WO2023149280A1

WO2023149280A1 - Fin

Info

Publication number: WO2023149280A1
Application number: PCT/JP2023/002078
Authority: WO
Inventors: 勝慶熊野; 隆仁小池
Original assignee: 勝慶熊野; 有限会社Ｇファクトリー
Priority date: 2022-02-03
Filing date: 2023-01-24
Publication date: 2023-08-10

Abstract

Provided is a fin which is superior in both steering performance and rectilinearity of a board.　A fin 1C is to be attached to a back surface 2a side of a board 2. In the fin 1C, a core member 11 having high strength is arranged so as to be shifted to the board 2 side.

Description

fin

The present invention relates to fins attached to surfboards and the like.

A fin that acts as a rudder is attached to the back of the surfboard, etc., to stabilize the straightness and steering of the surfboard. With such fins, the overall shape of the fins and the ease of bending of the fins affect the straightness and steering performance of the surfboard. In particular, the bendability of the fins depends greatly on the hardness of the material that makes up the fins. Fins that are hard and hard to bend make it difficult to hold water and improve straightness, while soft and bendable fins hold water. It is known that steerability is improved by making it easier to move.

The fin of Patent Document 1 is made by laminating a thick core mat or the like having substantially the same shape as the fin between a pair of molds corresponding to the shape of the fin, applying polyester resin, and further glass fiber on the outside. It is obtained by laminating woven glass cloth or the like, applying a polyester resin, and curing it while applying pressure. A fin such as that disclosed in Patent Document 1 has a thick core mat or the like laminated inside the fin, so that the manufacturing process can be simplified as compared with a conventional fin manufactured by laminating 20 to 30 layers of glass cloth. Instead, the weight of the fin can be reduced while maintaining substantially the same thickness as the conventional fin.

Japanese Patent Application Laid-Open No. 62-246383 (pages 2-3, FIG. 1)

However, in the fin of Patent Document 1, a core mat or the like having substantially the same shape as the fin extends to the tip of the fin called a tip, and these are covered with glass cloth from the outside. Because the fins are hardened with polyester resin, they are excellent in straight running, but the fins as a whole are stiff and difficult to bend, making it difficult to hold water, resulting in poor steering performance.

The present invention has been made with a focus on such problems, and an object thereof is to provide a fin that is excellent not only in the straightness of the board but also in the steering performance.

In order to solve the above problems, the fin of the present invention is
A fin attached to the back side of the board,
The fin is characterized in that a core material having high strength is arranged biased toward the board.
According to this feature, the board side of the fin is less likely to bend due to fluid resistance when changing the direction of travel of the board, and the tip of the fin is easier to bend, so in addition to the straightness of the board, it has excellent steering performance. We can provide fins.

The core material is characterized in that it is arranged along the outline of the fin.
According to this feature, it is possible to create an intensity distribution that does not impede the original function of the fin.

The core material is characterized in that it extends to the legs of the fins attached to the back side of the board.
According to this feature, the legs can be reinforced by the core material.

The tip of the core material is positioned closer to the board than the vertex of the rear edge portion of the fin.
According to this feature, the tip side of the fin can be easily bent, and the steering performance of the board is improved.

It is characterized in that the rear end of the core member is located forward of the base point of the rear edge portion of the fin.
According to this feature, the rear end side of the fin can be easily bent, and the steering performance of the board is improved.

The core material is characterized by being a wire material.
According to this feature, the weight of the fin can be reduced.

The core material is characterized in that it is adhered to the base material.
According to this feature, the strength of the base material and the core material that constitute the fin can be enhanced.

It is a bottom view showing the surfboard in Example 1 of the present invention. It is the back view which looked at the surfboard from the tail side. 4 is a side view of a fin in Example 1. FIG. FIG. 4 is a cross-sectional view taken along the line AA of FIG. 3; (a) is a front view showing bending characteristics of a fin in Example 1, and (b) is a front view showing bending characteristics of a conventional fin. FIG. 11 is a side view of a fin in Example 2; FIG. 7 is a cross-sectional view taken along the line BB of FIG. 6; FIG. 11 is a side view of a fin in Example 3; FIG. 11 is a side view of a fin in Example 4; FIG. 10 is a diagram showing a method of manufacturing a fin in Example 5;

A form for implementing the fin according to the present invention will be described below based on an embodiment.

