Surfboard fin

Abstract

Fin for a surfboard with a fin element which has a connecting element at its upper end for connecting the fin to a fin system of a board and a wing which is aligned perpendicular to the fin element and is located in the lower third of the fin element, preferably at its lower end, and generates lift when water flows around it.

Description

[0001] The present invention relates to an improved fin for a surfboard.

[0002] Surfing, kitesurfing, windsurfing, and SUPs are enjoying ever-increasing popularity. The latest trend involves foils, which are particularly used in windsurfing. These foils lift the surfboard out of the water while riding, creating a gliding effect on the foil, which consists of a front and rear wing. Physically, this can be explained by the Bernoulli effect, which is used in aircraft.

[0003] Despite these rapid developments, the classic surfboard for wave riding has remained virtually unchanged since the 1960s, apart from improved board materials and board shapes. It still consists of a relatively small board that doesn't fully support the surfer when stationary and is thus largely pushed underwater by the surfer's weight while waiting for a wave. It also consists of one or more fins at the tail of the surfboard, which can be used to adjust the surfing characteristics, such as turning ability, etc.

[0004] Surfing is considered the most difficult and physically demanding discipline. Paddling out through breaking waves, paddling toward a wave, and the so-called takeoff pose significant challenges for surfers at the beginning.

[0005] It is therefore the object of the present invention to improve a surfboard in such a way that paddling into a wave is made easier.

[0006] This problem is solved by the subject matter of the independent claims. Preferred embodiments are the subject matter of the subclaims.

[0007] The invention is based on the finding that the desired improvement can be achieved by modifying the fin design. In particular, the invention is based on the finding that a fin device with airfoils can replace the classic fin and lead to significantly improved paddling or planing characteristics of the board without noticeably negatively impacting the handling when riding waves.

[0008] The fin according to the invention facilitates paddling, as the tail of the surfboard experiences lift during paddling due to the angle of attack of the wing and the Bernoulli effect. This effect is greater when paddling into a wave due to the additional wave thrust and the correspondingly increased speed than when paddling out into the waves. This makes it easier, especially for inexperienced and older surfers, to achieve the necessary speed for a successful takeoff.

[0009] To ensure that the additional lift at the rear due to the wing does not have a negative impact on the board in terms of instability when riding a wave, the wings are preferably designed in such a way that the lift is significantly higher when the board is heavily loaded at the rear and tilted accordingly, than when the board is in motion, when the rider's weight is shifted further forward and the board is balanced or horizontal in the water.

[0010] This effect also provides support after each turn in the wave, where the rider initially shifts their weight backward to initiate the turn and now needs to pick up speed for the next turn. The speed build-up is shortened because, especially in the initial phase after the turn, when the rider's weight is further back on the board, the effect described above creates additional lift, thus shortening the braking effect caused by the tail dipping. As soon as the rider re-centers their weight on the board, the wing design causes the lift to decrease significantly, thus preventing it from negatively impacting the board's smooth running or turning ability.

[0011] Unlike foils, the idea isn't to lift the board out of the water and ride solely on the foils. Instead, the handling of a classic surfboard is virtually unaffected, simply improving the speed gain when paddling into the water and after turns.

[0012] The fin according to the invention itself represents the actual fin of the surfboard and can be easily and quickly mounted into the fin systems commonly available on the market. Common fin systems include FSC I & II, US-Box, Future, Powerbox, Slotbox, Starbox, and Tuttlebox, to name just a few.

[0013] The size and weight of the fin according to the invention are also comparable to conventional fins. Due to the rounded shape of the design, the risk of injury is lower than with the classic, relatively tapered fins.

[0014] The foil on a windsurf board, on the other hand, is significantly longer and heavier and completely changes the character of the board. Such a foil doesn't replace a fin and isn't itself a fin in the strict sense, but rather creates a new class of board with completely different dynamic handling characteristics than a surfboard without a foil.

[0015] The aim of the present invention is to provide a fin replacement for the mass market which does not result in any perceptible change to the rider's surfboard, neither in handling nor in terms of riding characteristics, apart from the aforementioned improved speed pickup.

[0016] The low weight and small size of the device according to the invention also lead to moderate manufacturing costs and thus to a real alternative to classic fins.

[0017] Another advantage is that the board with the mounted fin or several mounted fins can stand stably on a flat surface due to the wing at the end of the fin, which is not the case with boards with only one classic fin.

