AU2012101791A4 - Dynamic fin system - Google Patents

Abstract

Abstract A dynamic fin system for water craft that has at least one base member (30) affixed to the underside of a water craft (6), a spindle (31) which is secured to the or each base member (30), pivotable about a longitudinal axis of rotation, means for limiting the pivotable range of motion of the spindle, at least one torsion spring, a means (32) for securely retaining the spindle (31) and the or each torsion spring, and at least one fin (01) affixed within or to the spindle (31) which pivots about said axis of rotation in response to pressure upon the or each fin (01) for providing maximum lift when the water craft is in motion and maximum depth (in fluid) when turning thereby providing enhanced speed and control of the water craft.

Description

AUSTRALIA INNOVATION SPECIFICATION DEEP ORANGE DESIGN DYNAMIC FIN SYSTEM (DFS) Inventor: Neil Waldbaum THE INVENTION IS DESCRIBED IN THE FOLLOWING STATEMENT 1 A DYNAMIC FIN SYSTEM FOR CONTROL OF WATER CRAFT Field of the invention This invention relates to fins for surfboards, wind-surfers, sail-boards, kite-boards, wave-skis, paddle-skis, wake-boards, boats, yachts and other finned water craft. Background of the invention [0001] There are various fin designs and configurations that are intended to provide control of the water craft by the use of different shapes and cross sections of fins that affect the flow of water underneath and around the craft. The majority of fins are fixed and static and do not respond significantly to changes in the forces they encounter in the water. There are a number of cases where fins are incorporated into mechanisms that are designed to move or rotate dynamically, however these fins are generally integral to the mechanism and cannot be exchanged by the user, rendering the user no choice regarding the fin shape or size to suit their personal preference or environment. [0002] This invention presents a system of affixing standard fixed fins to the water craft via a mechanical assembly that causes the fins to imitate the natural way marine animals, such as sharks & dolphins, utilise their pectoral fins to control their movement and manoeuvre in the water. The animal will change the angle of its fins in relation to its body, to create lift or drag, in order to turn on the fin as a pivot, or to increase speed.

2 [0003] It would be advantageous to provide a dynamic fin system that overcomes at least some of the problems of the prior art. [0004] It would also be advantageous to provide a dynamic fin system that affords the user a greater choice in the type of fins that can be used with water craft. [0005] It would be of further advantage to provide a dynamic fin system that affords the user better performance qualities than conventional fin systems. [0006] t would be advantageous therefore to provide a dynamic fin system that enhances the speed and manoeuvrability of water craft. [0007] The invention may be applied to any water craft, however for the purpose of explanation this description will refer to the application of the invention to a surfboard. [0008] Accordingly there is provided a dynamic fin system for water craft comprising at least one base member affixed to the underside of a water craft; a spindle which is secured to the or each base member, pivotable about a longitudinal axis of rotation; means for limiting the pivotable range of motion of the spindle; at least one torsion spring; a means for securely retaining the spindle and the or each torsion spring; at least one fin affixed within or to the spindle which pivots about said axis of rotation in response to pressure upon the or each fin for providing maximum lift when the water craft is in motion and maximum depth (in fluid) when turning thereby providing enhanced speed and control of the water craft.

3 [0009] In especially preferred embodiments of the invention the dynamic fin system can be affixed to the water craft using proprietary means such as standard fin plugs and fins boxes. [0010] In other preferred embodiments of the invention the or each fin can be affixed to the spindle using the fin's proprietary means of affixing itself to standard fin plugs or boxes. [0011] In other preferred embodiments of the invention a winglet or side foil may be incorporated into any one of the moving components to provide additional grip in the water and assist in preventing the water craft sliding out of control. [0012] There is also provided a dynamic fin system as described with reference to the accompanying drawings. Description of the drawings [0013] Figure 1 illustrates the first of two embodiments whereby the invention is mounted on a surfboard. In the first embodiment of the invention the mechanism is embedded into the underside of a surfboard and fixed in place with resin or other similar material. [0014] Figure 2 is an exploded view of the first embodiment and mounting method illustrated in Figure 1. [0015] Figure 3 is an illustration of a second embodiment and method of mounting the invention on a surfboard. In this method the apparatus incorporates various standard mounting components. [0016] Figure 4 is an exploded view of the second embodiment of the invention illustrated in Figure 3. [0017] Figure 5 is a view of the underside of a surfboard with the apparatus installed with two side fins, shown in the natural resting position.

