SE540401C2

SE540401C2 - Device and method for improving sail twist

Info

Publication number: SE540401C2
Application number: SE1750178A
Authority: SE
Inventors: Larsson Torbjörn
Original assignee: Torbjoern Larsson
Priority date: 2017-02-21
Filing date: 2017-02-21
Publication date: 2018-09-11
Also published as: WO2018153754A1; EP3585680A1; SE1750178A1

Abstract

The present invention relates to a device for improving sail twist, intended to be connected to a mast and a batten of a sail. The device comprises an outer tube (5) comprising a circumferential wall (15) and an aperture (35) in the wall. The device further comprises an intermediate tube (2) adapted to be arranged rotationally locked to the mast, comprising a circumferential wall (12) arranged at least partially inside the outer tube (5). The intermediate tube (2) further has an aperture (22) in the wall (12) comprising a straight portion (32) and at least one angled portion (42). Furthermore, there is a spring means (6) arranged around at least a part of the intermediate tube (2), contained at least partially inside the outer tube (5). The outer tube (5) is adapted to be rotatably arranged around the intermediate tube (2). The aperture (22) in the intermediate tube (2) is adapted to be connected to a batten extending through the aperture (35) in the outer tube (5).

Description

DEVICE AND METHOD FOR IMPROVING SAIL TWIST Field of the invention The present invention relates to a device and a method for improving the twist and draft profile of a sail.

Background of the invention The wind acting on a sail driving a sailing craft, such as a windsurfing board or a sailing boat, is a combination of two types of wind; true wind and headwind. True wind is the wind experienced by a stationary observer, this wind varies exponentially with the altitude above the water. Headwind is the wind caused by the velocity of the boat, and the vector sum of these two types of wind is called apparent wind. Because of the exponential variation of the true wind, the apparent wind will act more from behind the sail the higher up you get along the height of the mast. It would hence be preferable to have one profiled draft for low winds and speeds, and one profiled draft for higher winds and speeds, twisted along the height of the mast.

Most of the windsurfing sail manufacturers today use strong downhaul tension. This results in a loose leech tending to be floppy. In lower winds this loose leech is ineffective and will not produce much power. In strong winds and high speeds, the leech will be more or less tensioned and somewhat twisted, but it is difficult to achieve a profiled draft for the top part of the sail and still have it twisted.

Another issue today is that the mast bends to leeward in strong winds. This results in that the twist of the sail decreases, which is the opposite of what is preferred in strong winds. The bending of the mast to leeward also results in an increase of draft, giving the sail more power, which is not desirable in strong winds when considering being able to hold the sail. Rather than a decrease in twist and increase in draft the opposite would be preferred in strong winds; an increase in twist and a decrease in draft.

Summary of the invention It is an object of the present invention to alleviate at least some of the mentioned drawbacks of the prior art and to provide a device and a method for achieving suitable draft and twist properties in a sail, both for lower winds and speeds and for higher winds and speeds. One of the objects is to enable twisting and inducing a profiled draft at the same time in strong winds and speeds. Another object is to achieve a profiled draft without twist for lower winds and speeds. These and other objects are achieved by the present invention.

The present invention is based on the realization that inclining at least the top batten in strong winds lowers the tensile stress in the sail cloth so that the top portion of the sail can twist. It is also based on the realization that bending of the mast to leeward can be decreased by at least partially taking care of the load in the upper portion of the sail by torsion in the mast. It is further based on the realization that by limiting the sail’s ability to twist in lower winds, an increased draft can be achieved.