[0018] Preferably, the wing or airfoil is located at the very bottom of the fin, forming its end. The fin element that holds the airfoil is perpendicular to this airfoil and is mounted with its upper end in a fin box of a surfboard.

[0019] This preferably results in a T-shape of the fin, especially if the length of the fin element is approximately equal to the length of the wing.

[0020] The wing doesn't have to be positioned at the very bottom of the fin element, but can also be positioned slightly higher. In any case, it should be located in the lower third of the fin element, as tests have shown that this leads to better handling.

[0021] The wing can be split into two parts and extend to either side of the fin element. However, it is preferably formed as a single piece and forms the lower end of the fin element. Furthermore, it is preferred that the entire fin be manufactured as a single component to provide the necessary stability and enable a compact design.

[0022] Preferably, flow channels are also provided in the wing to guide the incoming airflow and improve handling. These channels are typically integrated into the surface of the wing, but can also be provided on the underside. The channels on the upper side preferably converge from front to back, which has been shown to have a positive effect on handling in tests. The channels on the underside, on the other hand, can run parallel to the fin element.

[0023] Preferably, the wing's pitch can be adjusted to the current, or one-piece versions with specific angles of attack are available. In tests, an angle of attack of 4 degrees has proven to be optimal. Generally, the angle should be between 0 and 25 degrees. This fine adjustment allows for ideal buoyancy during the various phases of surfing, depending on rider weight, board length, and wave shape.

[0024] Further preferred embodiments are the subject of the subclaims.

[0025] In the following, embodiments are described in more detail with the aid of drawings, which show: Figure 1 a perspective view of an embodiment of the fin according to the invention, Figure 2 a plan view of the embodiment of Figure 1 , Figure 3 a view of the illustrated embodiment from the front, Figure 4 an illustration to explain design differences when using three fins on a surfboard, Figure 5 a further embodiment of a fin according to the invention, and Figure 6 a surfboard with a mounted embodiment of a fin according to the invention.

[0026] Figure 1shows an embodiment of the fin 1 according to the invention. The fin comprises a fin element 2 and a support surface 3 consisting of two symmetrical halves 3a and 3b. At the upper end of the fin element 2 is a connecting element 4, which in the embodiment shown is a so-called FCS connecting contact. FCS connecting contacts represent one of the common variants for connecting fins to surfboards. Of course, this connecting element can be designed to be compatible with any established fin system.

[0027] It is clearly visible that the wing or airfoil has a steeply rising profile 5 in the front area, i.e. it is thickened and flattens out again towards the rear. The profile is essentially that of an aircraft wing. Due to the curvature in the upper area, the path for the airflow is longer than on the underside, which, based on Bernoulli's law, creates an upward force that leads to lift. The wing 3 is perpendicular to the main plane of the fin element 2, similar to an upside-down spoiler. The fin element is designed similarly to a conventional fin and accordingly has a concave curve 6 in the rear area, which is aerodynamically advantageous.In the illustrated embodiment, the length of the fin element from front to back is approximately equal to the length of the wing 3 (length here refers to the dimension along the board's longitudinal axis after the fin has been installed), whereby the wing 3 can protrude slightly at the front and back. Such an elongated fin element, which differs from conventional, slimmer fins, has proven to be aerodynamically favorable in conjunction with the wing. It also improves stability and design. The width of the wing (analogous to the board width after the fin has been installed in the board) in this variant roughly corresponds to its length, making the wing approximately square. The height (i.e., the length of the fin element measured from the fin box downwards) of the fin element is also kept within this range, resulting in an overall "cube-like" design.

[0028] Typical and preferred designs in terms of length / width / height (each in mm): Version L: 100 / 100 / 100 Version M: 100 / 70 / 70 Version S: 100 / 50 / 70 Version XS: 70 / 20 / 50

[0029] The fins are clearly comparable in height to standard fins.

[0030] The ratio of length to width of the wing is in the range of 1-2.5, with a ratio close to 1 being preferred.

[0031] The height to length ratio is preferably in the range of 1 - 0.7.

[0032] The wing 3 has a channel 7 on its upper side, which runs from front to back toward the fin element. The two upper channels thus roughly form a V. Such channels improve laminar flow and prevent turbulence. Such channels can also be located on the underside of the wing, resulting in a total of four such channels per fin, with the lower channels also being able to run parallel to the fin element.

