WO2023193067A1

WO2023193067A1 - Surfboard fin and method for use thereof

Info

Publication number: WO2023193067A1
Application number: PCT/AU2023/050288
Authority: WO
Inventors: Neal Cameron
Original assignee: Neal Cameron
Priority date: 2022-04-09
Filing date: 2023-04-09
Publication date: 2023-10-12

Abstract

A surfboard fin having mounting elements (95) for removably attaching the fin to a fin box of a surfboard may have an angle of attack (110) that is defined by a line from the leading edge (92) to the trailing edge (94) of the fin. The angle of attack (110) may be offset from a mounting axis (112) defined through the mounting elements of the fin. The offset enables a surfboard to be tuned to create directional performance characteristics for the surfboard.

Description

SURFBOARD FIN AND METHOD FOR USE THEREOF

FIELD OF THE INVENTION

[0001] This disclosure relates to a surfboard fin, to a surfboard incorporating at least one surfboard fin, and to a method of use of the surfboard fin.

BACKGROUND OF THE INVENTION

[0002] Surfboards are equipped with fins to provide stability, direction and control while surfing. Surfboard fins may be either fixed within the board, or may be removeable. While fins can be replaced, there is very little opportunity to tune the board for toe angle, due to the generic nature of fins. What is required is an improved fin that enables tuning of the surfboard.

SUMMARY OF THE INVENTION

[0003] In one aspect of the disclosure, there is provided a fin for a surfboard, the fin including: a fin element extending substantially along a fin plane from a forward end to a rearward end, the fin element including: a leading edge at a forward end of the fin element; a trailing edge at a rearward end of the fin element; at least one mounting element extending from the fin element for removably mounting the fin into a complementary engagement element of a surfboard, the at least one mounting element having a mounting axis that aligns with an axis of the complementary engagement element in a plane of the surfboard; wherein an angle of attack is defined by a line that is in a plane that is substantially perpendicular to the fin plane and that substantially corresponds, when the fin is mounted to a surfboard, to the plane of the surfboard; and that passes from the leading edge to the trailing edge; and wherein the angle of attack is at an angle to the mounting axis.

[0004] In one aspect of the disclosure, there is provided a method of configuring the turning characteristics of a surfboard including : selecting at least one fin to be removably mounted to the surfboard in a plane substantially perpendicular to a plane of the surfboard; and mounting the at least one fin to the surfboard; wherein the at least one fin includes: a fin element extending substantially along a fin plane from a forward end to a rearward end, the fin element including : a leading edge at a forward end of the fin element; a trailing edge at a rearward end of the fin element ; at least one mounting element extending from the fin element for removably mounting the fin into a complementary engagement element of a surfboard, the at least one mounting element having a mounting axis that aligns with an axis of the complementary engagement element in a plane of the surfboard; wherein an angle of attack is defined by a line that is in a plane that is substantially perpendicular to the fin plane and that substantially corresponds, when the fin is mounted to a surfboard, to the plane of the surfboard; and that passes from the leading edge to the trailing edge; and wherein the angle of attack is at an angle to the mounting axis.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Reference will now be made, by way of example only, to specific embodiments and to the accompanying drawings in which:

[0006] Fig. 1 schematically shows a top view of a center fin profile in accordance with the prior art, (as viewed from the bottom of the surfboard) ;

[0007] Fig. 2 schematically shows a top view of a left fin profile in accordance with the prior art;

[0008] Fig. 3 schematically shows a top view of a right fin profile in accordance with the prior art;

[0009] Fig. 4 schematically shows a neutral fin mounting arrangement for prior art fins;

[0010] Fig. 5 schematically shows a toed-in fin mounting arrangement for prior art fins;

[0011] Fig. 6 schematically shows a more toed-out fin mounting arrangement for prior art fins;

[0012] Fig. 7 shows a side profile of a prior art fin;

[0013] Fig. 8 shows a top view of the fin of Fig. 7;

[0014] Fig 9 schematically depicts a top view of a fin in accordance with an embodiment of the present disclosure;

[0015] Fig. 10 depicts the profile of the fin of Fig. 9 overlaid on the profile of the fin of Fig. 8;

[0016] Fig. 11 depicts an angle of attack of the fin of Fig. 9 relative to a mounting axis;

[0017] Fig. 12 schematically depicts a top view of a fin in accordance with an alternative embodiment of the present disclosure ; [0018] Fig. 13 schematically depicts an installation of toedin fins on a surfboard with fin boxes set in a neutral mounting position;

[0019] Fig. 14 schematically depicts an installation of toed- out fins on a surfboard with fin boxes set in a neutral mounting position;

[0020] Fig. 15 schematically depicts an installation of asymmetric fins on a surfboard with fin boxes set in a neutral mounting position;

[0021] Fig. 16 depicts a block of fin material for shaping a fin; and

[0022] Fig. 17 depicts a shaping step for forming the fin foil cross-sectional profile.

