Device for reducing the rotation speed of the boom of a mainsail during gybing

Abstract

 A device for reducing the rotation speed of the boom (5) of a mainsail (3) mounted on the mast (4) of a sailing vessel (1) during gybing of the sailing vessel comprises damping means connected to the boom (5) of the mainsail (3). The damping means comprises a rotation damper (2) connected between the boom (5) and a fixed part of the sailing vessel (1).
A very compact device is obtained as a result of these measures, which prevents the consequences of uncontrolled gybing, while the number of external components is also small.
The rotation damper (2) is preferably placed in the vicinity of the mast (4) of the mainsail (3). The housing (7) of the rotation damper (2) is connected fixedly to the hull of the vessel (1). The arm (9) of the rotation damper (2) is connected to the boom (5) of the mainsail (3). Due to this placing close to the two parts to which the rotation damper (2) must be connected, only a small number of components is necessary for the purpose of connection.

Description

[0001] The present invention relates to a device for reducing the rotation speed of the boom of a mainsail mounted on the mast during gybing on a sailing vessel.

[0002] When a sailing vessel is sailing downwind, i.e. the situation in which the wind direction coincides, or almost coincides, with the direction of movement of the sailing vessel, the mainsail will extend wholly to port (to the left relative to the sailing direction) or to starboard (to the right relative to the sailing direction). This is to make maximum use of the thrust of the wind. The rotation movement of the mainsail, with the boom on which the mainsail is mounted, from the position extending wholly to starboard to the position extending wholly to port, and vice versa, is known as "gybing". This manoeuvre is shown schematically in figure 1.

[0003] While the position and the rotation movement of the boom with mainsail can be controlled on any other course by the crew of the vessel by means of bringing in or easing the main sheet, this is hardly possible, or at least very difficult, during gybing. An experienced sailor can perform a controlled gybe at a lower wind speed, but at higher wind speeds this is not possible because the speed of the rotation movement of the boom can then not be sufficiently controlled with the main sheet (line with pulley system with which the crew controls the position and rotation movement of the boom).

[0004] In a downwind course a gybe can moreover occur suddenly, even when there is an unintended, small change in this course (for instance due to current or high waves) and when the wind direction changes (the wind veers or backs). In these cases there is no control at all of the rotation movement of the boom, and the boom hereby swings from starboard to port, or vice versa, at very high speed and force. In such cases this is referred to as a "wild gybe".

[0005] A wild gybe often causes damage to the vessel and there is a very real danger of a vessel then capsizing or of people standing in the cockpit of the vessel being injured or thrown overboard by the boom unexpectedly swinging at high speed.

[0006] For this reason not a gybe but a so-called "storm turn" is opted for at higher wind speeds. A storm turn is made by turning the bow of the vessel to and through the wind and then running before the wind in the new course. (In technical jargon "luffing, tacking and bearing away again"). A manoeuvre known as a storm turn does however take up a lot of time and space so that it is not always possible or desirable.

[0007] In order to prevent the consequences of a wild gybe it is known to use a so-called preventer line. This is a line between the foreship and the point of the boom furthest removed from the mast. Such a line thus prevents the occurrence of gybe since the sail is prevented from moving rearward to its neutral position. The sudden occurrence of a gybe is hereby prevented, but controlled gybing is also prevented. In order to carry out desired gybing the preventer line must first be released, whereafter a wild gybe can still occur.

[0008] A device is known from US-A-5 967 073 for reducing the speed of the boom of a mainsail during gybing on a sailing vessel, comprising damping means connected to the boom of the mainsail.

[0009] The damping means are herein formed by an assembly of linear hydraulic cylinders which are coupled by means of a rack transmission to a shaft which extends parallel to the mast and which is connected to the boom of the mainsail. Because this device is relatively voluminous, it is proposed in the patent to arrange it below deck. Space is also limited under the deck of a sailing vessel, in particular close to the mast. The device is moreover expensive because of its many components.

[0010] The object of the present invention is to provide such a device which takes up less space and which can be manufactured at lower cost.