[0033] Flow tests have shown that the combination of such channels, together with the illustrated wing profile and a fin element 6 approximately the length of the wing, leads to particularly favorable flow behavior. As shown, the wing 3 is preferably arranged at the lower end of the fin element, so that the entire fin has a T-shape.

[0034] Preferably, the entire fin is formed as a single piece and can be manufactured by printing, injection molding, or lamination. The wing 3 is perpendicular to the main plane of the fin element 2, but can be angled forward, i.e., rising toward the front. An angle of 4° has proven to be favorable; in principle, this angle should be between 0° and 25°.

[0035] Figure 2 shows a plan view of the fin design according to Figure 1 and shows, in particular, the course of the channels 7 on both sides of the fin element 2. The airflow around the fin element 2 flows from left to right during travel; accordingly, the front part 8 of the fin element is rounded to minimize water resistance. The total width of the wing in this embodiment is 100 mm. The wing is clearly approximately square.

[0036] Figure 3shows the wing again from above, showing additional channels 9 running along the underside of the wing. The height of the fin element 2 is also visible, in the range of a few centimeters; in the embodiment shown, this height roughly corresponds to the width.

[0037] This distinguishes the fin according to the invention from so-called foils, which have heights in the range of 70 cm - 100 cm. Foils are designed to lift a surfboard completely out of the water, enabling planing on the foil alone. The fin according to the invention, on the other hand, is designed to only provide a slight lift when paddling, but otherwise does not change the surfboard's handling.

[0038] Surfboards often have three such fins, although some riders prefer a single fin. When three fins are used, the two outer fins typically differ slightly in size and shape from the center fin. The center fin is the largest fin, and the two outer fins are mirrored in shape to the center fin.

[0039] In one embodiment, the fins are made of carbon fiber composites, preferably PA12 or PETG, each with a carbon fiber content.

[0040] Figure 4 shows the profile of fin element 2 for a center fin, as well as for a left and right fin. It is clear that the left and right fins are not identical in the profile of the fin element, but are each specifically designed for the corresponding side.

[0041] Figure 5shows an alternative embodiment of the fin according to the invention. This embodiment has no channels, and the length of the wing extends rearward beyond the length of the fin element. This embodiment can be used in particular when the wings are attached to the fin element with screws.

[0042] Figure 6 shows a surfboard with an inserted fin design, although only one fin is shown here. However, the use of two, three, or four fins is also possible. Even at high speeds, the fin does not lift the surfboard out of the water, unlike foils.

[0043] The classic foil consists of a front wing and a rear wing, also called a stabilizer. The two are connected by a fuselage. A mast is attached to this fuselage, which connects to the board via a mounting plate. A classic foil mast is typically between 70 cm and 110 cm high, the so-called "front wing" is between 850 cm and 950 cm, and the "back wing" measures between 335 cm and 340 cm.

[0044] In contrast, the fins presented here preferably have only one wing per fin, which provides lift. They require no fuselage and can be easily mounted on any of the three fin systems or fin boxes for surfboards available worldwide. The fins or slide fins according to the invention preferably have four so-called channels—two at the top and two at the bottom—which provide additional lift and stabilization through a special water passage. The slide fins can be between 8.5 and 9.5 cm high, 10 and 12 cm long, and between 10 and 12 cm wide, depending on the surfer's skill and weight. This makes them not only significantly more manageable but also considerably lighter than classic foils.

[0045] Essentially, two types of lift are created in water: static and dynamic. Static lift is created by the material selection (lower density than water). The primary lift (dynamic), on the other hand, uses effects similar to those found in airplane wings to generate the necessary lift.

[0046] This lift is achieved primarily by positioning the wing against the current when the tail of a surfboard is loaded. This is automatically the case when paddling, as a surfer places greater weight on the tail of the board during this phase.

[0047] Once the takeoff is complete and the board is surfing the wave, the weight distribution is balanced and the aforementioned tilting disappears. Accordingly, the buoyancy is reduced, which would otherwise be perceived as annoying during normal surfing. Additionally, and due to the wing profile, there is a lift due to the Bernoulli effect: due to the special geometry of the inventive slide fins, the water flows past faster above than below. This results in an upward force. This second lift component is weaker than the lift caused by tilting, which is positive because this lift continues during normal riding.

[0048] By tilting the wing, both effects and the phases of their impact can be influenced. In tests, an angle of attack of 4 degrees has proven advantageous.

