JP2017024643A - Wind pressure resistance reduction device of ship and ship having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wind pressure resistance reduction device of a ship which is applicable to any ship regardless of whether it is new or existing, can reduce wind pressure resistance acted on a cargo handling device with a simple configuration when receiving oblique head wind, and thus can effectively reduce wind pressure resistance of the entire ship, and a ship having the same.SOLUTION: In a side part of a hull 2, a windbreak side guard 21 having an inclined surface part 21a inclined so as to extend from a side part upper edge of the hull in a direction toward the upper side of a cargo handling device 15 is provided. A bow windbreak dome 22 extending from a bow upper edge in a direction toward the upper side of the cargo handling device 15 is provided in a bow of the hull 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an apparatus for reducing wind pressure resistance of a ship, and more particularly to an apparatus for reducing wind pressure resistance caused by an oblique head wind of a ship equipped with a cargo handling device on an upper deck, and a ship including the same.

  In addition to the viscous pressure resistance and viscous frictional resistance of water below the surface of the water, the resistance component of a vessel while navigating includes wave resistance by generating waves on the surface of the water. And the wind pressure resistance acting on the fittings is also a resistance that cannot be ignored. Therefore, in order to improve the propulsion performance of the ship and reduce fuel consumption, it is also important to reduce the wind pressure resistance of the ship during navigation.

There are roughly the following three methods (a) to (c) as methods for reducing wind resistance of a ship.
(A) Method of reducing wind pressure resistance acting on the superstructure including the residential area (b) Method of reducing wind pressure resistance of the hull itself (c) Method of reducing wind pressure resistance acting on the cargo handling device on the upper deck

In the method (a), a long box-shaped appendage is attached to a wing part protruding in the ship width direction from a residential area or a support part that supports the wing part from below, so that the wing during navigation There is one in which the wind pressure resistance received by the support part and the support part is reduced (for example, see Patent Document 1).
Further, in a ship provided with an upper structure, the upper structure has a first structure portion and a second structure portion arranged so as to be adjacent to the stern side of the first structure portion, By disposing the both side surfaces of the second structure portion in the ship width direction outside the both side surfaces of the first structure portion in the ship width direction, the ship width is peeled off in the vicinity of both side portions of the first structure portion. In some cases, wind pressure flowing in the stern side while spreading in the direction is made to flow smoothly along the outer shape of the upper structure to reduce the wind pressure resistance generated in the upper structure (for example, see Patent Document 2). ).

As the method of (b), in the wood chip carrier, the vertical cross-section bow shape is a straight shape that rises toward the stern starting from an arbitrary position above the inundation line, and an inclined shape in which the inclination angle changes in the middle Alternatively, there is one in which the wind pressure resistance with respect to the hull bow is reduced by forming it in a streamline shape (see, for example, Patent Document 3).
Further, in the liquefied gas carrier ship, the wind that flows from the bow side toward the stern side along the upper surface of the tank cover that covers the upper half of the plurality of spherical tanks arranged along the stern direction, In some cases, the wind pressure resistance received by the front of the residential area is reduced by installing fins that change the wind direction ahead of the front of the residential area so that it does not directly hit the front of the house (for example, (See Patent Document 4).

  As the method (c), in a ship provided with a cargo handling crane and the horizontal section of the rotary post of the cargo handling crane is formed in a polygonal shape, it becomes the bow side of the rotary post when the cargo handling crane is stored in a jib during navigation. By installing a wind pressure reduction cover with a horizontal cross-sectional shape covering the corner of the rotating post in an arc shape, elliptical shape or streamline shape at the site, the vortex generated at the corner of the rotating post is reduced. In some cases, the wind pressure resistance of the rotating post is reduced to reduce the wind pressure resistance of the entire ship (see, for example, Patent Document 5).