[0011] This object is achieved with such a device, wherein the damping means comprise a rotation damper, wherein the rotation damper is connected between a fixed part of the sailing vessel and the boom.

[0012] A very compact device is obtained as a result of these measures, while the number of external components is also small. The cost price is hereby low.

[0013] These advantages are enhanced when the rotation damper is provided with an arm, wherein the rotation movement of the arm relative to the housing of the rotation damper is subjected to damping.

[0014] According to a first preferred embodiment, the rotation damper is placed in the vicinity of the mast of the mainsail, the housing of the rotation damper is connected fixedly to the hull of the vessel, and the arm of the rotation damper is connected to the boom of the mainsail.

[0015] Due to this placing close to the two parts to which the rotation damper must be connected, only a small number of components is necessary for the purpose of connection. This also has the effect of reducing the cost price. Furthermore, hardly any walking space and head room is lost due to such a device.

[0016] Yet another embodiment provides the measure that the housing of the rotation damper is placed behind the mast in the direction of the vessel.

[0017] This placing disrupts the operations to be performed on a sailing vessel as little as possible and has the result that a free swing can be made at the correct moment.

[0018] A still further limitation of the space taken up by the device and of the number of necessary components is achieved when the housing of the rotation damper is integrated into the mast of the mainsail.

[0019] In order to facilitate mounting of the device according to the invention on a sailing vessel, it is attractive when the rotation damper is provided with a flange placed on its shaft and when the arm is connected to the flange by means of coupling means. It is hereby possible to initially place the housing of the device and then connect the arm to the boom and to the flange. A flange, when adapted for this purpose, moreover provides the option of connecting the arm at different angles to the flange.

[0020] The rotation damper is preferably formed by a hydraulic rotation damper. The advantages of hydraulic dampers, such as a small volume and good controllability, are hereby obtained.

[0021] According to yet another preferred embodiment, the rotation damper has a speed-dependent characteristic. Because the damper is used particularly to prevent wild gybes, this speed-dependent damping is advantageous. The damping is then adjusted such that the greatest damping is achieved at higher speeds, which are after all the most dangerous. At lower speeds a smaller damping is active so that gybing can be carried out in the normal manner.

[0022] Another preferred embodiment provides the measure that the characteristic of the rotation damper is adjustable. It hereby becomes possible to adjust the damping to the situation, which can be particularly attractive in competitive sailing. This embodiment moreover makes it possible on each occasion to adjust the start and the extent of the braking action in simple manner in accordance with the size of the sail (the thrust) which will be carried, while it is also possible with this system to regulate in simple manner the unrestrained rotation movement (the free swing) of the sail desired during tacking.

[0023] The rotation damper preferably has a free swing to allow the mainsail to move in normal situations. Being able to adjust the free swing is also attractive, for instance in sailing competitions.

[0024] Both the adjustability of the free swing and of the damping are preferably remotely adjustable. It hereby becomes possible to control these parameters, for instance from the rudder.

[0025] Yet another preferred embodiment provides the measure that the device comprises a pressure sensor which is adapted to give a warning signal when a predetermined pressure is exceeded.

[0026] The warning signal can be formed by a sound signal, a light signal or a combination thereof. The warning signal is a signal that a gybe is about to take place. The alerted persons can seek a safe position after the signal.

[0027] The invention can be applied in sailing vessels to be newly built, but it can also be applied in already existing sailing vessels. For this latter situation the invention provides a kit of parts for arranging on a sailing vessel a device according to any of the foregoing claims, characterized by a rotation damper provided with an arm.

[0028] The advantages of the remaining sub-claims will become apparent from the description.

[0029] The present invention will be elucidated hereinbelow on the basis of the accompanying drawings, in which:

Fig.1 is a schematic top view of a sailing vessel when a gybe is being carried out;

Fig.2 is a schematic side view of a first embodiment of a device according to the invention;

Fig.3 is a schematic side view of a second embodiment of a device according to the invention;

Fig.4A is a schematic cross-sectional view of a cylindrical damper according to the invention;

Fig.4B is a schematic cross-sectional view along line IV-IV in figure 4A;

Fig.5A is a schematic cross-sectional view of an alternative embodiment of a cylindrical damper according to the invention; and

Fig.5B is a schematic cross-sectional view along line V-V in figure 5A.