The fins according to Example 1 will be described with reference to FIGS. 1 to 5. FIG. 1 is the front side (front side) of the board, the right side of FIG. 1 showing the back side of the board is the left side of the board, and the left side of FIG. 1 is the right side of the board. The front end side of the board is sometimes called the nose side, and the rear end side is sometimes called the tail side.

The fins of the present invention are attached to the back side of the board. In this embodiment, the fins attached to the surfboard 2 as a board will be described, but the fins may be attached to other boards such as a bodyboard and a wakeboard.

As shown in FIGS. 1 and 2, on the tail side of the back surface 2a of the surfboard 2 of this embodiment, there are a center fin 1C positioned in the center in the left-right direction and positioned so as to sandwich the center fin 1C from left to right. A pair of

side fins

1L and 1R are provided.

The center fin 1C is arranged in the left-right center of the surfboard 2 so as to be substantially orthogonal to the back surface 2a. The

side fins

1L and 1R are arranged to be shifted forward from the center fin 1C. Specifically, the side fins 1L and 1R are inclined in the left-right direction away from each other toward the lower end, and are inclined in the left-right direction away from each other from the front end to the rear end. Although the surfboard 2 of the present embodiment has been described as having three

fins

1L, 1C, and 1R, the present invention is not limited to this, and the number and arrangement of fins may be freely changed.

Next, the structure of the center fin 1C will be explained. Note that the

side fins

1L and 1R are formed in a so-called flat foil in which the surface facing inward in the left-right direction is a flat surface and the surface facing outward in the left-right direction is a convex curved surface (see FIG. 2). , and the center fin 1C, the description thereof will be omitted.

As shown in FIG. 3, the center fin 1C (hereinafter also referred to as fin) of the first embodiment includes a base material 10 forming the outer shape of the fin and a base material 10 inside the base material 10 on the side of the surfboard 2, that is, above. and a core material 11 arranged to be biased to the side. It should be noted that the fins in this embodiment are thick on the front side and on the upper side, and the thickness gradually decreases toward the rear side and the lower side, so that the cross-sectional shape is streamlined (see FIG. 4). .

In this embodiment, the base material 10 is mainly made of polycarbonate, and has elasticity by adding an appropriate amount of glass powder. Moreover, the base material 10 is translucent and lightweight by using polycarbonate as a main material. The base material 10 of the present embodiment has an overall shape that gradually extends rearward from the base end side of the upper part toward the tip end side of the lower part. In particular, the rear edge portion 10a forming the rear outer edge of the base material 10 has an external shape extending rearward while gradually curving from the base point P1 of the upper end toward the apex P2 (the rearmost point) of the tip. there is

As long as the base material has the elasticity required for the fins, other synthetic resins such as polyester resins and silicon resins, rubber, etc. may be used as main materials other than polycarbonate, and fillers and various additives may be added. may be added.

In addition, in this embodiment, the base member 10 is integrally formed with two front and

rear leg portions

12, 12 protruding upward from a substantially horizontally extending base 10b constituting the upper end portion of the fin. The fins of this embodiment are attached to the back surface 2a of the surfboard 2 by inserting the

legs

12, 12 into a fin box 3 provided on the back surface 2a of the surfboard 2 and fixing them with bolts 4 (see FIG. 1). ). The shape of the leg portion is not limited to this embodiment, and for example, one leg portion extending in the front-rear direction of the base may be integrally formed.

In the present embodiment 1, the core material 11 is a single wire rod made of stainless steel and having a circular cross section (see FIG. 4). It is bent and formed. Note that the core material 11 is a wire rod having the same diameter over the entire length. The core material 11 is a different material from the base material 10 and has higher strength than the base material 10 . Specifically, the core material 11 is a member having a Young's modulus larger than that of the base material 10 , in other words, the core material 11 is a member that is harder than the base material 10 and bends less easily.