According to a first aspect of the present invention a device for improving sail twist is provided. The device is intended to be connected to a mast and a batten of a sail. The device comprises an outer tube having a longitudinal axis, and said outer tube comprises a circumferential wall and an aperture in said wall. The device further comprises at least a first intermediate tube adapted to be arranged rotationally locked to said mast. The first intermediate tube comprises a circumferential wall, arranged at least partially inside said outer tube, the first intermediate tube having a longitudinal axis arranged so that said longitudinal axis coincides with said longitudinal axis of said outer tube. Said first intermediate tube further has an aperture in said circumferential wall comprising a straight portion arranged perpendicularly to said longitudinal axis, and at least one angled portion extending from the straight portion at an angle of between 1-90<º>. The device further comprises spring means arranged around at least a part of the first intermediate tube and contained at least partially inside the outer tube. Said outer tube is adapted to be rotatably arranged around said first intermediate tube, and said outer tube is further adapted to be arrangeable in a neutral position in which said spring means is not loaded and said aperture of said outer tube is aligned with at least a part of said straight portion of said aperture of said first intermediate tube. Said aperture in the first intermediate tube is adapted to be connected to a batten extending through said aperture in said outer tube.

According to one exemplary embodiment, the batten may be connected to the outer tube, so that rotation of the batten around the mast causes rotation of outer tube, and vice versa. The batten is typically mounted so that it goes through the aperture in the outer tube, and connects to the aperture in the intermediate tube. In low winds the spring means is not loaded, which limits the degree to which the outer tube can rotate, so that the batten can move along the straight portion of the aperture in the intermediate tube only. In other words, in low winds the force from the wind is not sufficient to load the spring means to such an extent that the outer tube can rotate so that the batten can move along the angled portion of the aperture in the intermediate tube. This limits the twist of the sail while still allowing a full draft. It is the length of the straight portion which determines the shape of the draft by determining the angle of the leading edge.

In stronger winds the spring means is loaded so that the outer tube and batten can rotate further around the mast, which results in that the batten can move along the at least one angled portion of the aperture in the intermediate tube. This causes the end of the batten closest to the mast to be elevated compared to when moving along the straight portion of said aperture, which causes the whole batten to be inclined. The inclination implies that the angle between the mast top and said batten is increased. This results in the tensile stress in the sail being decreased, so that the top portion of the sail can twist, as desired in strong winds, and still have a draft.

According to one exemplary embodiment of the present invention, said device is adapted to also be connected to a sail, such as a sail cloth, that is adapted to be connected to a mast, a sail and a batten of said sail.

According to one exemplary embodiment of the present invention, a telescopic batten end may be connected between said batten and said intermediate tube. This has the advantage that the device can be used with different battens and sails.

According to another exemplary embodiment of the present invention, the batten is directly connected to the intermediate tube and telescopically attached to the outer tube in a roller connection. This has the advantage that an extra part in the form of a telescopic batten end is not needed.

According to an exemplary embodiment of a device according to the present invention, said spring means is a spring. According to another exemplary embodiment, the outer tube may further comprise at least one connection point to said spring means so that rotation of said outer tube causes loading of the spring means.

According to one exemplary embodiment, the device includes a set of springs of various stiffness and with adjustable length. This is advantageous since the desired stiffness of the spring varies between sailors and wind registers, and the spring means should be chosen based on these conditions. Delivering a device with a set of springs gives the users the opportunity to choose and adjust this feature on their own.

In an exemplary embodiment of a device according to the present invention, the outer tube is further provided with at least a first flange extending radially outwards from the circumferential wall of the outer tube. This provides support for the batten connected to the device. According to another exemplary embodiment, this flange is provided with an aperture to which the batten can be connected. This promotes the inclination of said batten, since a rotational moment is created with the additional connection point at the end portion of the batten.

According to another exemplary embodiment, the device may be provided with a second flange extending radially outwards from the circumferential wall of the outer tube. This second flange may also be provided with an aperture to which a batten can be connected. When two flanges with apertures are provided, these apertures may be located so that a pin or screw can extend through both of them and through the batten to be connected. Providing two flanges is advantageous since it further stabilizes the connection between the batten and the device.

According to one exemplary embodiment, the aperture(s) in the flange(s) may have an elongated shape extending at an angle from the longitudinal axis of the device, so that the connection point between the batten and the flange(s) may move within the aperture(s). An arrangement of this type may help with finding the correct inclination of the batten.