4 [0018] Figure 6 is the same view with the two side fins in the maximum cant angle position. [0019] Figure 7 is a cut away view of the Spindle and Base showing the Rotation Limiting Features of each component. [0020] Figure 8 is a cross section of the apparatus showing the means for limiting the rotation from the natural resting position. [0021] Figure 9 is a cross section of the apparatus showing the means for limiting the rotation in the maximum cant angle position [0022] Figure 10 is a view from the front of the underside of a surfboard with a pair of Modified Fins in the natural resting position. [0023] Figure 11 is the same view as Figure 10 with the Modified Fins at the maximum cant angle position. [0024] Figure 12 is a view showing the use of an integral fin. [0025] Figure 13 is the front view of the apparatus in Figure 12 in its natural resting position. [0026] Figure 14 is the front view of the apparatus in Figure 12 in its maximum cant angle position. [0027] Figure 15 is a view showing another embodiment of the invention incorporating the use of an additional Winglet affixed to a moving part of the apparatus. [0028] Figure 16 is the front view of the apparatus in Figure 15 with the fin in its natural rest position. [0029] Figure 17 is the front view of the apparatus in figure 15 with the fin in its maximum cant angle position [0030] Figure 18 is a front view of a surfboard showing the cant angle of a side fin denoted with the symbol "a*".

5 Description of Dreferred embodiment [0031] The invention is based on a standard multi-fin configuration of foil sectioned fins for a finned surfboard or other craft. Any additional fins may be statically fixed to the board using conventional methods. The invention relates primarily to the two side fins wherein each fin is affixed to a mechanical assembly that is hinged on a longitudually oriented spring loaded axle, or other elastic component, that allows the fin's angular position to be increased or decreased by the pressure of water generated by the direction of travel, or force exerted by the rider in the process of manoeuvring the craft. [0032] The apparatus' natural resting position relative to the surfboard upon which it is affixed or integrally formed, is such that the fin is substantially perpendicular to the underside of the surfboard's surface (referred to hereafter as the "deck"), as it would be in the case of a standard or conventional surfboard. This angle is known as the cant angle and is generally around 50 in the direction of the closest deck edge, which is similar to the cant angle of a standard fixed fin on a standard surfboard. The apparatus is designed to rotate the fin at its base to vary its cant angle in relation to the speed and force of the water flowing past it. The maximum cant angle would bring the fin to an angle which is parallel, or almost parallel, to the deck of the board. When in this position the fin will be offset from the deck, not contacting it, allowing water to flow freely around the fin and between the fin and the deck. In this position the fin will provide maximum lift when the surfboard is travelling forward and maximum depth when turning. [0033] The spring tension on the axle is selected to keep the fin rigid enough to not move under low speed or low force, but flexible enough to respond to the change in water pressure on the fin when the surfer is making a turn or manoeuvring. When pressure is reduced, the apparatus 6 will return the fin to its natural resting position. Different spring tensions will deliver different performance results, depending on the skill of the rider and the type or size of the wave ridden. [0034] When the board is at rest, or moving slowly in the water, the fins are in a position that is substantially perpendicular to the deck, and held in place by the tension of the spring, against rotation limiting features on the apparatus. [0035] As the board gains speed in the water, the pressure and flow of water over the foil shape of the fins causes the apparatus to pivot and rotate the fin outwards away from the centre of the board, on an axis running parallel to the base of the fin (and longitudinally along the length of the deck), until enough speed is reached to bring the fin to a position where the fin's rotation is stopped by rotation limiting features on the apparatus. This is the maximum cant angle position, which is substantially parallel to the deck. In this position the fin creates additional lift to the board, reducing drag and increasing speed and manoeuvrability. [0036] As the board slows, the pressure on the fin is reduced and the apparatus will be returned to its natural resting position by the spring. [0037] When the rider exerts weight or pressure on one side of the board in order to turn, the directional flow of water against the fin will cause the apparatus to rotate the fin on the turning side to be angled into the water, increasing its cant angle towards the maximum cant angle. In this case the opposite fin, being subjected to the same directional force from the water, will be forced to return to its natural resting position. This allows the fin on the turning side of the board deeper penetration into the water, giving the surfer a greater degree of control of the craft. [0038] The apparatus may include a protruding winglet or wing shaped flange to help prevent the craft from sliding or losing grip in the 7 water when it is in a turn and the fin is at a greater than normal cant angle. Such a protrusion may be perpendicular or at another angle to the fin and will rotate in unison with it to maintain its relative position to the fin. [0039] The apparatus may be affixed to the board by embedding components into the body of the board or formed integrally with the board or water craft to reduce additional hydrodynamic drag that its bulk may create. In another embodiment it may be removeably affixed by an external component that fits into standard fin mount mounting hardware commonly known as "fin boxes". This added convenience allows the user to fit and remove the system on a board with standard fin mounting hardware. [0040] The fin may be a standard removable fin that fits into standard mounting features on the apparatus itself, or it may be integral to the apparatus itself. [0041] All the components are designed to be hydrodynamic to reduce the effect of drag that the added bulk of the apparatus will introduce. [0042] The following descriptions will refer to the components used in the method of affixing the apparatus to a water craft which in this example will be a surfboard. [0043] The Base (30) serves to hold the components together and attach the apparatus to the underside, or deck, of the surfboard (06). It also incorporates a Rotation Limiting Protrusion (37) that limits the angular rotation of the fin.