The core material may be made of other metal such as aluminum or titanium, synthetic resin, wood, bamboo, etc., other than stainless steel, as long as it has a higher strength than the base material. In addition, the core material may be made of the same material as the base material. For example, by adding a filler such as glass fiber or carbon fiber to the same material as the base material, the strength is increased compared to the base material. There may be.

In addition, the wire rod used as the core material is not limited to one having a circular cross-sectional shape. The cross-sectional shape of the wire used as the fin may be a flat plate shape that is short in the thickness direction of the fin. Moreover, the cross-sectional shape, cross-sectional area, and the like of the wire rod used as the core material may be partially changed according to the desired bending characteristics of the fin. For example, as described above, by adopting a flat plate-shaped cross-sectional leaf spring material that is short in the thickness direction of the fin as the core material, the elastic restoring force of the fin is improved and the bending characteristics of the fin are improved. can be greatly increased. Moreover, the wire rod used as the core material may have a hollow structure.

In addition, the core material 11 is arranged inside the base material 10 along the outer shape of the fins. Specifically, the core member 11 is bent along the outer shape of the fin, and the rear end 11a is located forward of the base point P1 of the rear edge portion 10a of the fin. That is, the core member 11 is bent so as to be positioned forward of the imaginary line α passing through the base point P1 and extending orthogonally to the base 10b of the fin. The rear end 11a of the core material 11 is a portion located at the rearmost end in the entire core material 11. As shown in FIG.

In addition, the tip 11b (lower end) of the core material 11 is located above the vertex P2 of the rear edge portion 10a of the fin. That is, the core member 11 is bent so that its tip 11b is positioned above the imaginary line β passing through the vertex P2 and extending parallel to the base 10b of the fin. Note that the tip 11b of the core material 11 is a portion located at the forefront (lowest end) in the entire core material 11 .

In addition, the core member 11 has both

upper ends

11c and 11d extending to the interior of the two front and

rear legs

12 and 12. In particular, the upper end portion 11 c on the front side has its end surface exposed to the upper surface 12 a of the leg portion 12 . The exposed portion of the core material 11 may be covered with the material of the base material 10, a caulking material, or the like.

Further, as shown in FIG. 4, the core material 11 is arranged substantially in the center of the fin in the thickness direction (horizontal direction). Further, the base material 10 is welded to the core material 11 . That is, the core material 11 is embedded in a state in which its outer surface is integrally adhered to the base material 10 .

A method for manufacturing the center fin 1C will now be described. In the present embodiment 1, the center fin 1C is a base that is heated and melted in the mold while the core material 11 is previously fixed and arranged substantially in the center in the thickness direction (horizontal direction) of the mold corresponding to the shape of the fin. It is manufactured by so-called insert molding in which the material of the material 10 is poured, cooled and solidified. Thereby, the base material 10 is welded to the core material 11 .

As described above, the core material 11 having a high strength is arranged in the fin so as to be biased toward the surfboard 2 side (upper side). According to this, as shown in FIG. 5(a), the bending characteristics of the fins of this embodiment are similar to the bending characteristics of the fins composed only of the base material in this embodiment (see FIG. 5(b)). ), the upper side of the fin is less likely to bend, and the tip portion of the fin called the tip is more likely to bend. More specifically, the fins of the present embodiment can easily accelerate the surfboard 2 because the upper side of the fins is less likely to bend due to fluid resistance when the direction of travel of the surfboard 2 is changed. Also, even when the speed of the surfboard 2 is high, only the tips of the fins are likely to bend due to the fluid resistance when the surfboard 2 changes its direction of travel. Due to the restoring force based on this, the tip part of the fin can easily return from a bent state to a straight state, and the fin can easily release the water. .

In addition, since the strength of the fin on the surfboard 2 side (upper side) is easily ensured by the core material 11, the thickness of the fin can be suppressed.

In addition, since the core material 11 is arranged along the outer shape of the fin, it is possible to create a strength distribution that does not hinder the original function of the fin.

In addition, since the core material 11 extends to the inside of the

leg parts

12, 12 of the fins attached to the back surface 2a of the surfboard 2, the

leg parts

12, 12 can be reinforced by the core material 11.