[0030] A first embodiment of the invention is shown in figure 2. This comprises a rotation damper 2 which serves to damp the rotation movement of mainsail 3 of a sailing vessel 1 around mast 4 of sailing vessel 1. The mainsail is connected on its underside to a boom 5, which is rotatably connected to mast 4 by means of a gaff 6 or other pivoting connection. The rotation movements of sail 3 thus correspond with the rotation movements of boom 5.

[0031] Rotation damper 2 comprises a cylindrical housing 7 which is fixedly connected to mast 4, for instance by means of brackets 8. Accommodated in cylindrical housing 7 is a hydraulic damper which damps the rotation of the flange about the vertical axis. The rotation damper also comprises an arm 9 which is connected by means of a hinge 11 to a flange 10 of cylindrical housing 7. Hinge 11 allows a rotation about a horizontal axis between flange 10 and arm 9.

[0032] Arranged on boom 5 is a bracket 12 which is connected to arm 9 on its underside by means of a ball hinge 13. The length of arm 9 can be varied by means of an extending mechanism accommodated in the arm. This mechanism is necessary to compensate the differences in length in the distance between the axis of housing 7 and bracket 12 during rotation of boom 5; after all, the points of rotation do not coincide.

[0033] This problem can otherwise also be solved by using a line between bracket 13 and the distal end of arm 9. This obviates the necessity of applying an arm 9 with a variable length. The use of this line has a further advantage, namely the fact that the rotation of boom 5 and the damper arm 9 are less strongly coupled in the vicinity of the neutral position (in which the boom extends parallel to the direction of movement of the vessel). In other words, the boom can rotate freely through a certain swing in the vicinity of this central position without the damper carrying out its damping function. Use is made of this property during tacking. Damping is after all not required during tacking. This free swing will of course also occur during gybing, although the angle of rotation of the gybing movement is generally greater than that of tacking, so that the line has already been pulled taut during an earlier part of the rotation path and the damping effect is maintained here, also during the part-path in the vicinity of the neutral position.

[0034] It will be apparent that when the boom rotates around the mast, for instance during a gybe, the rotation movement is transferred to the arm, and thereby to the rotation damper. The rotation movement of the sail and the boom is hereby damped.

[0035] Figure 3 shows a second embodiment of the device according to the invention, which differs from the first embodiment on the following points:

• Instead of being placed behind the mast in the direction of movement of the vessel, the rotation damper is placed in the mast. This is possible in the presently much-applied hollow masts manufactured from plastic, aluminium or other metals. At the position of the arm an opening must be arranged in the mast, which results in an irreversible weakening of the mast. Measures will therefore usually have to be taken to strengthen the mast around the opening.
• Instead of a circular cylindrical housing of the foregoing embodiment, a housing is applied which has the shape of a cylinder with a sector of a circle as a base.
• Instead of a coupling between boom and arm by means of a lever, as in the foregoing embodiment, the arm is connected to the boom with a rigid connection or coupled to a connecting element which is connected slidably to the boom. The compensation for the fact that the rotation points of arm and boom do not coincide is provided automatically here by displacement of the connecting element along the boom. In this embodiment the above described advantage of a reduced damping during tacking also occurs due to the degree of filling of liquid in the cylinder

[0036] It is pointed out that, as a result of the fact that the rotation points of boom and damping cylinder coincide, no compensation for the length of the arm of the damping cylinder need in principle be provided in the above embodiment. This provides the option of building the arm of the damping cylinder into the boom. However, a rotation point must then usually be provided for the movement in the vertical plane of the boom. This is however possible in principle.

[0037] According to another embodiment, the boom can be mounted directly on the shaft of the damping cylinder. The arm and the gaff are then omitted.

[0038] The diverse measures of both embodiments can also be combined.