According to another exemplary embodiment, the device may be provided with a first and a second flange spaced apart at a distance appropriate for positioning a batten between said flanges. According to another exemplary embodiment, said first and second flanges are arranged essentially parallel to each other. Such an arrangement further helps with stabilizing said batten.

By the term “extending radially outwards” when describing two flanges is meant to understand that a central line between the two flanges is aligned with an extension of the radius of the outer tube.

According to another exemplary embodiment, the device according to the present invention may further comprise an inner tube, also having a longitudinal axis. The inner tube should be arranged inside the first intermediate tube, in a way so that the longitudinal axis coincides with the longitudinal axes of the intermediate and outer tubes. It may be adapted to be rotationally locked to the intermediate tube. It may also be adapted to be rotationally locked to the mast on which the device is to be mounted. When an inner tube is present, it can act as the structural backbone of the device to which the other components can be attached in different manners. This is advantageous since less or no modifications have to be made to the mast the device is to be mounted on, compared to when all of the components have to be in direct connection to said mast.

According to another exemplary embodiment, the inner diameter of the inner tube fits the diameter of the mast on which the device is to be mounted. This enables simpler mounting of the device, since filling of an extensive gap between said mast and said inner tube is not necessary. According to one exemplary embodiment, the inner diameter of the inner tube is slightly more than 28 mm. This is preferred since this is a common diameter of the top of a wind surfing mast.

According to an exemplary embodiment, the device may further comprise a second intermediate tube. This second intermediate tube also has a longitudinal axis, and the tube should be arranged at least partially inside or outside said first intermediate tube. The longitudinal axis of the second intermediate tube should coincide with the longitudinal axes of the different tubes of the device. Similarly to the first intermediate tube, the second intermediate tube comprises a circumferential wall and an aperture in said circumferential wall. The aperture may comprise a straight portion arranged perpendicularly to said longitudinal axis, and at least one angled portion extending from the straight portion at an angle of between 1-90<º>. The second intermediate tube is to be arranged so that the respective apertures of the first and second intermediate tubes at least partially overlap. The tubes may be arranged so that they can be rotated and locked in relation to each other, in order to adjust the overlap of their respective apertures. The advantage with having a second intermediate tube arranged so that it can be rotated and locked in relation to the first intermediate tube is that the length of the straight portion of the overlap of their respective apertures can be adjusted. This is advantageous since the length of this straight portion is what determines the profiled draft of the sail in low winds and speeds, when the batten can only move along this straight portion.

In an exemplary embodiment of the present invention, the angled portion(s) of the aperture(s) in the intermediate tube(s) extend from the straight portion of said aperture(s) at an angle of between 10-80<º>. In a more preferred embodiment said angled portion(s) extend at an angle of between 20-70<º>. This is preferred since it gives an appropriate degree of inclination of said batten in relation to the rotation of said batten around said mast.

In one exemplary embodiment the angled portions both extend at the same angle, and in another exemplary embodiment they extend at different angles. Extension at the same angle is advantageous since it gives the same draft and twist properties no matter in what direction said batten rotates around said mast. Extension at different angle may be advantageous if different draft and twist properties are desired for different directions of sailing, i.e. port tack or starboard tack.

According to an exemplary embodiment of the present invention the device further comprises at least one bearing to be arranged inside said outer tube, on one side of said intermediate tube(s). The bearing may be circular, and its purpose is to enable the outer tube to rotate around the mast and transfer horizontal forces acting on the outer tube to the inner tube and/or mast.

In one exemplary embodiment, the device may comprise two such bearings, arranged inside said outer tube on opposite sides of said intermediate tube(s). This is advantageous since it further promotes rotation of the outer tube around the mast, and forces acting on different parts of the outer tube are more evenly transferred to said mast and/or inner tube.

In another exemplary embodiment, the device comprises a third bearing, arranged between said outer tube and the top of said mast, above said inner tube. This third bearing enables transfer of vertical forces acting on the outer tube to said mast top.