In addition, since the rear end 11a of the core member 11 is located forward of the base point P1 of the rear edge portion 10a of the fin, the rear end side of the fin can be easily bent, and the steerability of the surfboard 2 is improved. . In addition, since the tip 11b of the core member 11 is located above the vertex P2 of the rear edge portion 10a of the fin, the tip side of the fin tends to bend and the steerability of the surfboard 2 is improved.

In addition, since the core material 11 is a wire material, the fin can be lightened while exhibiting high strength.

In addition, since the core material 11 is adhered by welding the base material 10 to the outer surface thereof, the strength of the base material 10 and the core material 11 constituting the fin can be enhanced. Further, since the core material 11 is less likely to come into direct contact with water, corrosion of the core material 11 can be prevented. In addition, since no gap is formed between the core material 11 and the base material 10, it is possible to suppress the ingress of water into the fins or an increase in the weight of the fins due to the absorption of water by the base material 10 and the core material 11.

In addition, since the base material 10 is translucent due to the fact that the main material is polycarbonate, the core material 11 arranged inside the base material 10 can be confirmed from the outside. Abnormalities can be detected early. Further, by making the core material 11 arranged inside the base material 10 visible from the outside, the design can be enhanced. Thus, the substrate preferably has translucency.

Also, since the fins of the first embodiment are manufactured by insert molding, the manufacturing process can be simplified.

It goes without saying that the bending characteristics of the fins in Example 1 can be adjusted by changing the bent shape of the wire material that constitutes the core material. In addition, in order to exhibit the bending characteristics of the fin that can achieve both the straightness and steering performance of the surfboard 2 as described above, the rear end of the core material must be located forward of the base point P1 of the rear edge portion 10a of the fin, and It is preferable that the tip (lower end) of the core material is bent so as to be positioned above the vertex P2 of the rear edge portion 10a of the fin. In other words, since the core material is not arranged on the rear side of the phantom line α and on the lower side of the phantom line β, the fin increases the elasticity of the core material on the base end side of the fin and increases the elasticity of the fin on the tip side of the fin. In , it is possible to secure the original easiness of bending of the base material 10, that is, it becomes easy to exhibit the bending characteristics of the fin that can achieve both the straightness of the surfboard 2 and the steering performance.

In addition, the base material is not limited to being composed of a single layer, and may be composed of, for example, a plurality of laminated layers of different materials.

In addition, both upper ends of the core material do not have to extend into the inside of the

legs

12 , 12 . In this case, it is preferable that the upper end portion of the core member extends to the vicinity of the base 10b from the viewpoint of exhibiting the bending characteristics of the fins that can achieve both the strength of the fins and the straightness and steering performance.

Also, the core material may be composed of a plurality of wire rods divided in the extending direction thereof, or may be composed of a plurality of wire rods arranged side by side in the width direction.

Next, a fin according to Example 2 will be described with reference to FIGS. 6 and 7. FIG. In the second embodiment, the side fins 1L formed on the flat foil will be described as an example, and the description of the configuration that is the same as that of the above-described embodiment will be omitted.

As shown in FIG. 6, the side fins 1L of the second embodiment (hereinafter sometimes referred to as fins) are composed of a base material 10 forming the outer shape of the fin, a surfboard 2 side inside the base material 10, That is, it is composed of

core members

211A and 211B that are arranged biased toward the upper side.

In the second embodiment, the

core members

211A and 211B are two wire rods made of stainless steel and having a circular cross section (see FIG. 7). The

core members

211A and 211B are wire rods having the same diameter, and the core member 211A arranged on the front side is longer than the core member 211B arranged on the rear side.

Note that the

core members

211A and 211B may be composed of wire rods that differ not only in length but also in thickness, material, and the like. For example, as described above, by adopting a flat plate-shaped cross-sectional leaf spring material that is short in the thickness direction of the fin as the core material, the elastic restoring force of the fin is improved and the bending characteristics of the fin are improved. can be greatly increased.