JP2013-14192A JP 2014-148282 A JP 2014-80095 A JP 2010-58577 A JP 2012-71696 A

By the way, in a ship in which a plurality of cargo handling devices such as deck cranes and hoppers are installed on the upper deck of the hull (for example, a bulk carrier with cargo gear or a wood chip carrier), a plurality of protrusions protrude on the upper deck of the hull. The ratio of the wind pressure resistance acting on the cargo handling device in the wind pressure resistance of the entire ship is large.
For this reason, even if the technology according to Patent Documents 1 and 2 is applied to a ship in which a cargo handling device is installed on the upper deck of the hull, that is, an appendage is attached to the upper structure including the residential area, or the upper structure Even if the shape of the ship is changed, there is a problem that the wind pressure resistance of the entire ship cannot be effectively reduced because of the large influence of the wind pressure resistance received by the cargo handling device.
Further, when the technique according to Patent Document 3 is applied to change the hull shape, a large arrangement change is required, and there is a concern that design changes, construction, or remodeling may cause great costs.
Moreover, the technique which concerns on the said patent document 4 is a technique which can be applied specially to a liquefied gas carrier ship, and cannot be applied to the ship by which the cargo handling apparatus, such as a deck crane, was installed on the hull upper deck. .
In addition, if the technique according to Patent Document 5 is applied and a wind pressure reduction cover is provided at a portion on the bow side of the rotating post of the cargo handling crane, the wind pressure resistance that the rotating post receives is surely reduced. Although it is possible, the wind pressure resistance received by other parts cannot be reduced, and since the technology cannot be applied to a cargo handling device such as a hopper other than a cargo handling crane, various cargo handling devices and the entire ship receive. There is a problem that the wind pressure resistance cannot be effectively reduced.

  In addition, when a wind heading obliquely blows against a ship equipped with multiple cargo handling devices, wind pressure acts on each cargo handling device, so depending on the wind direction angle of the diagonally facing wind, the wind pressure resistance is greater than when the frontal wind blows. Is significantly increased, and it is desired to effectively reduce the wind pressure resistance when the cargo handling apparatus receives a slanting wind.

  The present invention has been made in view of the above-described problems, and can be applied to any newly installed or existing ship, and reduces wind pressure resistance acting on a cargo handling device when receiving a headwind obliquely with a simple configuration. Therefore, it is an object of the present invention to provide a ship wind pressure resistance reduction device that can effectively reduce the wind pressure resistance of the entire ship, and a ship including the same.

In order to achieve the above object, a ship wind pressure resistance reducing device according to the first invention comprises:
A wind pressure resistance reduction device for a ship in which a required cargo handling device is installed on the upper deck of the hull,
A windproof side guard having an inclined surface portion that is inclined so as to extend in a direction toward an upper side of the cargo handling device from an upper edge of the side portion is disposed on a side portion of the hull (first invention). ).

  In the ship wind pressure resistance reducing apparatus according to the first aspect of the present invention, it is preferable that a bow windproof dome extending in a direction from the upper edge of the bow toward the upper side of the cargo handling apparatus to cover the bow is disposed on the bow of the hull (first). 2 invention).

Next, the ship according to the third invention is
A ship with the required cargo handling equipment installed on the upper deck of the hull,
It is provided with the wind pressure resistance reduction apparatus of the ship which concerns on 1st invention or 2nd invention.

  According to the ship wind pressure resistance reducing device of the first aspect of the invention, the wind direction is such that an obliquely directed wind blowing toward the cargo handling device during navigation flows from the upper edge of the side of the hull to the upper side of the cargo handling device by the inclined surface of the windproof side guard. Since it is induced, it is possible to reduce the wind pressure resistance acting on the cargo handling device when receiving an obliquely headed wind, thereby effectively reducing the wind pressure resistance of the entire ship. Such an effect is achieved by a simple configuration in which a windproof side guard having an inclined surface that is inclined so as to extend in a direction from the upper edge of the side of the hull toward the upper side of the cargo handling device is provided on the side of the hull. It can be applied to both new and existing ships.

  Further, by adopting the configuration of the second invention, the wind direction is guided by the bow windproof dome so that an obliquely directed wind blowing toward the foremost cargo handling device during navigation flows from the upper edge of the hull to the upper side of the cargo handling device. Therefore, by adding the bow windproof dome, it is possible to obtain an effect of reducing wind pressure resistance more than the windproof side guard alone.

  According to the ship of the third invention, since the wind pressure resistance of the entire ship is effectively reduced by the wind pressure resistance reducing device for the ship according to the first or second invention, the propulsion performance of the ship can be improved. , Can reduce fuel consumption.

