Lpp) of 225 m, a ship width (B) of 48.8 m, a square factor (Cb) of 0.8, and a draft depth (d) of 13.4 m. did.

In the model ship equipped with the twin rudder system according to the present embodiment, a thrust of 7 to 8% of the propeller thrust is generated when the propeller thrust is in the range of 1.300 to 1.500 kg. On the other hand, a model ship equipped with a normal rudder has a hull resistance of about 6%.
Therefore, the model ship equipped with the two-rudder system according to this embodiment has a horsepower saving of 15% or more compared to the model ship equipped with the normal rudder.

FIG. 5 compares the model ship equipped with the same two-rudder system as in FIG. 4 with the model ship equipped with the normal rudder, and the horsepower reduction of the model ship equipped with the two-rudder system with respect to the model ship equipped with the normal rudder. In this graph, the horizontal axis represents boat speed (knots), the left vertical axis represents horsepower (kw), and the right vertical axis represents horsepower reduction rate (%).
As the boat speed increases, the horsepower reduction rate of the model ship equipped with the two-rudder system for the model ship equipped with the normal rudder increases. If the ship speed during actual navigation is 14.5 knots, the horsepower reduction rate is about 12%. If the ship speed during actual navigation is 16.5 knots, the horsepower reduction rate is about 15%.

  As shown in FIGS. 4 and 5, when a two-rudder system is installed in a ship, a low fuel consumption ship using rudder thrust can be realized.

FIG. 6 is an explanatory view showing an improvement of the hull in the case where the two-slewing system according to the embodiment of the present invention is equipped.
In FIG. 6, the propeller axis line of the hull 10 of the present embodiment, the rudder plate upper end line of the hull 10 of the present embodiment, the propeller axis line of the hull of the normal rudder ship, and the rudder plate of the hull of the normal rudder ship The top line is shown. In addition, the rudder plate upper end line of the hull of a normal rudder ship is set to the same height as the rudder plate upper end line of the hull 10 of the present embodiment.

  When equipped with the two-wheel rudder according to the present embodiment, the propeller 20 can be moved to the rudder position of the normal rudder ship. Therefore, compared with a normal rudder ship, the stern can be elongated and the hull resistance can be reduced and the performance can be greatly improved.

FIG. 7 is a main part configuration diagram showing another improvement of the hull in the case of being equipped with a twin rudder system according to an embodiment of the present invention. In FIG. 7, only a part of the rudder plate 30 and the stern part 14 are shown, and other configurations are omitted for convenience of explanation.
In the present embodiment, the stern portion 14 positioned below the upper end of the rudder plate 30 has a two-dimensional shape having substantially the same width from the hull center line. That is, the stern part line 14a in the upper end line of the rudder plate 30 and the stern part line 14b in the lower end line of the rudder plate 30 have a hull shape that is substantially matched in plan view.

  In this way, the stern portion 14 positioned below the upper end of the rudder plate 30 has a two-dimensional hull shape that does not have an angle in the vertical direction or has a small angle, so that one rudder plate At the time of steering with 30 close to the hull 10, the rudder between one rudder plate 30 and the hull 10 (stern part 14) is eliminated, and one rudder plate 30 acts like a flap, thereby further increasing rudder thrust. be able to.

FIG. 8 is an explanatory view showing still another improvement of the hull in the case where the two-rudder system according to the embodiment of the present invention is installed.
The ship shown in FIG. 8 shows the hull 10 having a vertical length (Lpp) of 300 m, a ship width (B) of 65 m, and a draft depth (d) of 17.9 m.
In a normal rudder ship, the distance Da from the rear end 12a of the stern tube 11 to the stern rear end 13 of the hull 10 is 14 m or more, which is 4.7% with respect to the length of the hull 10 (Lpp = 300 m). is there.

When equipped with the twin rudder system according to the embodiment of the present invention, the distance Db from the rear end 12b of the stern tube 11 to the stern rear end portion 13 of the hull 10 can be 9 m or less. It can be 3% or less with respect to the length (Lpp = 300 m).
Thus, the propeller 20 is positioned rearward by setting the distance Db from the rear end 12b of the stern tube 11 to the stern rear end 13 of the hull 10 to 3% or less with respect to the length of the hull 10. The water line shape can be made longer than that of conventional ships. Or it becomes possible to increase the volume of the hold of a stern part.