DETAILED DESCRIPTION OF THE INVENTION

[0023] Surfboard fins are used to assist with stability, direction and control when maneuvering a surfboard through the water. Fins are generally planar elements with a hydrodynamic profile extending along a fin plane from a forward or leading edge (as determined by the intended usage direction on a surfboard) to a rearward or trailing edge. If the surfboard is considered to lie in a horizontal plane, the fin plane will typically lie in a vertical plane substantially parallel (though not necessarily exactly parallel) with a longitudinal axis of the surfboard. It is common for a surfboard to adopt a three fin design, with one central fin mounted along the longitudinal axis or centerline of the surfboard, and two (or more) lateral fins to the left and right of the centerline. The fins may also be considered to have a longitudinal axis with a front edge, also referred to as a toe, head or leading edge, and a rear edge, also referred to as a heel, tail or trailing edge. [0024] A center fin typically has a symmetrical teardrop profile about its centerline from the leading edge to the trailing edge, with the leading edge and trailing edge both disposed on the centerline. An example of a center fin profile 10, as viewed from above or below the fin, is shown in Fig. 1. The fin 10 has a leading edge 12, a trailing edge 14 and left 16 and right 18 teardrop profile faces.

[0025] Side fins are typically asymmetrical with the outer face of the fin, i.e. toward the surfboard rail, being teardrop shaped, while the inner face, i.e. toward the centerline, is relatively flat or slightly concave. Examples of left and right fin profiles are shown in Figs. 2 and 3 respectively. The left fin 20 has an outer face 26 having a teardrop profile and a relatively flat inner face 28. The right fin (in the example) is the mirror image of the left fin.

[0026] Fig. 4 shows the underside surface of a surfboard 40 and schematically indicates the positions of the fins for a neutral manufacturers setting mounting position. For the purpose of the following description, terms of orientation, such as left and right will be considered with reference to a view from the top of the surfboard. Thus, the underside views such as Fig. 4 will show the "left" side fin on the right side of the view, and consequently, the "right" side fin will be shown on the left side of the view. Furthermore, reference to particular axes throughout this description and any claims that follow, such as a mounting axis, longitudinal axis, fin axis or angle of attack axis, shall be a reference to that axis as viewed in the plane of the surfboard to which the fin would be mounted.

[0027] Any center fins 42 will, naturally, be mounted on the centerline 420 of the surfboard. In the neutral mounting position, the side fins 43, 44 are mounted with an angle that points the longitudinal axis of the respective side fin toward the nose 46 of the surfboard. That is, the side fins are not necessarily exactly aligned or parallel with the longitudinal axis of the surfboard. An alternative to the neutral mounting position is shown in Fig. 5. In this position, termed a toed-in position, the side fins are angled to the longitudinal axis more than for the neutral position so that the longitudinal axes of the respective side fins cross at a point aft 50 of the nose of the surfboard. Fig. 6 shows the opposite of the toed-in position, termed a toed-out position, in which the longitudinal axes of the respective side fins cross at a point 60 forward of the nose of the surfboard.

[0028] Each fin mounting position provides the surfboard with different wave handling characteristics.

[0029] Fins may be fixed, i.e. set into the surfboard, or removeable. Removable fins have the advantage of easier transport and less risk of damage during transport, as well as allowing a degree of variable fin selection for different surf conditions. Fixed fins will typically be mounted in the neutral mounting position (Fig. 4) or a slightly toed-in position (approximately 3- 7 degrees which may be referred to as the manufacturer's preferred position) (Fig. 5) but can be tailor made to other configurations.