According to another exemplary embodiment, the device further comprises at least one circular washer to be arranged inside said outer tube. The washer may have at least one tenon. It may be vertically locked to the inner tube, and the purpose of providing such a washer is for transferring vertical forces acting on said intermediate tube(s) to said inner tube and/or mast.

In another exemplary embodiment a washer may be horizontally locked to the inner tube, so that it can transfer horizontal forces from the outer tube to the inner tube. In yet another exemplary embodiment, two washers with stop tenons may be used for letting the user adjust the maximum angle to which the outer tube can rotate. These washers may also transfer forces from the outer tube to the washer that is horizontally locked.

According to another exemplary embodiment, the device further comprises rubber sealing for preventing dirt, water and other unwanted material from entering the device.

According to one exemplary embodiment of a device according to the first aspect of the present invention, the various tubes comprised by the device may be made of a reinforced thermoplastic material. This is advantageous since this type of material is strong enough for the purpose, yet light compared to other strong materials. The tubes may be made from the same or from different materials. Having them made from the same material makes for a simpler manufacturing process, while using different materials enables optimising the material for each of the tubes. It may be desirable that the densities of the used materials for the tubes do not exceed 1600 kg/m<3>, and more preferably are below 1400 kg/m<3>, in order to limit the weight of the device.

In another exemplary embodiment, the load-distributing parts of the device may be made from stainless steel. This is advantageous since it is a strong material.

According to one exemplary embodiment, the device is intended to be used on a windsurfing mast.

According to a second aspect of the present invention, a method for improving sail twist of a sail connected to a mast is provided, said sail having battens. The method comprises the steps of - arranging on said mast a device having at least a rotatable part and a sliding track, said rotatable part being arranged in a neutral position, - connecting at least one of said battens to said device, wherein a wind of a force below a threshold value causes the rotatable part of said device to rotate around the longitudinal axis of said mast, away from said neutral position, so that said batten moves in said sliding track. A wind of a force above said threshold value causes said rotatable part to rotate around the longitudinal axis of said mast, further away from said neutral position, so that said batten slides further in said sliding track, and at the same time is inclined in a plane extending along the height of the mast, so that the angle between the longitudinal axis of the mast and said batten is changed. This inclination lowers the tensile stress in the sail, which enables the sail to twist as desired in strong winds and speeds.

According to one exemplary embodiment, said threshold value may be a predetermined threshold value. According to another exemplary embodiment, said device further comprises spring means, and said predetermined threshold value may then be determined by determining the stiffness of said spring means.

The method may be performed using a device according to any one of the exemplary embodiments of the first aspect of the present invention. It is the angled portion(s) of the aperture(s) in the intermediate tube(s) of this first aspect which enable(s) the inclination of the batten described in this second aspect.

The step of connecting at least one of said battens may in one exemplary embodiment of the second aspect of the present invention be performed with the top batten. In another exemplary embodiment, the batten to be connected may be a batten other than the top batten. The arranging of a device on a mast may be done so that the device is permanently attached to the mast, or it may be done so that the device can be detached and rearranged.

Brief description of the drawings This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing three exemplary embodiments of the present invention.

Figure 1 is an exploded schematic view of a device according to a general embodiment of the first aspect of the present invention.

Figure 2 is a section view of a device according to a first specific embodiment of the first aspect of the present invention, arranged on a mast at the top batten of a sail.

Figure 3 is a section view of a device according to a second specific embodiment of the first aspect of the present invention, arranged on a mast at a batten other than the top batten of a sail.

Figure 4a is a perspective view of an assembled device according to the first specific embodiment of the present invention connected to a batten of a sail, when the batten is in its original position.

Figure 4b is a perspective view of an assembled device according to the first specific embodiment of the present invention connected to a batten of a sail, when the batten is inclined from its original position.