FIG. 1 is an overall perspective view of a wood chip carrier according to an embodiment of the present invention. FIG. 2 is a front view showing a part of the timber chip carrier, with (a) showing a mode example in which windproof side guards are directly installed on the side of the hull, and (b) showing the side of the hull. It is a figure which shows the example of an aspect which installs a wind-proof side guard through a standing plate member. FIG. 3 is a side view of the front portion of the wood chip carrier. FIG. 4 is an explanatory diagram of the set coordinate system of the ship. Fx represents the longitudinal force due to the wind, Uw represents the wind speed, and φ represents the wind direction angle. FIG. 5 is a side view of five types of ships. FIG. 6 is a graph showing the relationship between the wind pressure resistance coefficient and the wind direction angle. FIG. 7 is a front view showing a part of a ship provided with four types of windproof side guards and a bow windproof dome, broken away. FIG. 8 is a graph showing the relationship between the wind pressure resistance coefficient and the height ratio of the windproof side guard.

  Next, a specific embodiment of a ship wind pressure resistance reducing apparatus and a ship including the same according to the present invention will be described with reference to the drawings. The embodiment described below is an example in which the present invention is applied to a wood chip carrier, but of course the invention is not limited to this, and can also be applied to a ship such as a bulk carrier with a cargo gear. It is suitable to be applied to a ship having a form in which a cargo handling device is installed like a large protrusion on the upper deck.

<Overview of wood chip carrier>
A wood chip carrier 1 shown in FIG. 1 includes a hull 2, four hoppers 3, 4, 5, 6 and three deck cranes 7, 8, 9 installed on the upper deck of the hull 2, and a hull. 2 and an upper structure 10 including a residential area installed on the upper deck.
The four hoppers 3 to 6 and the three deck cranes 7 to 9 are alternately arranged at predetermined intervals from the vicinity of the bow to the vicinity of the stern residence area with the hopper 3 at the top, and the upper part behind the last hopper 6. Structure 10 is arranged.
Between each hopper 3-6 and each deck crane 7-9, the cargo hold which has the hatch cover 11a exposed on the upper deck of the hull 2, and is a accommodating part of the wood chip which is a load inside the hull 2 11 is arranged.
The hoppers 3 to 6 and the deck cranes 7 to 9 correspond to the “loading device” of the present invention. Hereinafter, the hoppers 3 to 6 and the deck cranes 7 to 9 are collectively referred to as “loading device 15”. I will call it.

<Explanation of wind resistance reduction device>
Furthermore, the wood chip carrier 1 is provided with a wind pressure resistance reducing device 20 for reducing the wind pressure resistance received during navigation. The wind pressure resistance reduction device 20 includes a windproof side guard 21 and a bow windproof dome 22 that reduce wind pressure resistance caused by an obliquely directed wind.

<Explanation of windproof side guard>
The windproof side guards 21 are respectively disposed on both sides of the hull 2 and are constituted by strip plate-like members extending from the vicinity of the bow of the hull 2 to the entire area near the stern residence area.

By the way, in the case of an obliquely directed wind, wind pressure acts on each of the plurality of cargo handling devices 15, that is, the four hoppers 3 to 6 and the three deck cranes 7 to 9, so depending on the angle of the obliquely directed wind, The wind pressure resistance tends to be significantly larger than the case (particularly when the wind direction angle is around 20 °).
Windproof side guards 21 are installed so that all four hoppers 3 to 6 and three deck cranes 7 to 9 are shielded in a side view so that the obliquely facing wind does not directly hit all the cargo handling devices 15. It is possible to do.

  However, if the windproof side guard 21 is installed in such a manner, the windproof side guard 21 receives the obliquely directed wind and the wind pressure resistance is increased, and the load handling work by the deck cranes 7 to 9 is hindered.

Therefore, in the windproof side guard 21 of the present embodiment, as shown in FIG. 2A, (a) the arrangement height dimension h is not more than a certain regulation value that does not hinder the cargo handling work by the deck crane 7. And (b) the hull 2 from the vertical direction toward the center line S of the hull 2 along the virtual line L extending in the direction toward the upper side of the deck crane 7 from the vicinity of the upper side edge (ship edge) of the hull 2 An inclined surface portion 21a is formed so as to be inclined inward so as to extend from the upper edge of the side portion of the hull 2 so as to dodge or squeeze the top of the deck crane 7. And by the inclined surface 21a, the wind direction is changed and deflected so that the obliquely directed wind does not hit all the cargo handling devices 15.
In addition, as shown in FIG. 2B, there is also a mode in which the windproof side guard 21 of the present embodiment is continuously provided via a rising plate-like member 23 that is installed so as to extend in the vertical direction at the side of the hull 2. possible. In this case, the upper end edge of the rising plate-like member 23 becomes the upper side edge of the hull 2.