8 [0044] The Spindle (31) serves two main functions; it serves as the component to which a standard surfboard fin (01) is attached and it serves as the axle that allows the fin to rotate on its axis thereby increasing and decreasing the cant angle (12). The Spindle (31) is fixed to the Base (30) by the retaining Caps (32) that are held in position by mounting screws (05) or other fastening method. The Spindle (31) has a Rotation Limiting Depression (38) that correspondingly aligns with the Rotation Limiting Protrusion (37) on the Base (30) [0045] Standard surfboard fins (01) that have one or more Mounting Tabs (12) sit in appropriately sized mounting holes (35) on the Spindle (31), that are similar to those found in standard mounting hardware (03), and are locked in place by grub screws (04) in a similar manner as to how they would be locked into the standard mounting hardware (03). [0046] At least one and preferably two torsion springs (33) are longitudually mounted inside the Caps (32) at either end of the Spindle (31) along its axis and are fixed in a pre-torsioned state between a point on the Spindle (31) and a point that is constant in relation to the Spindle's rotation. This point may be on the Base (30) or on the Cap (32), depending on which preferred embodiment of the invention is employed. [0047] When water pressure is applied to the fin (01) in the desired direction, as a result of increasing speed or a turning manoeuvre, the fin (01) will cause the Spindle (31) to rotate on its axis, increasing the fin's cant angle a* (12), and further torsioning the spring (33). [0048] This rotation will continue until the surface of the Rotation Limiting Feature (39) on the Spindle (31) engages the corresponding Rotation Limiting Feature surface (41) on the Base (30), stopping the rotation.

9 [0049] When the water pressure is reduced the spring will return the Spindle (31) to its natural state, and will be stopped by the corresponding Rotation Limiting Features surfaces(38 & 40) on the opposite side of the feature, allowing it to rest at its starting cant angle aO (12). [0050] While a standard surfboard fin (01) can be used in the system, control can be further enhanced by using a fin that incorporates a modified tip (07) that is bent or curved. The bend is angled to point inward, opposite to the direction of the fins rotation, so that when the fin is at its maximum cant angle the bent portion of the fin helps prevent the water craft from "sliding", therefore providing a greater degree of control. [0051] An additional method of attaching a fin may incorporate a fin that is integrated into the Spindle as a single component (08) comprising all the features of each component, but eliminating all joins and seams that may introduce hydrodynamic friction. [0052] A further enhancement may include a Winglet (11) that is fixed, or integrated, into the side of the Spindle that performs a similar function to the modified tip fin (07), allowing standard fins to be used with the same benefit. [0053] Those skilled in the art will recognise that other methods of configuring the various components and attributes of the dynamic fin system described and illustrated herein are possible and fall within the scope of the present invention and may be incorporated without departing from the scope of the present invention. Further that the present invention disclosed herein may be suitably modified or adapted to a multitude of uses which fall within the scope of the invention as claimed. The drawings and description of the preferred embodiments of the present invention are not to be considered limiting and it is the desire of the 10 applicant to claim all aspects of the invention that fall within the scope of the claims and specification.

Claims (5)

1. A dynamic fin system for water craft comprising: - at least one base member affixed to the underside of a water craft; - a spindle which is secured to the or each base member, pivotable about a longitudinal axis of rotation; - means for limiting the pivotable range of motion of the spindle; - at least one torsion spring; - a means for securely retaining the spindle and the or each torsion spring; - at least one fin affixed within or to the spindle which pivots about said axis of rotation in response to pressure upon the or each fin for providing maximum lift when the water craft is in motion and maximum depth (in fluid) when turning thereby providing enhanced speed and control of the water craft.

2. The dynamic fin system of claim 1 where the system is affixed to the water craft using proprietary means such as standard fin plugs and fins boxes.

3. The dynamic fin system of claim 1 wherein the or each fin is affixed to the spindle using the fin's proprietary means of affixing itself to standard fin plugs or boxes.

4. The dynamic fin system of any of the preceding claims wherein a winglet or side foil is incorporated into any one of the moving components to provide additional grip in the water and assist in preventing the water craft sliding out of control.

5. The dynamic fin system as described in the drawings.