In addition, the

core members

211A and 211B are arranged inside the base material 10 along the outer shape of the fins. Specifically, the core material 211A is curved along the shape of the fin on the front side, and the core material 211B is curved along the shape of the fin on the rear side.

Further, of the

core members

211A and 211B, the rear end 211Ba of the core member 211B extending to the rear side is located forward of the base point P1 of the rear edge portion 10a of the fin. That is, the

core members

211A and 211B extend to a position on the front side of the imaginary line α passing through the base point P1 and extending orthogonally to the base 10b of the fin. Note that the rear end 211Ba of the core material 211B is a portion located at the rear end in the entire core material 211B.

Further, of the

core members

211A and 211B, the tip 211Ab (lower end) of the core member 211A extending to the tip side (lower side) is located above the vertex P2 of the rear edge portion 10a of the fin. That is, the

core members

211A and 211B extend to a position above the imaginary line β passing through the vertex P2 and extending parallel to the base 10b of the fin. Note that the tip 211Ab of the core material 211A is a portion located at the forefront (lowest end) in the entire core material 211A.

In addition, the

core members

211A and 211B extend downward so as to gradually approach each other. The

core members

211A and 211B are not limited to having the same diameter over the entire length. For example, the leading end 211Ab of the core member 211A or the rear end 211Ba of the core member 211B may be formed with a large diameter. or may be tapered.

In addition, the upper ends 211Ac and 211Bc of the

core members

211A and 211B extend into the two front and

rear legs

12 and 12, respectively. Ends 211Ac and 211Bc of the

core members

211A and 211B are exposed to the upper surface 12a of the leg 12 at their end surfaces. The exposed portions of the

core materials

211A and 211B may be covered with the material of the base material 10, caulking material, or the like.

Further, as shown in FIG. 7, the

core members

211A and 211B are arranged substantially in the center of the fin in the thickness direction (horizontal direction). Further, the outer surfaces of the

core members

211A and 211B are adhered to the base material 10 with an adhesive 210. As shown in FIG. That is, the

core members

211A and 211B are integrally formed with the substrate 10 with the adhesive 210 interposed therebetween. In FIG. 7, for convenience of explanation, only the adhesion state of the core material 211A to the base material 10 by the adhesive 210 is illustrated in an enlarged part, but the core material 211B to the base material 10 by the adhesive 210 is shown in an enlarged portion. is the same as that of the core material 211A.

A method for manufacturing the side fins 1L will now be described. In the second embodiment, the side fins 1L are formed by first pouring the material of the base material 10 heated and melted into a mold corresponding to the shape of the fin, cooling and solidifying it, and then forming the

legs

12, 12 of the base material 10. It is manufactured by inserting the

core members

211A and 211B from the upper surface 12a of each. Specifically, the mold is configured so that insertion holes 10c for inserting the

core members

211A and 211B are formed in advance in the upper surfaces 12a of the

legs

12 and 12 when the base material 10 is solidified in the mold, The

core members

211A and 211B are inserted in a state in which an appropriate amount of the adhesive 210 is filled in the insertion hole 10c. As a result, the outer surfaces of the

core members

211A and 211B are adhered to the substrate 10 with the adhesive 210 over the entire length in the insertion hole 10c.

It should be noted that the fins of the second embodiment may be manufactured by insert molding in the same manner as the fins of the first embodiment. In this case, the substrate 10 is welded to the outer surfaces of the

core members

211A and 211B.

According to this, by dividing the

core materials

211A and 211B into two wires, it becomes easier to lower the strength of the tip side of the

core materials

211A and 211B as compared with the wire rod having a bent shape as in the first embodiment. Therefore, the tips of the fins can be easily bent.

Further, of the

core members

211A and 211B, the rear end 211Ba of the core member 211B extending to the rear side is located forward of the base point P1 of the rear edge portion 10a of the fin, so that the rear end side of the fin bends. and the steering performance of the surfboard 2 is improved. In addition, of the

core members

211A and 211B, the tip 211Ab (lower end) of the core member 211A extending to the tip side (lower side) is located above the vertex P2 of the rear edge portion 10a of the fin. It becomes easy to bend near the tip side, and the steerability of the surfboard 2 is improved.