Detailed description of embodiments Figure 1 shows an exploded schematic view of a device according to a general embodiment of the first aspect of the present invention. The illustrated device comprises an inner tube 1 having a longitudinal axis L1. Outside of the inner tube 1 there is a first intermediate tube 2 and a second intermediate tube 3. The first and second intermediate tubes 2, 3 each comprise a circumferential wall 12, 13, and in each of the respective circumferential walls 12, 13 there is an aperture 22, 23. Each aperture 22, 23 comprises a straight portion 32, 33 arranged perpendicularly to the longitudinal axes L2, L3 of the intermediate tubes 2,3, an angled portion 42, 43 extending from one end of the straight portion 32, 33, here shaped as a smooth curve, and a rectangular portion 52, 53 extending from the other end of the straight portion 32, 33. The angled portion 42 of the aperture 22 in the first tube 2 overlaps with the rectangular portion 53 of the aperture 23 in the second tube 3, and the angled portion 43 of the aperture 23 in the second tube 3 overlaps with the rectangular portion 52 of the aperture 22 in the first tube 2. The straight portions 32, 33 of each of the apertures 22, 23 also overlap. This results in a common aperture 4 through both of the intermediate tubes 2, 3, from here on referred to as a sliding track 4, comprising a straight portion 14 and two angled portions 24, 34, here shaped as smooth curves.

Outside of the intermediate tubes 2,3 there is an outer tube 5 having a longitudinal axis L5 and comprising a circumferential wall 15 and two flanges 25 extending radially outwards from said circumferential wall 15. Between the two flanges 25 there is an aperture 35 in the circumferential wall. The outer tube 5 further comprises an additional aperture 45 in the circumferential wall 15, as well as a connection aperture 55 through the flanges 25.

The general embodiment further comprises a spring 6 arranged around the intermediate tubes 2, 3 and inside the outer tube 5. The spring 6 of Fig. 1 is bent into an open circular shape and held in position by four tenons (not shown) on the outermost of the intermediate tubes 2, 3. There are also two tenons (not shown) in the outer tube 5 enabling loading of the spring 6 when the outer tube 5 is rotated to a certain degree around the longitudinal axes of the intermediate tubes L2, L3.

When the device is mounted on a mast, e.g. a windsurfing mast, said inner tube 1 is adapted to be rotationally locked to said mast, so that all the forces acting on the device are transferred to the mast through said inner tube. The locking to the mast can be achieved in different ways, which will be further described in relation to the first and second specific embodiments illustrated in Figures 2 and 3.

The intermediate tubes 2, 3 are adapted to be arranged around and locked to said inner tube 1 so that the longitudinal axes L1, L2 and L3 align. The outer tube 5 is to be rotatably arranged around the inner tube 1 and the intermediate tubes 2,3, so that the longitudinal axes of all four tubes L1, L2, L3, L5 align, and so that the aperture 35 in the circumferential wall 15 of the outer tube 5 overlaps with at least a portion of the sliding track 4 of the intermediate tubes 2, 3. The additional aperture 45 in the circumferential wall 15 of the outer tube is configured for enabling mounting and adjustment of the device.

The flanges 25 of the outer tube 5 are arranged so that a batten can be put in between the flanges and connected to the outer tube 5 through a connection aperture 55. The batten should be arranged so that it extends through the aperture 35 in the outer tube 5 and into the sliding track 4 of the intermediate tubes 2, 3. This arrangement results in that when the outer tube 5 is rotated around the mast, the batten end will move along the sliding track 4. In low winds, the spring 6 is not loaded and the outer tube 5 can therefore only rotate to a certain degree. In stronger winds loading of the spring 6 enables further rotation of the outer tube 5. Two tenons (not shown) in the outer tube 5 are placed so that the outer tube 5 can rotate to a certain degree without loading the spring 6. While the spring 6 is not loaded, the batten end can only move along the straight portion 14 of the sliding track 4, which allows the sail to have a profiled draft without twist in low winds and speeds. In high speeds and strong winds, the spring 6 is loaded and the outer tube 5 can rotate further around the longitudinal axes of the intermediate tubes L2, L3. When this happens the batten end also moves along one of the angled portions 24, 34 of the sliding track 4, which causes the batten to be inclined in a plane extending along the height of the mast, so that the angle between the longitudinal axis of the mast and said batten is changed. This inclination results in a lower tensile stress in the upper portion of the sail, which enables the sail to twist as desired in high speeds and strong winds.