FIG. 9 is a side view of a main part showing a ship equipped with a two-rudder system according to another embodiment of the present invention. The same components as those in FIG.
The ship equipped with the two-rudder system according to the present embodiment supports one end 41 of the drive shaft 40 with a propeller guard 60 that extends from the hull 10 and is disposed below the propeller 20. In this embodiment, the configuration is the same as in FIGS. 2 and 3 except that it is supported by the propeller guard 60, and performs the same operation.

  According to the present embodiment, the strength against the load from the steering plate 30 can be increased by supporting the drive shaft 40 at both ends.

FIG. 10 is a plan view of a principal part showing a ship equipped with a two-rudder system according to still another embodiment of the present invention, and FIG. 11 is a plan view of a relevant part showing the state during steering in FIG. The same components as those in FIGS. 1 to 3 are denoted by the same reference numerals, and description thereof is omitted.
The ship equipped with the two-rudder system according to the present embodiment has the same configuration as FIG. 1 except that the two rudder plates 30 are arranged in front of the propeller 20, and performs the same operation.

  According to the present embodiment, the two rudder plates 30 are arranged in front of the propeller 20 and the camber 31 is formed inside the two rudder plates 30, so that the stern flow is rectified by the rudder plate 30. An effect can be produced and the flow can be reduced to generate rudder thrust.

As shown in FIGS. 1 to 3, when the two rudder plates 30 are arranged on the side of the propeller 20, the rudder thrust increases, and as shown in FIGS. 10 and 11, the two rudder thrusters are used. When the plate 30 is arranged in front of the propeller 20, the propulsion performance (course stability) tends to be further increased.
Depending on whether the rudder thrust or propulsion performance is emphasized, and the necessity of increasing the water line shape or increasing the volume of the hold, the two rudder plates 30 are arranged from the side of the propeller 20. It can be placed at any position in front.

FIG. 12 is a plan view of a principal portion showing a ship equipped with a two-rudder system according to still another embodiment of the present invention, and FIG. 13 is a plan view of a principal portion showing a state during steering in FIG. The same components as those in FIGS. 1 to 3 are denoted by the same reference numerals, and description thereof is omitted.
The ship equipped with the two-rudder system according to the present embodiment has the same configuration as that shown in FIGS. 1 to 3 except that the two rudder plates 30 are provided with driving means 50a and 50b that can operate independently.
In the present embodiment, the two steering plates 30 can be independently driven by the driving means 50a and 50b. In FIG. 13, the driving means 50b performs a larger operation on the steering plate 30 than the driving means 50a. Shows the case of giving.

According to the present embodiment, for example, after one rudder plate 30 is brought close to the hull 10, the other rudder plate 30 can be further driven to generate a large lateral force on the hull 10, and the turning performance is improved. improves. Moreover, according to this Embodiment, the braking distance of a ship can be shortened by opening and closing the two rudder plates 30 in the opposite direction. Also, the two rudder plates 30 can be arbitrarily driven independently by the driving means 50a, 50b according to the flow state of the stern part and the ship maneuvering situation of the hull 10.
In a ship equipped with a two-rudder system according to the present embodiment, particularly in an enlarged ship having a square coefficient of 0.7 or more or a length-width ratio (L / B) of 5 or less, the propulsion performance is improved and the rudder thrust is used. Low fuel consumption can be achieved.

FIG. 14 is a main part configuration diagram showing a ship equipped with a twin rudder system according to still another embodiment of the present invention. The same components as those in FIGS. 1 to 3 are denoted by the same reference numerals, and description thereof is omitted.
The ship equipped with the two-rudder system according to the present embodiment has two rudder plates 30 that are widened to open outwardly at the rudder plate upper end portion 30a with respect to the rear width, and at the rudder plate lower end portion 30b. The configuration is the same as that shown in FIGS. 1 to 3 except that the front width and the rear width are the same and substantially parallel to the center line of the hull 10.
In the rudder plate upper end portion 30a, the front width is increased with respect to the rear width so that the rudder plate 30 is opened outward. It has the effect of optimizing the angle of attack.
Further, in the rudder plate upper end portion 30a, increasing the front width with respect to the rear width to open outward accelerates the flow of the stern portion that is relatively slower above the central axis of the propeller 20, and further increases the rudder thrust and Propeller thrust can be increased. Further, the rudder plate lower end 30b has the same front width and rear width and is substantially parallel to the center line of the hull 10, thereby accelerating the relatively fast stern portion below the central axis of the propeller 20. Without rubbing, the rudder thrust can be obtained after balancing with the upper side, and can be applied to the propeller.
In a ship equipped with a two-rudder system according to the present embodiment, rudder thrust and propeller efficiency can be further increased.