In addition, since the outer surfaces of the

core members

211A and 211B are adhered to the base material 10 with the adhesive 210, the strength of the base member 10 and the

core members

211A and 211B constituting the fins can be enhanced. Further, since the

core members

211A and 211B are less likely to come into direct contact with water, corrosion of the

core members

211A and 211B can be prevented. In addition, since no gap is formed between the

core members

211A and 211B and the insertion holes 10c in the base material 10, the fins lose weight due to the ingress of water into the fins or the absorption of water by the base material 10 and the

core materials

211A and 211B. increase can be suppressed.

In addition, the fins of Example 2 are manufactured by inserting the

core members

211A and 211B into the base material 10 molded by the mold later, so that the manufacturing process can be simplified.

It should be noted that the insertion hole 10c is not limited to being molded by a mold, and may be formed by drilling the molded base material 10 using a drill or the like.

The gap between the

core members

211A and 211B and the insertion hole 10c may not be filled with adhesive, but in this case the gap should be small enough to prevent the

core members

211A and 211B from moving relative to the substrate 10. is preferred.

Further, the fins in the second embodiment can be changed not only by changing the length, thickness, material, etc. of the wire rods forming the

core members

211A and 211B, but also by changing the curvature and arrangement of the

core members

211A and 211B. Needless to say, the characteristics can be adjusted.

Also, the core material may be composed of one wire or three or more wire rods.

Next, a fin according to Example 3 will be described with reference to FIG. It should be noted that the description of the configuration that is the same as that of the above-described embodiment and overlaps will be omitted.

As shown in FIG. 8, the fin of Example 3 includes a base material 10 forming the outer shape of the fin, a core material 311 disposed inside the base material 10 so as to be biased toward the surfboard 2 side, i.e., the upper side, consists of

In the third embodiment, the core material 311 is a plate material made of stainless steel. Note that the core material 311 is a flat plate material having a substantially uniform overall thickness.

In addition, the plate material used as the core material is not limited to having a substantially uniform thickness as a whole, and may be thin and easily bendable, for example, by pressing the front end side (lower end side). Further, the plate material used as the core material may be provided with grooves, through-holes, or the like so that the tip side thereof can be easily bent.

In addition, the core material 311 is arranged inside the base material 10 along the outer shape of the fins. Specifically, the core member 311 has an outer shape similar to that of the fin, and the rear end 311a is located on the rear side of the base point P1 of the rear edge portion 10a of the fin. That is, the core member 311 extends to a position on the rear side of the imaginary line α passing through the base point P1 and extending orthogonally to the base 10b of the fin. By doing so, the high rigidity of the core material 311 can be exhibited to the rear end side of the fin. Note that the rear end 311a of the core material 311 is a portion located at the rearmost end in the entire core material 311 .

In addition, the tip 311b (lower end) of the core material 311 is located above the vertex P2 of the rear edge portion 10a of the fin. That is, the core material 311 extends to a position above the imaginary line β passing through the vertex P2 and extending parallel to the base 10b of the fin. Note that the tip 311b of the core material 311 is a portion located at the most extreme end (lowest end) in the entire core material 311 .

According to this, since the core material 311 is made of a plate material, strength can be ensured even if the core material 311 is thin, and the thickness of the entire fin can be reduced.

In addition, since the core material 311 can have an outer shape close to the outer shape of the fin, it is possible to create a strength distribution that does not hinder the original function of the fin.

It should be noted that the fins of Example 3 can be produced by either a manufacturing method by insert molding as in Example 1 or a manufacturing method in which a core material is inserted after molding of the base material 10 as in Example 2. can also be manufactured.

Also, the core material 311 may have a convex portion extending inside the

leg portions

12 , 12 .

Further, the core material 311 may be divided into a plurality of parts, and for example, the plate material forming the core material may be divided into a front side and a rear side.

Next, a fin according to Example 4 will be described with reference to FIG. It should be noted that the description of the configuration that is the same as that of the above-described embodiment and overlaps will be omitted.

