Technical field

The present document relates to a board for water sports provided with a variable rocker trim system. More particularly, the present disclosure relates to a windsurfing board provided with a variable rocker trim system.

Background

Windsurf boards in general are a planing hull and are subjected to the same forces and dynamics as any other planing hull. All planing hulls have an optimum angle of attack as they travel through the water. The more parallel a hull can travel to the surface of the water, the less it will disturb the water and the faster it will travel. In the case of wind surf boards the same principles apply.

A flatter overall hull curve is theoretically an optimum, but when a board travels too flat or parallel to the water it is subjected to resistance and force from the chop and waves far forward of the rider.

The further away from the rider, the forces are amplified by leverage, i.e. the greater distance causes a higher leverage. Heavier riders can overcome these forces by virtue of their weight, keeping the rear lower and increasing the angle of attack (nose/front of board higher). A lighter rider has less effect and is more subjected to the greater forces. One solution to reduce the lift in the tail section, is to narrow the width to create less lift allowing the tail to plain lower in the water and therefore increasing the angle of attack.

The front section of the board rides higher and will be subjected to less force by chop and waves. However, there are a number of problems associated with this, firstly an increase in the angle of attack increases drag affecting planing and top speed, and secondly a narrow tail is less stable at top speed.

For example a wider platform as opposed to a narrow platform floating in the water, the wider platform is inherently more stable.

Fin leverage is an additional force acting on the board. It is common knowledge that a wider tail is more stable than a narrow tail with an equal sized fin.

One of the ways board designers have tried to solve this problem is by having a wide tail but reducing the width on the underside of the hull using what is known in the industry as cutouts. This allows the theory of a stable wide tail on the deck of the board with a narrow tail on the bottom or hull of the tail. To a degree this works, however, it still is subjected to the problems and dynamics as discussed previously. It is a compromise for rider weight, sail size and wind strength all of which have an outcome for board trim. The term rocker describes how 'bent' (curved) a board is. Rocker is measured along the centre line on the bottom along the front and tail axis. For a windsurfing board, a wave board will have a lot more rocker (bend) than a slalom board because rocker determines board trim, how easy it is to turn and to a certain degree how 'safe' it is as water conditions deteriorate.

Summary

It is an object of the present disclosure, to provide a board or a trim system for the rocker of a board, which eliminates or alleviates at least some of the disadvantages of the prior art boards and trim systems.

The object is wholly or partially achieved by a board and a method according to the appended independent claims. Embodiments are set forth in the appended dependent claims, and in the following description and drawings.

According to a first aspect, there is provided a board adapted for planing in water, wherein the board comprises a hull and a deck, a front portion and a tail portion, said tail portion having a end part, and at least one fin box, wherein the fin box is arranged at a distance from said end part of the tail portion, wherein a section of the hull of the tail portion is cut at an angle upwards from a rear part of the fin box towards the end part of the tail part and at an angle to the end part, wherein the board further comprises at least one plate, having a first end and a second end, wherein the first end is attached to the deck of the tail portion, wherein said plate, in a first position, is aligned with and is a continuation of the deck such that an angle is created between the cut out section and the plate, and in that at least the end part of the plate is further moveable in relation the cut out section of the tail portion, when the plate is in a second position, such that the angle is adjustable.

The plate is thus attached to board to the rear of a windsurfer, standing with his or hers feet in the footstraps, on the board. This board, i.e. the board and the moveable or flexible plate, thus provides a variable rocker trim system (VRTS), i.e. a system for adjusting the curvature (or bend) of the board. The angle may thus be made bigger or smaller, depending on the desired performance of the board. This is advantageous since once a board, such as e.g. a windsurf board, has been designed and produced, it is very difficult to change the curvature, to achieve different characteristics of that board. The Variable Rocker Trim System may thus allow the rear of the board or plate to flex or be adjusted when under load. Depending on the tension of the plate the trim angle can thus be altered to suit rider requirements, i.e. to suit varying wind and water conditions. This board or system also provides for the possibility of using a wider tail, which gives the board more stability.

Instead of a fixed curve as current designs of boards have, the tail or plate on the VRTS board can thus be very easily adjusted to flex and therefore alter the trim. The placement of the plate also ensures that it is a very stable and reliable construction. Drag may be reduced when the angle of attack is increased, because the plate is allowed to flex and follow the surface of the water more parallel to it. As the rider sails over chop and waves more pressure may be applied to the rear of the board flexing the plate and increasing angle of attack allowing a more controlled and smoother ride. In high wind conditions more leverage is applied to the rear of the board by the rider. This can cause the front of the board to rise and instability due to too little of the tail in the water. These forces are generated by the sail and transmitted to the board by the rider. In these conditions the plate may be adjusted to flex less therefore allowing the board to trim lower. In light air where wind gusts and water conditions are easier the rider may choose to allow the plate to flex more thus enabling the board to ride further back and decrease wetted area for a greater top speed. At the same instance the plate is flexing and is relatively parallel to the water further reducing drag by decreasing the angle of attack.