[0049] One embodiment provides for the free adjustment of the angle of attack using a locking device. The blade can thus be rotated and finely adjusted around an axis perpendicular to the main plane of the fin element.

[0050] The additional "channels," which are preferably located on the surfaces of the slide fins, channel the turbulent flow (when paddling / surfing) and convert it into laminar flow. This reduces water resistance and achieves an optimal buoyancy ratio, making paddling into waves easier, even at low speeds (from approximately 5 km / h).

[0051] A trained surfer weighing 80 kg and with a 35-liter board can reach approximately 6-8 km / h while paddling (without the wave's thrust). Even during this phase, the fin supports the surfer thanks to its buoyancy, making long paddling sessions significantly more energy-efficient.

[0052] The biggest difference, however, is when paddling into a wave, where speeds are higher due to the wave's thrust. This paddling takes between two and ten seconds, depending on the surfer's position and strength. The wave pushes from behind, which can accelerate experienced surfers to speeds of up to 60 km / h, depending on the size of the wave.

[0053] During these seconds of paddling on the wave, the nose of the board must be above the water, which is achieved by shifting the weight backward on the board, hence the buoyancy at the rear of the surfboard. Otherwise, getting up on the board becomes impossible, and the classic beginner's mistake, also known as a "nosedive," prevents you from surfing the wave. Getting up is achieved by pushing the surfboard downward, in which the surfer jumps onto the board at the same time as pushing the board down. Here, too, the weight must still be placed at the rear of the board to build up enough speed so that the board completely clears the water and enters the planing phase on the wave.

[0054] When the board is in the planing phase and the surfer is standing still, the surfer shifts their weight forward again. They are now fast enough, as they are riding down the wave. During this phase, the fin provides very little lift.

[0055] As soon as the surfer reaches the bottom of the wave and starts a turn (back up the wave, also called a "turn"), they shift their weight back to turn the board. The innovative fins also support the surfer during this phase, allowing them to regain speed more quickly.

[0056] When the surfboard is on planing and the surfer shifts their weight forward, this causes the slide fins to point "downward," generating a slight downforce. This downforce can be adjusted through the design and can have a positive effect on the ride characteristics.

[0057] Since the fin according to the invention can, in one embodiment, selectively generate strong lift (tail loaded), weak lift (board horizontally / centrally loaded) and downforce (board front loaded), the rider has improved options for controlling the board speed that conventional fin designs do not offer.

Claims

1. Fin for a surfboard with a fin element which has a connecting element at its upper end for connecting the fin to a fin system of a board and a wing which is aligned perpendicular to the fin element and is located in the lower third of the fin element, preferably at its lower end, and generates lift when water flows around it.

2. Fin according to claim 1, wherein the fin element and the airfoil are formed as one component.

3. Fin according to one of the preceding claims, wherein the wing extends symmetrically on both sides of the fin element 4. Fin according to claim 3, wherein at least two flow channels are formed in the wing, preferably one flow channel at the top and one at the bottom on each side of the wing.

5. Fin according to one of the preceding claims, wherein the fin is made of carbon fiber composites, preferably of PA12 or PETG, each with a carbon fiber portion.

6. Fin according to one of the preceding claims, wherein the wing is designed such that, when inserted into a surfboard, it provides maximum buoyancy when the surfboard is tilted in the water due to loading of the stern and the buoyancy is significantly reduced when the surfboard is loaded substantially centrally.

7. Fin according to one of the preceding claims, wherein the airfoil has at least a length corresponding to the length of the fin element.

8. Fin according to one of the preceding claims, wherein the fin element is designed in its profile similar to a conventional fin, but has a length comparable to the length of the wing.

9. Fin according to one of the preceding claims, wherein the wing is adjustable in its inclination relative to the surfboard in order to be able to adjust the buoyancy behavior for different loads.

10. Fin according to claim 9, wherein the angle of attack is adjustable in the range of 0-25 degrees.

11. Fin according to one of the preceding claims, wherein the wing extends beyond the extent of the fin element both at the front and at the rear.

12. Fin according to one of the preceding claims, wherein the fin element has a height corresponding to commercially available surfboard fins depending on the application.

13. Fin according to one of the preceding claims, wherein the wing has an airfoil profile.

14. Fin according to claim 1, wherein the wing is subsequently mountable and is adjustable in its angle of attack relative to the flow.

15. Surfboard with at least one fin according to one of the preceding claims.

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