As shown in FIG. 9, the fin of the fourth embodiment includes a base material 10 that forms the outer shape of the fin, and

core members

411A and 411B that are biased toward the surfboard 2 side, that is, the upper side of the base material 10 inside the base material 10. and consists of

In the fourth embodiment, the core material 411A is a single wire made of stainless steel, and the core material 411B is a plate material made of stainless steel. Further, the core material 411A is bent along a portion of the outer periphery of the core material 411B and arranged so as to be in contact with the core material 411B. Note that the

core members

411A and 411B may be separate or integrated.

In addition, the rear end 411Aa of the core material 411A is located forward of the base point P1 of the rear edge portion 10a of the fin. That is, the core member 411A is bent so as to be positioned forward of the imaginary line α passing through the base point P1 and extending orthogonally to the base 10b of the fin. Note that the rear end 411Aa of the core 411A is the rearmost portion of the entire core 411A.

Further, the tip 411Ab (lower end) of the core material 411A is located above the vertex P2 of the rear edge portion 10a of the fin. That is, the

core members

411A and 411B are bent so as to be positioned above the imaginary line β passing through the vertex P2 and extending parallel to the base 10b of the fin. Note that the tip 411Ab of the core material 411A is a portion located at the forefront (lowest end) in the entire core material 411A.

In addition, the core material 411A has both upper ends 411Ac and 411Ad extending to the interior of the two front and

rear legs

12 and 12 .

According to this, the

core members

411A and 411B can be mutually reinforced by combining the core member 411A made of the wire material and the core member 411B made of the plate material.

Next, a fin according to Example 5 will be described with reference to FIG. It should be noted that the description of the configuration that is the same as that of the above-described embodiment and overlaps will be omitted.

As shown in FIG. 10, the fins of the fifth embodiment are composed of glass fibers on both sides of the core material 511, which is a plate material made of stainless steel, and which is placed in the center of the fin in the thickness direction. It is configured by laminating four glass cloths 513 each and hardening them with a polyester resin. The fins in Example 5 are shaped by removing and polishing unnecessary portions of the base material solidified in the pair of molds.

The core material 511 in this embodiment has two front and rear legs, and is arranged inside the base material so as to be biased toward the surfboard 2 side, ie, the upper side.

It should be noted that members other than the glass cloth 513 may be laminated on both sides of the core material 511 in the base material in the fifth embodiment.

Further, the core material in Example 5 is not limited to a plate material, and may be, for example, a wire material as in Examples 1 and 2, or a combination of a wire material and a plate material as in Example 4. .

Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments, and any changes or additions within the scope of the present invention are included in the present invention. be

For example, in the above embodiments, an example in which a wire or plate is used as the core material has been described, but the core material is not limited to this. It may be processed into a shape.

In addition, the entire leg of the fin may be configured as part of the core material.

1C center fin (fin)
1L, 1R side fins (fins)
2 surfboard (board)
2a back surface 3 fin box 4 bolt 10 base material 10a rear edge portion 10b base 10c insertion hole 11 core material 11a rear end 11b tip 11c, 11d upper end 12 leg 12a upper surface 210 adhesive 211A core 211Ab tip 211Ac end 211B core Material 211Bc End 211Ba Rear end 311 Core material 311a Rear end 311b Tip 411A Core material 411Aa Rear end 411Ab Tip 411B Core material 511 Core material 513 Glass cloth P1 Base point P2 Vertex α, β Virtual line

Claims

A fin attached to the back side of the board,
A fin, wherein a core material having high strength is arranged in the fin so as to be biased toward the board.
The fin according to claim 1, wherein the core material is arranged along the contour of the fin.
The fin according to claim 1 or 2, characterized in that said core member extends to the leg portion of said fin attached to the back side of said board.
The fin according to claim 1 or 2, characterized in that the tip of the core material is located closer to the board than the vertex of the rear edge portion of the fin.
The fin according to claim 1 or 2, characterized in that the rear end of the core material is located forward of the base point of the rear edge portion of the fin.
The fin according to claim 1 or 2, wherein the core material is a wire material.
The fin according to claim 1 or 2, wherein the core material is adhered to the base material.