According to one embodiment the first part of the plate may be fixedly attached to the hull. The plate may be attached to the hull by using any one of at least one screw, gluing the plate to the hull and molding the plate to the hull.

The plate may for instance be glued with an epoxy resin.

By molding the plate to the hull a seamless continuation of the hull may be provided.

The board may be provided with at least one plug for receiving said at least one screw, wherein said at least one plug is arranged such that it is substantially aligned with the fin box. By using screws and plugs the plate may be detached from the board, to be removed, or replaced, for instance in case it has been damaged, or if another type of plate is to be used, i.e. having different stiffness or flexibility.

According to one embodiment the first part of the plate may be pivotably attached to the hull. By having a plate which is able to pivot the need for having a resilient or flexible plate may be reduced. The adjustment equipment may then instead be provided to hold the plate in place, or pull the plate towards the hull. The plate may, however still be made of a flexible or resilient material.

The deck may further be provided with a cut out portion arranged at the tail portion, such that the tail portion comprises a tapered portion.

According to one embodiment of the first aspect the plate may be resilient. This means that the plate may inherently flex or be biased towards (or from) the hull of the board.

The tail portion may be provided with adjustable means or adjusters for moving said second part in relation to the cut out section.

According to one embodiment the adjustable means or adjusters are arranged at a distance from the end part of the tail portion and wherein said means extend from the deck to the hull.

The adjustable means or adjuster may comprise a screw.

The screw or adjustable screw may thus be arranged to extend from the deck of the board to the hull, i.e. substantially through the tapered portion of the tail, and to abut the second part of the plate. This means that when the screw is rotated upwards, the second part of the plate moves towards hull of the board, i.e. the angle becomes smaller, and when the screw is rotated to move downwards the second part of the plate moves from the hull, thus creating a larger angle between the plate and the hull. In most cases and adjusting screw can be fitted from the deck of the board above the flexible plate and at 90° to it through the hull and exiting above the plate allowing adjustment to the travel or flex of the plate. When the screw/bolt adjuster is against the plate flex is thus minimal and as the screw is raised the plate can flex more, and this allows an infinite amount of adjustment and travel of the plate until the travel of the plate is taken up by its own tension.

The second part of the plate may extend or protrude beyond the end part of the tail portion. The plate may be made from a flexible material, comprising any one of epoxy carbon fibre, carbon fibre and fiberglass, plastics materials, fireglass or G1 O, or mixtures thereof.

The plate may a thickness in the range of from 1 mm to 4 mm, as seen in a side view.

According to one embodiment of the first aspect the board may be any one of a windsurfing board, a wave surfing board and a stand up paddle (SUP) board.

According to a second aspect there is provided a method for adjusting a rocker of a board adapted for planing in water, wherein the board comprises a hull and a deck, a front portion and a tail portion, said tail portion having a end part, and at least one fin box, wherein the fin box is arranged at a distance from said end part of the tail portion, wherein a section of the hull of the tail portion is cut at an angle upwards from a rear part of the fin box towards the end part of the tail part and at an angle to the end part; and at least one plate, having a first end and a second end, wherein the first end is attached to the deck of the tail portion, wherein said plate, in a first position, is aligned with and is a continuation of the deck such that an angle is created between the cut out section and the plate, wherein the method comprises the step of moving the at least the end part of the plate in relation the cut out section of the tail portion, to a second position, such that the angle is adjusted.

Brief Description of the Drawings

Embodiments of the present solution will now be described, by way of example, with reference to the accompanying schematic drawings in which:

Fig. 1 is a schematic bottom view of a board tail.

Fig. 2 is a schematic cross sectional views along the line C-C of Fig. 1

Description of Embodiments

Fig. 1 illustrates a tail portion 2 of a board 1 , from the hull 10 side, i.e. a bottom view of the board. The tail portion 2 has end part 13, marked with a dotted line in Fig 1 . A fin box 3 is arranged at the tail portion for attaching a fin to the board. Alternatively the board is provided with multiple fin boxes (not shown). The fin box may be of any conventional type such as a so called tuttle box or power box. On the deck side 1 1 the board may be provided with at least one foot strap 6, wherein the user may insert his or hers foot when using the board.

At least on plate 4 is attached to tail portion 2 of the hull 10. The plate is thus attached to board rear of a windsurfer standing on the board, i.e.

substantially rear of the foot straps. The plate 4 has a first portion 4a and a second portion 4b. The plate is constructed and attached such that it allows for a fin to be placed correctly in the fin box, this means that it may either be attached to the rear side of the fin box 3 or be provided with a cut out section 9 such that it does not interfere with the fin box 3 and the fin (not shown) attached therein/thereto.