The length of the straight portion 14 of the sliding track 4 will affect the angle of the leading edge of the profiled draft in the front of the sail; a longer portion will give a more angled leading edge, while a shorter portion will give a less angled leading edge. The length of the straight portion 14 can be adjusted by rotating the first 2 and second 3 intermediate tubes in relation to each other, and locking them in the desired position.

Figure 2 illustrates a section view of a device according to a first specific exemplary embodiment of the present invention. The device is intended to be mounted at the top of a mast 100 and to be connected to the top batten 10 of a sail and the edge of the sail cloth 120. The device comprises an inner tube 1, two intermediate tubes 2, 3, an outer tube 5 and a spring 6 in accordance with the general exemplary embodiment illustrated in Figure 1. The first specific embodiment further comprises two circular bearings 7, 17 arranged between the inner 1 and outer 5 tubes, one 7 in the upper portion and one 17 in the lower portion. These bearings 7, 17 enable rotation of the outer tube 5 around the inner tube 1, and transfer horizontal forces acting on the outer tube 5 to the inner tube 1.

There are also two thick circular washers 8, 18 arranged between the inner 1 and outer 5 tubes, one washer 8 above the intermediate tubes 2, 3 and one washer 18 below. These washers 8, 18 are locked vertically to the inner tube 1 so that they transfer vertical forces from the intermediate tubes 2, 3 to the inner tube 1. These forces arise when the batten 10 moves in the sliding track 4 in the intermediate tubes 2, 3. To lock the washers 8, 18 to the inner tube 1 they are provided with tenons that can move in vertical tracks on the inner tube 1 as the washers 8, 18 are mounted. To lock them vertically there are horizontal tracks in the inner tube 1 in which the washers 8, 18 are rotated so that the tenons prevent the washers 8, 18 from moving in a vertical direction.

Further, the device according to the first embodiment is provided with two washers 28, 38 with radial tracks and stop tenons. These are arranged in the lower portion of the device between the inner 1 and outer 5 tubes, and define to which angle the outer tube 5 can rotate around the inner tube 1. A stop tenon (not illustrated in Figure 2) on the end of the outer tube 5 follows the rotation of the tube 5 and hits one of the stop tenons on the washers 28, 38 with radial tracks when rotated as far as possible. The purpose of these washers 28, 38 is to let the user adjust the maximum angle to which the outer tube 5 can rotate. The radial tracks are used to keep the washers 28, 38 in a horizontally locked position.

Adjacent to the washers 28, 38 with radial tracks and stop tenons there is another washer 48 with radial tracks that is locked horizontally to the inner tube 1, so that it can transfer horizontal forces from the outer tube 5 to the inner tube 1. There is also a washer 58 arranged just below one of the bearings 17, which is locked vertically to provide support for the washers 28, 38, 48 and keep them in place when a nut 68 is screwed in. This nut 68 at the end of the device holds the two washers 28, 38 with radial tracks and stop tenons, the horizontally locked washer 48 with radial track, and the vertically locked washer 58 in a locked position compared to the inner tube 1. In order to adjust the washers 28, 38 with stop tenons so that the maximum angle of rotation of the outer tube 5 is adjusted, the nut 68 has to be loosened.

The first embodiment further comprises rubber sealing 9 in various parts of the device to prevent dust, water, sand, and other small particles from entering the device and influencing its design and work properties. There is also a rubber layer 19 between the inner tube 1 and the mast 100 on which the device is mounted, to ensure a secure fit.

