Surfboard fin and method for use thereof

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.

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.

In one aspect of the disclosure, there is provided a fin for a surfboard, the fin including:

In one aspect of the disclosure, there is provided a method of configuring the turning characteristics of a surfboard including:

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.

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, as viewed from above or below the fin, is shown in. The finhas a leading edge, a trailing edgeand leftand rightteardrop profile faces.

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 inrespectively. The left finhas an outer facehaving a teardrop profile and a relatively flat inner face. The right fin (in the example) is the mirror image of the left fin.

shows the underside surface of a surfboardand 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 aswill 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.

Any center finswill, naturally, be mounted on the centerlineof the surfboard. In the neutral mounting position, the side fins,are mounted with an angle that points the longitudinal axis of the respective side fin toward the noseof 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. 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 aftof the nose of the surfboard.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 pointforward of the nose of the surfboard.

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

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 () or a slightly toed-in position (approximately 3-7 degrees which may be referred to as the manufacturer's preferred position) () but can be tailor made to other configurations.

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.

Typically, the amount of toe-out never exceeds the parallel line represented by the stringer or centreline of the board.

An example of a prior art removable finis depicted in. The fin includes a fin elementand a set of mounting elements. The fin elementis planar, extending along a fin plane. The fin elementincludes a leading edgeextending from a nosepast a tipof the fin to the tailand a trailing edgethat extends from the backof the mounting section to the tail. The mounting elementsare received into the fin box so that the fin elementprojects from the surfboard above the line. 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.

The particular shape of the fin depicted inis indicative only. Fins may be produced in a range of shapes.

schematically shows the finfrom the direction of the mounting elements. The mounting elementshave a mounting chord or axis. The mounting chordis 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, in the horizontal plane corresponding to the plane of the surfboard (i.e. perpendicular to the vertical fin plane) passing from the tipto the tail. As is shown in, for prior art fins, the mounting chordis parallel with the angle of attack.

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.

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. The finis a plane element extending along a fin plane and includes a toe end, tail, outer or rail faceand inner face. The fin also includes mounting elements. The fin may appear similar in side view to the side view of prior art finof. 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, the inner faceof the finis not straight. Instead, a rear sectionof the inner faceis curved outward, toward the rail face, moving in the direction toward the tail.

The effect of the curved tail profile is to displace the tail edgeaway from the planethat is tangential to the innermost portion of the inner face. The tail displacementmay be represented as a distance x mm. In one embodiment, the tail displacement, x, may be in the range of 1-7 mm, and in one specific embodiment, the displacement, x, may be in the range of 3-4 mm.

The portionof 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.

Optionally, the toe end of the finmay also include a curved profile that displaces the toe endaway from the tangential planeby a small amount z mm. The displacement z may be less than the displacement x.

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.

shows how the angle of attack, indicated by the solid linebetween the tipand tailis now angled relative to the longitudinal axis (mounting axis) set by the mounting chord(dashed line) passing through the mounting elements. 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.

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.

The finmay be considered as a left side toe-in fin. As viewed from above, if the finwere to be underneath a surfboard, the facewould be the rail-side face and the facewould be the centerline face. A right side toe-in fin would be the mirror image of fin.

shows an alternative embodimentof 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 attackis approximately 4 degrees to the mounting axis.

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.

shows a surfboardwith side fin mounting systems,schematically depicted in a neutral mounting position indicated by mounting axes,. 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, having an angle of attack of 2 degrees inward (as indicated by axes,) to the respective fin box mounting axis, will change the performance of the surfboard to having a more toed-in characteristic.

To produce a toed-out characteristic as depicted in, 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,converge forward of the nose of the surfboard.

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.

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 in-built toe angle.

shows an example of an asymmetric fin selection. The surfboardmay be fitted with one toed-in finhaving an angle of attack axisand one toed-out finhaving an angle of attack axis. The angles of attack converge at a pointwhich is displaced laterally of the centerlinewhich will create a direction based performance in the surfboard.

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.

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.

The surfboard fins may be produced from fiberglass/resin composites, plastic, or any suitable material. In one embodiment, a rectangular block of materialas shown inmay be the starting point. Profiles sections,,,may be removed along the height of the blockto produce a fin blockhaving the required horizontal cross section (). The profile sections may be removed by grinding, cutting or similar processes. The profiled fin blockmay then be cut into a fin outline, e.g. as shown in.

The amount of material that is removed for each profile section,,,will depend on the desired angle of attack for the fin. For example, for a greater angle of attack than shown in, the sectionmay not be removed at all to leave the side edge straight and the sectionthat is removed may be wider at the tail.

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.

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.