According to one embodiment the first portion 4a is fixedly attached to the hull 10. The method of attachment is either by, gluing the plate to the hull using epoxy resin (not shown), or moulding the plate with the hull at one time creating a seamless continuation of the hull (not shown). Alternatively the first portion is attached by using screws 8, which may alternatively be screwed into plugs 7 (or directly into the board). The plugs 7 are put into the hull 10 of the board. This means that the plate can be removed or replaced.

According to an alternative embodiment the first part 4a of the plate is attached such that it can pivot, by means suitable to allow for a pivot movement, such as hinge (not shown).

According to one embodiment the second part 4a of the plate protrudes or extends beyond the end part 13 of the board.

According to another embodiment the second portion 4b may also be arranged in line with the end part 13 (not shown), or alternatively ending before the end part 13 (not shown).

The length of the plate may be varied, and is in one embodiment in the range of from 50 to 150 mm. The plate length can be varied depending on board widths, bottom curve design and for the intended design or function criteria.

The plate 4 may be a flexible plate, i.e. made of material that is resilient or flexible. According to one embodiment the flexible plate can be constructed from a variety of materials using epoxy or other resins. These materials may include, but are not limited to: carbon fibre, carbon fibre and fibreglass, plastics of suitable types, fireglass and G1 O. According to an alternative embodiment the plate is made of a mixture of these materials, or a laminate. The plates may also be moulded or machined using the above materials. The material of the plate may thus allow the plate to move upwards or be resilient (biased) towards or from, the hull 10.

According to one embodiment the thickness of the plate, as seen in a side view in Fig. 2, may be in the range of from 1 mm to 4 mm. The thickness may for instance be varied depending on the flexibility required of the plate.

According to one embodiment the plate or plates may be tapered as seen in a side view. This may provide for different performance

characteristics. The plate may be tapered such that the second part 4b is narrower than the first part 4a, as seen from a side view in Fig. 2.

According to one embodiment the plate, or at least the second part 4a thereof, may have a shape that substantially corresponds to the shape of the board, i.e. as shown in Fig. 1 . According to an alternative embodiment the plate may have any shape that provides the desired characteristics.

According to one embodiment the board is provided with two or more plates (not shown). These plates may be placed forward of the fin box (or boxes) and to each side.

As illustrated in Fig. 2 a section 15 of the hull 10 is cut at an angle upwards (i.e. toward the deck 1 1 ) starting from a rear part 14 of the fin box 3 (or boxes) and at an angle to the end part 13 of the tail 2.

The tail portion 2 may further be provided with a cut out portion 16 at the deck 1 1 side, i.e. have a tapered shape or section 17.

The plate 4 may be arranged such that it is in a first position (as shown in Fig. 2) aligned with and is substantially a continuation of the overall bottom curve of the hull 10.

An angle a is created between the plate 4 and the cut out section 15. The angle a can be adjusted by moving the plate 4 to a second position (not shown) either upwards, i.e. towards the hull 10 or downwards, i.e. away from the hull 10 as seen in a side view of the board.

The adjustment of the angle a, or that is the movement of the plate, or even the movement of the second portion 4b of the plate may be achieved by adjustable means or an adjustment equipment that is arranged at the tail portion 2. These means or equipment may also be called "adjuster" in the present disclosure.

According to one embodiment the means or equipment comprises an adjusting screw, which can be fitted from the deck 1 1 of the board above the flexible plate 4 and at 90° to it through the hull and exiting above the plate allowing adjustment to the movement or flex of the plate. When the screw/bolt adjuster is against the plat flex is minimal and as the screw is raised the plate can flex more this allows an infinite amount of adjustment and travel of the plate until the travel of the plate is taken up by its own tension.

The adjuster may also comprise other types of equipment that would for instance allow the user to adjust the rock trim during sailing.

According to one embodiment the plate may be arranged such that is pivotable, e.g. by a hinge connection between the hull and the first part 4a. In this embodiment an adjuster may alternatively be arranged and designed to pull the plate towards the hull for varying the angle a (not shown).

According to an alternative embodiment the plate is arranged to move freely under its own tension. Certain uses may not require any adjustment as in the case of stand up paddle windsurf boards or windsurf wave boards.

In the embodiment of two (or more plates) these may either be provided with individual adjusters, a common adjuster or no adjuster at all. This application would be useful for wave board and other surf craft where different tensions or other factors may require the plate or plates to be moved from the rear.

On a wave board a flatter overall hull curve may be used to allow early planning and speed. As the hull is rolled onto its rail to initiate a turn the pressure increases onto the plate on that side, flexing it upwards and increasing the hull curve allowing the board to be turned more easing.

In a straight course of sailing the pressure is reduced allowing the plates to straighten and therefore reduce the curve giving the hull a straighter curve and a higher speed.

This application and placement can also be used on slalom, speed or other styles of board where fin placement rearward is an important consideration for the boards performance characteristics. In some applications two separate adjustment screws may be used.