At the top of the device according to the first embodiment there is provided a top plate 65, sealing the inside of the outer tube 5. Below this top plate 65, inside the outer tube 5 and outside of the inner tube 1, there is an additional bearing 27 for transferring vertical forces acting on the outer tube 5 to the mast top 101. Below the extra bearing 27 there is another top plate 31, for sealing the inner tube 1. On the underside of the latter top plate 31, in the centre of the device, there are tenons 41 extending down inside the inner tube 1. These tenons 41 are arranged in corresponding tracks in the mast top 101, to rotationally lock the inner tube 1 to the mast 100. In this first embodiment of the invention there are four tenons 41 for this purpose, but this number may vary.

The first embodiment further comprises a telescopic batten end 110 to connect said top batten 10 to said sliding track 4 in said intermediate tubes 2, 3. The telescopic batten 110 end is held in place in the sliding track 4 using a washer 111 and a bolt 112. To hold the two intermediate tubes 2, 3 in their desired position in relation to each other and the rest of the device, a screw 44 is used.

A device according to a second specific exemplary embodiment of the present invention is illustrated in Figure 3. This device is intended to be mounted on a mast 100 and to be connected to the end of a batten 10’ of a sail other than the top batten, and to the edge of the sail cloth 120. This embodiment also comprises an inner tube 1, two intermediate tubes 2, 3, an outer tube 5 and a spring 6 in accordance with the general embodiment illustrated in Figure 1. The device further comprises two circular bearings 7, 17 arranged between the outer 5 and inner tube 1, similarly to the first specific embodiment illustrated in Figure 2. There are also two thick circular washers 8, 18 locked vertically, one washer 18 above the intermediate tubes and one washer 8 below, also in accordance with the first embodiment. The telescopic batten end 110, as well as the washer 111 and bolt 112 for keeping it in place in the sliding track 4 is also included in the second exemplary embodiment, as well as the screw 44 for locking the first 2 and second 3 intermediate tubes to the inner tube.

Further, the device is provided with two washers 28, 38 with radial tracks and stop tenons. These have the same purpose and work in the same way as in the first embodiment, but in this second embodiment they are arranged in the upper portion of the device instead of in the lower portion. In accordance with the first embodiment, the second embodiment also comprises a washer 48 with radial track that is locked horizontally as well as a washer 58 locked vertically, arranged adjacent to the washers 28, 38 with stop tenons. Further, in accordance with the first embodiment, there is provided a nut 68 in the second embodiment for enabling loosening and adjustment of the washers 28, 38 with stop tenons.

The second embodiment is further provided with rubber sealing 9 in several portions of the device, as well as a rubber layer 19 between the inner tube and the mast on which the device is to be mounted, also in accordance with the first embodiment.

In order to lock the inner tube 1 of the second embodiment to the mast 100, the upper and lower ends of the tube both have conical portions 11, 21 shaped so that the thickness of the circumferential wall decreases towards the ends of the tube. Two conical rings 51, 61 arranged around each of the conical portions 11, 21 of the inner tube 1 are used together with two washers 71, 81 and nuts 91, 92 for locking the tube in place.

Figure 4a illustrates the first specific embodiment of the first aspect of the present invention when in use, i.e. with a batten mounted in it. In this illustration, the batten is in its original position, i.e. a non-inclined state. This occurs when the batten is only moving along the straight portion of said sliding track in said intermediate tubes, which it does in low winds and speeds. In this state, the tensile stress in the sail prevents the top portion of the sail to twist, which is desired in low winds and speeds. In Figure 4b, the same embodiment is illustrated, but with the batten inclined. Inclination occurs when the batten is moving along one of the angled portions of the sliding track, which it can do in high winds and speeds. The batten end moving in the sliding track is elevated, and due to this and the connection between the batten and the flanges, the other end of the batten is then lowered, resulting in an inclination. This inclination lowers the tensile stress in the sail cloth so that the top portion of the sail can twist, which is desired in high winds and speeds.

The person skilled in the art realizes that the present invention by no means is limited to the embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. For example, instead of having an inner tube on which the other components are mounted, the different components may be mounted directly on a mast. Further, it is possible to have only one intermediate tube instead of two as in the described embodiments, and it would also be possible to have only one flange instead of two on the outer tube. Other mechanisms for locking the inner tube to the mast may also be possible, such as using pegs that go through the mast. The use of a telescopic batten end may be excluded so that the batten is in direct connection with the sliding track in the intermediate tubes. In that case, telescopic movement instead takes place at a roller connection between the batten and the flanges of the outer tube.