[0030] Removeable fins are mounted via a fin box or other system which is set in a base of the surfboard and provides a complementary locking engagement for the removeable fin. The axis angle of the fin box or, more generally, the complementary engagement system within the surfboard, sets the angle of the fin. That is, the fin box may be set within the surfboard to provide a neutral position, a toed-in position or toed-out position for the fins. As for fixed fins, fin boxes are typically set within a surfboard by the manufacturer to provide either a neutral configuration or a slightly toed-in configuration. [0031] Typically, the amount of toe-out never exceeds the parallel line represented by the stringer or centreline of the board .

[0032] An example of a prior art removable fin 70 is depicted in Fig. 7. The fin includes a fin element 72 and a set of mounting elements 74. The fin element 72 is planar, extending along a fin plane. The fin element 72 includes a leading edge 720 extending from a nose 722 past a tip 723 of the fin to the tail 724 and a trailing edge 726 that extends from the back 728 of the mounting section to the tail 724. The mounting elements 74 are received into the fin box so that the fin element 72 projects from the surfboard above the line 76. Various engagement mechanisms are known in the art and the specific engagement mechanism for the fin is not considered pertinent for the purposes of the present disclosure .

[0033] The particular shape of the fin depicted in Fig.7 is indicative only. Fins may be produced in a range of shapes.

[0034] Fig. 8 schematically shows the fin 70 from the direction of the mounting elements 74. The mounting elements 74 have a mounting chord or axis 82. The mounting chord 82 is the angle at which the fin is mounted within the fin box and sets the angle of the fin to the surfboard, i.e. establishes the fin as being neutral, toed-in or toed-out. An angle of attack of the fin may be defined by a line 84, in the horizontal plane corresponding to the plane of the surfboard (i.e. perpendicular to the vertical fin plane) passing from the tip 722 to the tail 724. As is shown in Fig. 8, for prior art fins, the mounting chord 82 is parallel with the angle of attack.

[0035] Whether the fins are removable or fixed, the mounting position of the fins is set when the board is manufactured. Therefore, whether the fins are toe-in, toe-out or neutral, is set once the board is manufactured (and, if relevant, a fin-box or comparable mounting system is installed) . This means that the surfboard cannot be readily tuned to different conditions that may be affected by toe angles.

[0036] The present inventor has found that a modified fin design can allow a range of tuning options to be made. A side fin in accordance with an embodiment of the present disclosure is depicted in Fig. 9. The fin 90 is a plane element extending along a fin plane and includes a toe end 92, tail 94, outer or rail face 96 and inner face 98. The fin also includes mounting elements 95. The fin may appear similar in side view to the side view of prior art fin 70 of Fig. 7. The particular side view shape of the fin is not considered pertinent to the present disclosure and a range of shapes will be apparent to the person skilled in the art. Unlike a prior art side fin, such as shown in Fig. 2, the inner face 98 of the fin 90 is not straight. Instead, a rear section 910 of the inner face 98 is curved outward, toward the rail face 96, moving in the direction toward the tail 94.

[0037] The effect of the curved tail profile is to displace the tail edge 94 away from the plane 102 that is tangential to the innermost portion of the inner face 98. The tail displacement 912 may be represented as a distance x mm. In one embodiment, the tail displacement, x, may be in the range of l-7mm, and in one specific embodiment, the displacement, x, may be in the range of 3-4mm.

[0038] The portion 910 of the rear section that includes the modified profile may be considered as a percentage y% of the length of the fin. In one embodiment, y may be at least 5% of the rearmost portion of the fin. In one embodiment, y may be at least 20% of the rearmost portion of the fin. In one embodiment, y may be at least 50% of the rearmost portion of the fin. In one embodiment, y may be at least 66% of the rearmost portion of the fin. In an alternative embodiment, the inner surface may be continuously curving from the tip to the tail. [0039] Optionally, the toe end of the fin 920 may also include a curved profile that displaces the toe end 92 away from the tangential plane 102 by a small amount z mm. The displacement z may be less than the displacement x.

[0040] Fig. 10 shows a fin having a modified profile as herein described (solid line) overlaid on a prior art fin (broken line) to show the differences in the fin shape.

[0041] Fig. 11 shows how the angle of attack, indicated by the solid line 110 between the tip 92 and tail 94 is now angled relative to the longitudinal axis (mounting axis) set by the mounting chord 112 (dashed line) passing through the mounting elements 95. In various embodiments, the angle of attack may be from 0.25 to approximately 10 degrees from the mounting axis set by the mounting chord. In the example shown, the angle of attack is at approximately 2 degrees to the fin mounting axis 112.