  In addition, it is also possible to obtain thrust and the same turning force as the rudder plate 30 by constituting the two rudder plates 30 in the shape of two fins or in the form of a duct extending on both sides of the propeller 20. In this case, fins and ducts are included in the broad definition of the two rudder plates 30. Moreover, it is possible to combine the original two rudder plates 30 with fin-like or duct-like appendages to further increase the thrust and turning force.

Below, the design method of the two-rudder system by this Embodiment with respect to the existing ship is demonstrated.
FIG. 15 is a flowchart showing a design method for applying a two-rudder system to an existing ship.
First, the two rudder plates 30 are moved to the front or side of the propeller 20 (step 1). In step 1, the position of the propeller 20 may be moved in the direction of the stern rear end portion 13 of the hull 10 together with the two rudder plates 30 thereafter.
Next, if possible, the stern portion 14 positioned below the upper end of the rudder plate 30 is corrected to a two-dimensional hull shape that does not have an angle in the vertical direction (step 2).
After step 1 or after step 2, the two rudder plates 30 are designed in a shape along the contracted flow by the hull 10 (step 3).
After step 3, the camber 31 of the two rudder plates 30 is modified and designed so that the maximum thrust is generated by propeller contraction (step 4).
After step 4, interference between the rudder plate 30 and the hull 10 during steering is confirmed (step 5).
If there is a problem in step 5, the process returns to step 1 to change the position of the rudder plate 30.

With the above design method, the two-rudder system according to the present embodiment can be applied to an existing ship.
As described above, according to the present embodiment, the two rudder plates 30 can produce a flow rectifying effect of the flow of the stern portion 14 and reduce the flow to generate thrust by the rudder plate 30. The rudder plate 30 can be made to function not only as an original rudder function but also as an energy saving device.

  The present invention is suitable for large-sized enlarged ships such as ore carriers and oil tankers, but can also be applied to small ships.

DESCRIPTION OF SYMBOLS 10 Hull 11 Stern tube 12 Rear end 13 Stern rear end 14 Stern 14a Stern line 14b Stern line 20 Propeller 30 Rudder plate 31 Camber 32 Connection means 40 Drive shaft 50 Drive means

Claims (8)

A two-rudder system comprising two rudder plates arranged on the side of a propeller attached to the rear end of a stern tube of a hull and driving means for driving the two rudder plates via a drive shaft. A camber is formed inside the two rudder plates, and the two rudder plates can be driven independently by the driving means, and the two rudder plates are arranged on the rudder plate when not turning. The front part is arranged behind the end of the stern part of the hull located below the upper end of the rudder plate and ahead of the propeller, and the drive shaft is positioned in the front-rear direction with respect to the hull. arranged propeller substantially the same position, as well as operate in the same steering angle in the same direction by said driving means such that the front portion of one of the rudder blade during turning approaches the stern section, to each other by the drive means during braking Characterized by moving in the opposite direction Single rudder system. The two sheets of the rudder plate, the effect of the camber by contraction flow of the stern portion of the hull, or the effect of angle of attack to the flow of the stern portion that has a configuration for generating thrust to propel the hull forward The two-rudder system according to claim 1, wherein:   The two-rudder system according to claim 1 or 2, wherein when the turning performance is further required, the driving means is operated so that an angle of the other rudder plate is different from the rudder angle. . Two rudder system according to any one of claims 1 to 3, characterized in that the support with a propeller guard extends one end of said drive shaft from said hull is arranged below the propeller. A ship equipped with a twin rudder system, wherein the two rudder system according to any one of claims 1 to 4 is equipped on a ship. The ship equipped with the twin rudder system according to claim 5 , wherein the ship is an enlarged ship having a square coefficient of 0.7 or more or a length-width ratio (L / B) of 5 or less. The stern portion positioned below the upper end of the rudder plate has a two-dimensional shape with substantially the same width from the hull center line, or one of the above-mentioned ones during steering with the rudder plate close to the hull The ship equipped with the two-rudder system according to claim 5 or 6 , characterized in that a gap between the front portion of the rudder plate and the hull is reduced and acts as a flap. Wherein the distance from the rear end of the stern tube to the stern trailing end of the hull, to any one of claims 7 to claim 5, characterized in that it has 3% or less with respect to the length of the hull A ship equipped with a two-rudder system.