Claims

1. A device for improving sail twist, said device is intended to be connected to a mast and a batten of a sail, characterized by said device comprising - an outer tube (5) having a longitudinal axis (L5), said outer tube (5) comprising a circumferential wall (15) and an aperture (35) in said wall, - at least a first intermediate tube (2) adapted to be arranged rotationally locked to said mast, the first intermediate tube (2) comprising a circumferential wall (12), arranged at least partially inside said outer tube (5), the first intermediate tube (2) having a longitudinal axis (L2) arranged so that said longitudinal axis (L2) coincides with said longitudinal axis of said outer tube (L5), said first intermediate tube (2) further having an aperture (22) in said circumferential wall (12) comprising a straight portion (32) arranged perpendicularly to said longitudinal axis and at least one angled portion (42) extending from the straight portion (32) at an angle of between 1-90<º>, and - spring means (6) arranged around at least a part of the first intermediate tube (2) and contained at least partially inside the outer tube (5), said outer tube (5) is adapted to be rotatably arranged around said first intermediate tube (2) and arrangeable in a neutral position in which said spring means is not loaded and said aperture (35) of said outer tube (5) is aligned with at least a part of said straight portion (32) of said aperture (22) of said first intermediate tube (2), wherein said aperture (22) in the first intermediate tube (2) is adapted to be connected to a batten extending through said aperture (35) in said outer tube (5).

2. A device for improving sail twist according to claim 1, wherein said outer tube (5) is provided with at least a first flange (25) extending radially outwards from said circumferential wall (15).

3. A device for improving sail twist according to claim 2, wherein said first flange (25) has an aperture (55) to which a batten can be connected.

4. A device for improving sail twist according to any one of the preceding claims, wherein the outer tube (5) is provided with a second flange (25) extending radially outwards from said circumferential wall (15) of said outer tube (5).

5. A device for improving sail twist according to any one of the preceding claims, wherein said device further comprises an inner tube (1) arranged inside said first intermediate tube (2), said inner tube (1) having a longitudinal axis (L1) arranged to coincide with said longitudinal axes of said first intermediate (L2) and outer tubes (L5), said inner tube (1) being adapted to be arranged rotationally locked to said mast and said first intermediate tube (2).

6. A device for improving sail twist according to any one of the preceding claims, wherein said device further comprises a second intermediate tube (3) having a longitudinal axis (L3), a circumferential wall (13) and an aperture (23) in said circumferential wall (13), said aperture (23) comprising a straight portion (33) arranged perpendicularly to said longitudinal axis (L3) and at least one angled portion (43) extending from the straight portion (33) at an angle of between 1-90<º>, said second intermediate tube (3) being arranged at least partially inside or outside said first intermediate tube (2) so that said apertures (22, 23) at least partially overlap.

7. A device for improving sail twist according to claim 6, wherein said first (2) and second intermediate tubes (3) can be rotated and locked in relation to each other to adjust the overlap of their respective apertures (22, 23).

8. A method for improving sail twist of a sail connected to a mast, said sail having battens, said method comprising the steps of - arranging on said mast a device according to any one of the preceding claims, said device having at least a rotatable part and a sliding track, said rotatable part being arranged in a neutral position, - connecting at least one of said battens to said device, wherein a wind of a force below a threshold value causes the rotatable part of said device to rotate around the longitudinal axis of said mast, away from said neutral position, so that said batten moves in said sliding track, and wherein a wind of a force above said threshold value causes said rotatable part to rotate around the longitudinal axis of said mast, further away from said neutral position, so that said batten slides further in said sliding track, and at the same time is inclined in a plane extending along the height of the mast, so that the angle between the longitudinal axis of the mast and said batten is changed.