[0042] The offset between the angle of attack and the mounting axis will be most pronounced, i.e. a maximum, at the top edge of the fin element, i.e the edge from which the mounting elements extend. Moving down the fin toward the fin tip, the angle of attack will appear to straighten with respect to the mounting axis due to the foiling shape of the fin.

[0043] The fin 90 may be considered as a left side toe-in fin. As viewed from above, if the fin 90 were to be underneath a surfboard, the face 96 would be the rail-side face and the face 98 would be the centerline face. A right side toe-in fin would be the mirror image of fin 90.

[0044] Fig. 12 shows an alternative embodiment 120 of a side fin having a more exaggerated curved profile in the tail portion, and no profile in the toe portion. In this example, the angle of attack 122 is approximately 4 degrees to the mounting axis 124.

[0045] Fins having a modified profile as described herein have an angle of attack, as defined by the line extending from the tip to the tail along a horinzontal plane or section of the fin, that is at an angle to the mounting axis of the fin, as set by a line passing along the axis of the mounting portions, which will correspond to the axis of the fin box within the surfboard. Because the angle of attack of the fin will be at an angle to the axis of the fin box, different selections of fins can allow for the amount of toe-in or toe-out angle to be adjusted, allowing the performance of the surfboard to be tuned after manufacture of the board and setting of the fin mountings .

[0046] Fig. 13 shows a surfboard 130 with side fin mounting systems 132, 134 schematically depicted in a neutral mounting position indicated by mounting axes 136, 138. Standard fins, i.e. in accordance with the prior art, will be fixed in a neutral position, i.e. neither toe-in nor toe-out. However, this setting can be altered by the use of fins as described. For example, selection of a left and right toe-in fin of the type depicted in Fig. 9, having an angle of attack of 2 degrees inward (as indicated by axes 137, 139) to the respective fin box mounting axis, will change the performance of the surfboard to having a more toed-in characteristic .

[0047] To produce a toed-out characteristic as depicted in Fig. 14, the left and right fins can be swapped. That is, a left side toe-in fin may be considered as a right-side toe-out fin. Mounting the left side toe-in fin on the right side, and vice versa, will produce a toe-out characteristic in which the angle of attack axis 147, 149 converge forward of the nose of the surfboard.

[0048] It is not imperative that the fins are chosen and installed symmetrically, i.e. with angles of attack having equal magnitude but opposite direction. An asymmetric fin selection can be used to account for imperfections and imbalances in the board manufacture, or to give a surfboard directional handling characteristics which may enhance performance in certain types of surf conditions. For example, some surf breaks, wavepools, etc. may be considered to be directional, requiring predominantly gentle turns in one direction but tight turns in the other.

[0049] Directional characteristics may be created by an asymmetric fin selection, i.e fins having either different magnitude angles of attack, non-opposite angles of attack, or both. For example, two left fins may be selected so that the left fin is a toed-in fin while the right fin is toed-out. Alternatively, a left and right fin may be selected having different angle of attack characteristics, e.g. 2 degrees and 5 degrees, respectively, giving the right side a more toed-in characteristic in this example. It can thus be seen that a range of toe tuning options are available by selecting one or more fins with the required inbuilt toe angle.

[0050] Fig. 15 shows an example of an asymmetric fin selection. The surfboard 150 may be fitted with one toed-in fin 152 having an angle of attack axis 153 and one toed-out fin 154 having an angle of attack axis 155. The angles of attack converge at a point 156 which is displaced laterally of the centerline 158 which will create a direction based performance in the surfboard.

[0051] The modified fin profile has, heretofore, been described as being for a side fin. In other embodiments, the fin can be used as a center fin. For example, a single fin board can have a non-symmetrical fin, to create a directional characteristic in the single fin board.

[0052] Selections of fins having a modified fin profile can be used to create a range of handling characteristics. While example parameters of the fin profile are provided herein, the person skilled in the art will readily understand that modifications of these parameters may be made while still achieving the benefits of a fin in which the angle of attack is at an angle to the mounting axis of the fin box. [0053] The surfboard fins may be produced from f iberglass/resin composites, plastic, or any suitable material. In one embodiment, a rectangular block of material 200 as shown in Fig. 16 may be the starting point. Profiles sections 202, 204, 206, 208 may be removed along the height of the block 200 to produce a fin block 210 having the required horizontal cross section (Fig. 17) . The profile sections may be removed by grinding, cutting or similar processes. The profiled fin block 210 may then be cut into a fin outline, e.g. as shown in Fig. 7.