<Description of bow windproof dome>
As shown in FIG. 1 and FIG. 3, the bow windproof dome 22 is arranged at the bow of the hull 2, and is configured by a bent plate-like member that is formed in a partial ellipsoidal appearance so as to cover the bow. Yes.

  By the way, the wind pressure resistance due to the obliquely directed wind received by the leading hopper 3 installed at the position closest to the bow among the plurality of cargo handling devices 15, that is, the four hoppers 3 to 6 and the three deck cranes 7 to 9 is windproof. Since the bow portion is opened only by the side guard 21, it cannot be sufficiently reduced.

  For example, if the head hopper 3 is completely covered by looking at the bow side from an oblique front so that the head hopper 3 does not hit the head hopper 3 diagonally, the head hopper 3 can be prevented from hitting the head hopper 3 diagonally. It is speculated that the wind pressure resistance can be effectively reduced. However, the height of the bow wind-proof dome 22 is subject to certain restrictions in view of securing the forward visibility and rules, and the wind pressure resistance is reduced. You may not get the effect you want.

  Therefore, in the bow windproof dome 22 of the present embodiment, the height is set to a height not more than a certain regulation value that does not cause a problem in terms of ensuring forward visibility and from the upper edge of the bow toward the top of the leading hopper 3. By adopting a partially cone shape that spreads in the direction that extends in the direction, the wind direction resistance can be reliably obtained by changing the direction of the wind so that the obliquely directed wind does not hit the leading hopper 3. Yes.

<Description of effects>
In wood chips carrier 1 configured as described above, if the slant head wind is blowing at the time of sailing, oblique head wind flowing toward the plurality of handling devices 15, represented by the symbol Q _A white arrow in FIG. 2 As described above, since the wind direction is guided by the inclined surface 21a of the windproof side guard 21 so as to flow from the upper edge of the side of the hull 2 to the upper side of the cargo handling device 15, the wind pressure resistance of the cargo handling device 15 in the case of the diagonally facing wind is reduced. can do.
Further, in the wood chips carrier 1, if the oblique head wind is blowing at the time of sailing, oblique head wind flowing toward the front row handling apparatus 15 (the top of the hopper 3) is indicated by the symbol Q _B white arrows in FIG. 3 As described above, the wind direction is guided by the bow windproof dome 22 so as to flow from the upper edge of the bow of the hull 2 to above the leading hopper 3, so that the wind pressure resistance acting on the leading hopper 3 when receiving the heading obliquely is reduced. be able to.

  Therefore, according to the wood chip carrier 1 of the present embodiment, the wind pressure resistance acting on the cargo handling device 15 when receiving the obliquely directed wind is reduced by the wind pressure resistance reducing device 20 including the windproof side guard 21 and the bow windproof dome 22. This can be further reduced as compared with a single unit, and the wind pressure resistance of the entire ship can be reduced more effectively.

  Such operational effects are as follows: (a) a windproof side guard 21 having an inclined surface 21a that is inclined so as to extend from the upper edge of the side of the hull 2 toward the upper side of the cargo handling device 15 is provided on the side of the hull 2; And (b) a simple windbreak dome 22 extending from the upper edge of the bow toward the upper side of the foremost cargo handling device 15 and covering the bow is disposed at the bow of the hull 2. It can be applied to both new and existing ships.

  As mentioned above, although the wind pressure resistance reduction apparatus and ship of the ship of this invention were demonstrated based on one embodiment, this invention is not limited to the structure described in the said embodiment, In the range which does not deviate from the meaning The configuration can be changed as appropriate.

  Next, a specific embodiment of a ship wind pressure resistance reducing apparatus and a ship including the same according to the present invention will be described with reference to the drawings.

  The wind pressure characteristics acting on five types of ships as shown in FIGS. 5A to 5E were grasped by CFD (Computational Fluid Dynamics) calculation.

