Surfboard Fins

Abstract

To provide a fin for a surfboard which can easily balance the lateral swing of the surfboard. [Solution] The fin 50 is attached to the lower part of the rear part 10R of the surfboard body 10, and is characterized by an inverted Y shape when viewed from behind, having a hanging plate 51 hanging downward from the rear part 10R of the surfboard body 10 and an inclined plate 52 extending diagonally downward to the left and right from the lower part of this hanging plate 51.

Description

[Technical field]

[0001] The present invention relates to surfboard fins, and more particularly to surfboard fins that can easily balance the side-to-side swing of a surfboard. [Background technology]

[0002] Conventionally, a technique such as that shown in Patent Document 1, for example, has been known.

[0003] <Patent Document 1> JP 2005-280376 A Patent Document 1 states: The objective of this project is to "install this device on the rear underside of a surfboard to stabilize and improve its maneuverability in terms of straight-line travel, rotation and acceleration." "Two mounting pieces 1, 1 for attaching to the underside of a surfboard, a fin base 2 extending from the two mounting pieces 1, 1, a diagonally downward fin section 3 extending from the rear end of the fin base 2, and a diagonally upward fin section 4 extending from the rear end of the fin base 2 are integrally constructed from carbon fiber. The diagonally downward fin section 3 and the diagonally upward fin section 4 are gradually made thinner toward the rear end to give them elasticity." Fins for surfboards are described (ibid. abstract).

[0004] However, Patent Document 1 does not describe any technical matters that focus on making it easier to balance the surfboard against lateral swaying.

[0005] <Patent Document 2> U.S. Patent Application Publication No. 2007 / 0093154 Paragraph "0092" and Figures 13-14 of this patent describe a fin having planar winglets 33 that extend forward from the trailing edge 34 to the maximum width of the foil portion at the tip of the fin.

[0006] However, the planar winglet 33 in Patent Document 2 is provided near the tip of the fin in order to reduce the generation of tip vortices and the associated induced drag, and therefore cannot be said to be designed to make it easier to balance the side-to-side swaying of the surfboard (Summary of the same document, etc.).

[0007] <Patent Document 3> U.S. Patent Application Publication No. 2017 / 0283016 Paragraph "0072" and FIG. 11 of US Pat. No. 5,999,233 describe a fin 10 consisting of a double wing 18 having two downwardly inclined wings 80 that form a "V" in front view.

[0008] However, the wing 80 in Patent Document 3 is not provided directly under the main body 12, but is provided at a position shifted rearward via the arm 14, so it cannot be said that it is intended to facilitate balancing against side-to-side swinging of the surfboard. This is because a twist occurs in the arm 14 due to a moment around the forward direction generated in the wing 80 by the side-to-side swinging of the surfboard. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2005-280376 A [Patent Document 2] US Patent Application Publication No. 2007 / 0093154 [Patent Document 3] US Patent Application Publication No. 2017 / 0283016 Summary of the Invention [Problem to be solved by the invention]

[0010] The problem that the present invention aims to solve is to provide a surfboard fin that can easily balance the side-to-side swing of the surfboard. [Means for solving the problem]

[0011] In order to solve the above problems, the surfboard fin of the present invention is: A fin attached to the bottom of the rear of a surfboard body, When viewed from behind, it has an inverted Y shape, with a hanging board (51) hanging downward from the rear of the surfboard body and inclined boards (52, 52) extending diagonally downward to the left and right from directly below the hanging board (51).

[0012] As a result of the above-mentioned configuration, the following advantages can be obtained with this surfboard fin. When a surfboard provided with this surfboard fin sways left and right in the traveling direction, resistance to the swinging is effectively obtained by the hanging board (51) and the left and right inclined boards (52, 52), so that the surfboard can be easily balanced against the left and right swinging.

[0013] In this surfboard fin, The included angle (θ2) of the inclined plates (52, 52) in rear view is desirably set to be equal to or greater than 90 degrees and equal to or less than 120 degrees. With this configuration, resistance against the left and right swaying of the surfboard can be efficiently obtained by the left and right inclined plates (52, 52), making it easier to maintain good balance against the left and right swaying of the surfboard.

[0014] By increasing the hanging length (H3) of a surfboard fin, the anti-rotational moment (Nm, kgfm) against the side-to-side swaying of the surfboard can be increased, making it easier to achieve good side-to-side balance of the surfboard. However, when considering the strength of the board fin itself, it is possible to increase the anti-rotational moment by increasing the side-to-side length (W5) rather than increasing the hanging length (H3), and the strength of the board fin can also be improved by increasing the side-to-side length (W5) of the bifurcated structure, resulting in a more stable board fin. Therefore, in this surfboard fin, It is desirable that the left-right length (W5) of the inclined plates (52, 52) be longer than the hanging-direction length (H3) of the hanging plate (51). With this configuration, resistance against the left and right swaying of the surfboard can be efficiently obtained by the left and right inclined plates (52, 52), making it easier to maintain good balance against the left and right swaying of the surfboard. [Brief description of the drawings]

[0015] [Figure 1] 1A is a plan view of an embodiment of a surfboard according to the present invention, FIG. 1B is a front view of FIG. 1A as seen from the rear of the board, and FIG. 1C is a right side view of FIG. 1A. [Diagram 2] 1A and 1B are a plan view and a front view for explaining the dimensions of each part of the embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of a surfboard fin according to the present invention will be described with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals.

[0017] A surfboard 1 shown in FIG. 1 is equipped with a surfboard fin (hereinafter simply referred to as a fin) 50 according to an embodiment of the present invention. This Fin 50 is A fin provided on the lower part of the rear part 10R of the surfboard body 10, When viewed from behind (FIG. 1(b)), it has an inverted Y shape with a hanging board 51 hanging downward from rear part 10R of surfboard body 10 and inclined boards 52, 52 extending diagonally downward to the left and right from directly below hanging board 51.