[0054] The amount of material that is removed for each profile section 202, 204, 206, 208 will depend on the desired angle of attack for the fin. For example, for a greater angle of attack than shown in Fig. 17, the section 204 may not be removed at all to leave the side edge straight and the section 206 that is removed may be wider at the tail.

[0055] The illustrations of the fin are for the purposes of describing the present embodiments only and should not be considered as drawn to scale. Exaggerations may be made in the figures to illustrate the principles and concepts of the embodiments that are being described.

[0056] Fins may be manufactured by any suitable method known in the art, e.g. by hand, moulded, CNC machined or 3-D printed. Although embodiments of the present invention have been illustrated in the accompanied drawings and described in the foregoing description, it will be understood that the invention is not limited to the embodiments disclosed, but is capable of numerous rearrangements, modifications, and substitutions without departing from the spirit of the invention as set forth and defined by any claims based on the subject matter disclosed.

Claims

CLAIMS WHAT IS CLAIMED IS:

1. A fin for a surfboard including: a. a fin element extending substantially along a fin plane from a forward end to a rearward end, the fin element including: i. a leading edge at a forward end of the fin element ; ii. a trailing edge at a rearward end of the fin element ; b. at least one mounting element extending from the fin element for removably mounting the fin into a complementary engagement element of a surfboard, the at least one mounting element having a mounting axis that aligns with an axis of the complementary engagement element in a plane of the surfboard; c. wherein an angle of attack is defined by a line: i. that is in a plane that is substantially perpendicular to the fin plane and that substantially corresponds, when the fin is mounted to a surfboard, to the plane of the surfboard; and ii. that passes from the leading edge to the trailing edge d. wherein the angle of attack is at an angle to the mounting axis.

2. The fin of claim 1 wherein the fin element comprises an outward face and an inward face, wherein the outward face is defined as the face of the fin element that the angle of attack is angled towards in the direction from the leading edge to the trailing edge. The fin of claim 2 wherein the inward face is convex. The fin of claim 2 wherein a curved portion of the inner face curves toward the outward face in the direction from the leading edge to the trailing edge. The fin of claim 4 wherein the curved portion is at least 25% of a length of the fin from the trailing edge. The fin of any one of claims 1 to 5 wherein the angle of attack is at least 0.25 degrees relative to the mounting axis . The fin of any one of claims 1 to 5 wherein the angle of attack is at least 1 degree relative to the mounting axis . The fin of any one of claims 1 to 5 wherein the angle of attack is at least 1.5 degrees relative to the mounting axis . The fin of any preceding claim wherein an offset between the angle of attack and the mounting axis is a maximum at an edge of the fin element where the at least one mounting element extends from the fin. A method of configuring the turning characteristics of a surfboard including: a. selecting at least one fin to be removably mounted to the surfboard in a plane substantially perpendicular to a plane of the surfboard, the at least one fin including : i. a fin element extending substantially along a fin plane from a forward end to a rearward end, the fin element including:

1. a leading edge at a forward end of the fin element ;

2. a trailing edge at a rearward end of the fin element; ii. at least one mounting element extending from the fin element for removably mounting the fin into a complementary engagement element of the surfboard, the at least one mounting element having a mounting axis that aligns with an axis of the complementary engagement element in a plane of the surfboard; iii. wherein an angle of attack is defined by a line:

1. that is in a plane that is substantially perpendicular to the fin plane and that substantially corresponds, when the fin is mounted to the surfboard, to the plane of the surfboard; and

2. that passes from the leading edge to the trailing edge; iv. wherein the angle of attack is at an angle to the mounting axis; b. mounting the at least one fin to the surfboard.

The method of claim 10 including mounting the at least one fin on a centerline of the surfboard. The method of claim 10 or 11 including mounting the at least one fin to a side of the centerline of the surfboard . The method of claim 12 wherein selecting the at least one fin includes selecting at least two fins and mounting the at least two fins to opposite sides of the centerline of the surfboard. The method of claim 13 wherein the at least two fins include angles of attack that have equal magnitude but opposite direction. The method of claim 13 wherein the at least two fins include angles of attack of different magnitude. The method of claim 13 wherein the angles of attack of the at least two fins converge at a point that is displaced laterally of the centerline of the surfboard.