Here, the type 1 ship shown in FIG. 5A is a gearless ship in which only the upper structure 10 is mounted on the hull 2.
The type 2 ship shown in FIG. 2B is a conventional wood chip carrier ship in which the upper structure 10, the required hoppers 3-6 and the deck cranes 7-9 are mounted on the hull 2.
In the type 3 ship shown in FIG. 2C, the upper structure 10, the required hoppers 3-6 and the deck cranes 7-9 are mounted on the hull 2, and the present invention is installed on both sides of the hull 2. This is a wood chip carrier ship provided with such windproof side guards 21.
In the type 4 ship shown in FIG. 4D, the upper structure 10, the required hoppers 3-6 and the deck cranes 7-9 are mounted on the hull 2, and the bow of the hull 2 is attached to the present invention. This is a wood chip carrier ship in which the bow windproof dome 22 is arranged.
The type 5 ship shown in FIG. 5 (e) has the upper structure 10, the required hoppers 3-6 and the deck cranes 7-9 mounted on the hull 2, and the present invention is installed on both sides of the hull 2. The windproof side guard 21 is a wood chip carrier ship in which the bow windproof dome 22 according to the present invention is disposed on the bow portion of the hull 2.

FIG. 4 shows a case where each of the five types of ships shown in FIGS. 5A to 5E receives wind at a wind speed of 14.5 m / s in a range of wind direction angles of 0 ° to 180 °. CFD calculations were performed based on the coordinate system settings as shown. The comparison of the wind pressure resistance coefficient Cx obtained as a result is shown in the graph of FIG. 6 with the wind direction angle on the horizontal axis.
Regarding the wind direction angle, 0 ° indicates a completely headed wind (front-facing wind), greater than 0 ° and less than 90 ° indicates an obliquely directed wind, 90 ° indicates a crosswind, and greater than 90 ° and less than 180 ° indicates an oblique tailwind. 180 ° indicates complete tailwind.

The wind pressure resistance coefficient Cx is obtained by making the wind pressure resistance dimensionless and is expressed by the following equation.

  In the graph of FIG. 6, it shows that the wind pressure resistance due to the influence of the wind increases as the value of Cx increases toward the minus side, and conversely, as the value of Cx increases toward the plus side, This shows that the addition of propulsive force is increased.

  Both type 3 and type 5 vessels have reduced wind pressure resistance in the cargo handling device 15 as compared to type 2 vessels (conventional wood chip carrier), and in particular, type 2 vessels have peak wind pressure resistance. The wind pressure resistance near the wind direction angle of 20 ° showing the value is greatly reduced (type 3: about 30% reduction, type 5: about 40% reduction), and this is because the windproof side guard 21 effectively reduces the wind pressure resistance. It shows that it is due to the reduction.

  As is clear from the characteristics indicated by the curves relating to the type 3 and type 4 ships in the graph of FIG. 6, the windproof side guard 21 alone or the bow windproof dome 22 alone is 20 Wind pressure resistance in the case of an obliquely directed wind with a wind direction angle of -40 ° can be reduced by about 30% or about 15% compared to a type 2 ship, but a windproof side guard 21 and a bow windproof dome 22 are provided. Thus, as is clear from the characteristics shown by the curve for the type 5 ship in the graph of FIG. 6, the wind pressure resistance in the case of an obliquely directed wind with a wind direction angle of 20 ° to 40 ° is compared with that of the type 2 vessel. The wind resistance can be reduced by about 40%, and a wind pressure resistance reduction effect can be further obtained as compared with the case where the windproof side guard 21 or the bow windproof dome 22 is provided alone.

  The type 4 ship has a large propulsive force in a range where the wind direction angle is larger than 90 ° and less than 180 °. This indicates that the bow windproof dome 22 receives the oblique tailwind and adds a propulsive force to the ship at the time of the oblique tailwind.

<Wind pressure resistance reduction effect due to the shape of windproof side guard>
Next, as windproof side guards, those having four types of shapes and dimensions as shown in FIGS. 7A to 7D are prepared, and the four types of windproof side guards 25, 21, 21 A, and 21 B are provided. CFD calculation was performed for the case where the installed wood chip carrier received an oblique wind with a wind direction angle of 20 °. The comparison of the wind pressure resistance coefficient Cx obtained as a result is shown in the graph of FIG. 8 with the height ratio h / h1 of the windproof side guards 25, 21, 21A, 21B on the horizontal axis. Here, h1 represents the height of the type 2 windproof side guard 21 shown in FIG. 7 (b), and is the same height as the hatch cover 11a of the cargo hold 11. The hulls 2 each have a bow windproof dome 22 and perform CFD calculation.