[0018] As a result of the above-mentioned configuration, the surfboard fin 50 provides the following advantages. When a surfboard 1 equipped with this surfboard fin 50 sways left and right in the direction of travel (in the directions of arrows R1 and R2 in FIG. 1(b)), resistance to the swaying is effectively provided by the hanging board 51 and the left and right inclined boards 52, 52, making it easier to balance the left and right swaying of the surfboard 1.

[0019] To explain in more detail, for example, if a surfer stands on surfboard 1 with his left foot 40L and right foot 40R placed on it, and a load F1 due to the surfer's weight acts on the left side of surfboard 1 on the sea surface S, causing surfboard 1 to swing downward to the left as shown by arrow R1, as shown in Figure 1(d), the inclined plates 52, 52 extending downward to the left and right of the inverted Y-shaped fin 50 will push away the seawater, and the reaction forces F2, F3 will create an anti-rotational moment, making it easier to balance the swing of surfboard 1 to the downward left (in the R1 direction).

[0020] Also, for example, as shown in Figure 1(e), if a load F1' due to the surfer's weight acts on the right side of the surfboard 1, causing the surfboard 1 to swing downward and to the right as indicated by arrow R2, a counter rotational moment will act due to the resistance forces F2', F3' caused by the reaction to the inclined plates 52, 52 extending downward to the left and right of the inverted Y-shaped fin 50 pushing aside the seawater, making it easier to balance the swing of the surfboard 1 to the downward and to the right (in the R2 direction).

[0021] To explain further, the reaction forces F3 and F3' shown in Figure 1(d)(e) are not only the reaction forces caused by the inclined plate 52 of the Y-shaped board fin "pushing aside (shear force)" the seawater, but also the "reaction forces against lifting the seawater", and because of the Y-shape, the weight of the seawater pushed up itself has a large effect as a reaction force. Utilizing this effect is the greatest feature of the Y-shaped board fin.

[0022] As described above, the surfboard 1 provided with this surfboard fin 50 makes it easier to maintain balance against lateral swinging. Furthermore, the inverted Y shape improves the strength of the fin 50 itself.

[0023] As shown in FIG. 2(b), the included angle θ2 of the inclined plates 52, 52 in rear view is preferably set to be equal to or greater than 90 degrees and equal to or less than 120 degrees. With this configuration, resistance against lateral swinging of the surfboard 1 can be efficiently obtained by the left and right inclined plates 52, 52, making it easier to maintain a good balance against lateral swinging of the surfboard 1.

[0024] By increasing the hanging length H3 of a surfboard fin, the anti-rotational moment (Nm, kgfm) against the side-to-side swaying of the surfboard can be increased, making it easier to achieve good side-to-side balance of the surfboard. However, when considering the strength of the board fin itself, it is better to increase the side-to-side length W5 rather than increasing the hanging length H3, in order to increase the anti-rotational moment, and the strength of the board fin can also be improved by increasing the side-to-side length W5 of the bifurcated structure, resulting in a more stable board fin. Therefore, in this surfboard fin, it is desirable to configure the left-right length (W5) of the inclined plates (52, 52) to be longer than the hanging direction length (H3) of the hanging plate (51), as shown in Figure 2(b). With this configuration, resistance against the left and right swaying of the surfboard can be efficiently obtained by the left and right inclined plates (52, 52), making it easier to maintain good balance against the left and right swaying of the surfboard.

[0025] The fin 50 can be constructed integrally of a hanging plate 51 and inclined plates 52, 52 using a known suitable material, such as synthetic resin, and can be joined to the board body 10 by a known suitable joining means (e.g., adhesive, welding, bolts and nuts, screws, etc.).

[0026] The surfboard body 10 shown in FIG. 1 may be any suitable known surfboard body.

[0027] Therefore, the dimensions of the various parts of the known surfboard 1 shown in FIG. The description will be given with reference to Figure 2 (see Figure 1 for the reference numerals of each part).

[0028] Overall width W10 = 60cm~80cm (when overall length L10 is about 300cm) ·Total length L10=170cm~300cm Width of footrest W11 = 0~40cm (W11 = 0cm if the waves are calm) Distance between foot rest and left and right sides of board W12 = 10cm~40cm (You may not need to spread your feet apart) - Front-rear length L9 of fin 50 = 30cm to 40cm (if total length L10 is long, it may be 40cm) Fin 50 height H2=15cm~20cm Fin 50 left / right length W5 = 20cm~30cm Height H3 of the hanging plate 51 of the fin 50 = 5cm~10cm The inclination angle (included angle) θ2 of the inclined plates 52, 52 of the fin 50 is preferably 90 degrees to 120 degrees.

[0029] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and can be modified as appropriate within the scope of the gist of the present invention. [Explanation of symbols]

[0030] 1: Surfboard 10: Board body 50: Finn

Claims

1. A fin provided on the lower part of the rear part (10R) of a surfboard body (10), This surfboard fin is characterized by having an inverted Y shape in rear view, which has a hanging board (51) hanging downward from the rear part (10R) of the surfboard body (10) and inclined boards (52, 52) extending diagonally downward to the left and right from directly below the hanging board (51).

2. In claim 1, A surfboard fin characterized in that the included angle (θ2) of the inclined plates (52, 52) when viewed from behind is greater than or equal to 90 degrees and less than or equal to 120 degrees.

3. In claim 1 or 2, A surfboard fin characterized in that the left-right length (W5) of the inclined plates (52, 52) is longer than the hanging direction length (H3) of the hanging plate (51).

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