  When the windproof dome 22 on the bow and the windproof side guard 25 of the curved shape shown in FIG. 7 (a) are installed against an obliquely directed wind with a wind direction angle of 20 °, the entire structure (upper structure, hull, cargo handling device) Although 13% wind pressure resistance reduction effect can be obtained, even if the size of the windproof side guard 21 is not extremely increased, the inclined surface portion 21a is formed as a flat plate shape, and on the extended line of the inclined surface portion 21a. It can be seen from the graph of FIG. 8 that the wind pressure resistance reduction effect is increased to 22% when the windproof side guard 21 is installed at such an angle that the top of the deck crane 7 is located. In the case of the type 1 windproof side guard 25 shown in FIG. 7A, a part of the wind flowing along the shape of the windproof side guard 25 flows downward and hits the hopper 3 or the like. In the case of type 2-4 inclined flat plate-shaped windproof side guards 21, 21A, 21B shown in FIGS. 7B to 7D, the amount of wind that flows straightly along the inclined surface portion 21a increases. This is because the wind pressure resistance received by the hopper 3 or the like is greatly affected.

  The wind pressure resistance reduction device and ship of the ship of the present invention can be applied to any newly installed or existing ship, and can reduce the wind pressure resistance acting on the cargo handling device when receiving an obliquely headed wind with a simple configuration. As a result, the wind pressure resistance of the entire ship can be effectively reduced, so that it can be suitably used for reducing wind pressure resistance of ships equipped with cargo handling devices. The potential is great.

DESCRIPTION OF SYMBOLS 1 Wood chip carrier 2 Hull 3-6 Hopper 7-9 Deck crane 10 Superstructure 11 Cargo hold 20 Wind pressure resistance reduction device 21 Windproof side guard 22 Bow windproof dome

In order to achieve the above object, a ship wind pressure resistance reducing device according to the first invention comprises:
A wind pressure resistance reducing device for a ship in which a plurality of cargo handling devices are installed on a deck between a bow and a stern of a hull,
A windproof side guard having an inclined surface portion that inclines so as to extend in the direction from the upper edge of the side portion toward the upper side of the cargo handling device is disposed on the side portion of the hull from the vicinity of the bow to the vicinity of the stern. (First invention).

Next, the ship according to the third invention is
A ship having a plurality of cargo handling devices installed on the deck between the bow and stern of the hull,
It is provided with the wind pressure resistance reduction apparatus of the ship which concerns on 1st invention or 2nd invention.

According to the ship wind pressure resistance reducing device of the first aspect of the invention, the wind direction is such that an obliquely directed wind blowing toward the cargo handling device during navigation flows from the upper edge of the side of the hull to the upper side of the cargo handling device by the inclined surface of the windproof side guard. Since it is induced, it is possible to reduce the wind pressure resistance acting on the cargo handling device when receiving an obliquely headed wind, thereby effectively reducing the wind pressure resistance of the entire ship. Such advantages are, over a windproof sideguard having an inclined surface inclined so as to extend in a direction towards the upper side of the cargo apparatus from the side upper edge of the hull from the bow near the definitive on the side of the hull to the entire area of the stern near It can be achieved with a simple configuration such as being installed, and can be applied regardless of whether it is a newly installed ship or an existing ship.

Claims (3)

A wind pressure resistance reduction device for a ship in which a required cargo handling device is installed on the upper deck of the hull,
An apparatus for reducing wind pressure resistance of a ship, comprising a windproof side guard having an inclined surface portion that is inclined to extend in a direction from an upper edge of the side portion toward an upper side of the cargo handling device on a side portion of the hull.   2. A wind pressure resistance reducing device for a ship according to claim 1, wherein a bow windproof dome extending from the upper edge of the bow toward the upper side of the cargo handling device and covering the bow is disposed at the bow of the hull. . A ship in which a required cargo handling device is installed on the hull,
A ship comprising the wind pressure resistance reducing device for a ship according to claim 1 or 2.

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