[0039] Figures 4A and 4B show a hydraulic damper with a housing 7 in the form of a straight circular cylinder. In housing 7 is arranged a shaft 15 which coincides with the axis of the housing. Shaft 15 is mounted in the housing by means of bearings 16. On its top side the shaft is connected to a flange 10 to which is fixed a bracket 18. Bracket 18 is connected to the flange by means of a screw connection 19. In bracket 19 the arm 9 is mounted rotatably around a horizontal axis 21.

[0040] Inside the housing the shaft 15 is connected to a rotor 20. Rotor 20 extends from shaft 15 to the internal cylinder wall. Arranged in housing 7 is a wall 21 which extends as far as shaft 15. An opening 22 is arranged in wall 21. A damping action is achieved when the thus formed configuration is filled with oil. This damping action can be adjusted by adjusting the size of the openings, choosing a liquid with a modified viscosity, only partially filling the housing with oil or by taking other measures which are usual in hydraulic dampers, in particular hydraulic rotation dampers.

[0041] It is also attractive here to make a number of variables controllable, for instance by using openings with a controllable passage.

[0042] In the embodiment shown in figures 5A and 5B a housing is used having the form of a cylinder with a base in the shape of a sector of a circle. Because the maximal rotation stroke of the arm will in many cases be smaller than 180°, this is a space-saving solution. It is however not possible here to make use of a radially extending wall with an opening for controlled guiding of the liquid; in this embodiment use is made instead of a space 22 which is arranged under the main reservoir and which is connected by means of openings 23 to the chambers on either side of the rotor connected to the shaft.

[0043] It will be apparent that other constructions can be applied instead of the embodiment shown here, and that the shown embodiments can be varied. It is thus possible for instance to apply a single channel to mutually connect the chambers on either side of the rotor in controlled manner.

[0044] As already stated above, it is attractive to make use of remotely controllable damping means. It is herein possible to make use of control by means of a galvanic connection or by means of a wireless connection. The techniques which can be used for this purpose are generally known. It is hereby possible for instance to control a motor, whereby the passage of an opening in a connection between the chambers on either side of the rotor is adjusted. Other variables of the damper can also be adjusted, such as the free swing or the characteristic.

Claims

1. Device for reducing the rotation speed of the boom of the mainsail mounted on the mast of a sailing vessel during gybing on the sailing vessel, comprising damping means connected to the boom of the mainsail, characterized in that the damping means comprise a rotation damper connected between the boom and a fixed part of the sailing vessel.

2. Device as claimed in claim 1, characterized in that the rotation damper is provided with an arm, wherein the rotation movement of the arm relative to the housing of the rotation damper is subjected to damping.

3. Device as claimed in claim 2, characterized in that the rotation damper is placed in the vicinity of the mast of the mainsail, the housing of the rotation damper is connected fixedly to the hull of the vessel, and that the arm of the rotation damper is connected to the boom of the mainsail.

4. Device as claimed in claim 3, characterized in that the housing of the rotation damper is placed behind the mast in the sailing direction of the sailing vessel.

5. Device as claimed in claim 3, characterized in that the housing of the rotation damper is integrated into the mast of the mainsail.

6. Device as claimed in any of the foregoing claims, characterized in that the rotation damper is provided with a flange placed on its shaft, and that the arm is connected to the flange by means of a releasable connection.

7. Device as claimed in any of the foregoing claims, characterized in that the rotation damper is a hydraulic rotation damper.

8. Device as claimed in claim 7, characterized in that the rotation damper has a speed-dependent characteristic.

9. Device as claimed in claim 7 or 8, characterized in that the characteristic of the rotation damper is adjustable.

10. Device as claimed in any of the foregoing claims, characterized in that the rotation damper has a free swing.

11. Device as claimed in claim 10, characterized in that the free swing of the rotation damper is adjustable.

12. Device as claimed in claim 9 or 11, characterized in that the adjustability is remotely controllable.

13. Device as claimed in any of the claims 7-12, characterized in that the housing of the hydraulic damper is circular cylindrical, that the shaft of the damper connected to the coupling means is arranged in the centre of the cylinder and that a rotor of the damper is connected fixedly to the shaft.

14. Device as claimed in any of the claims 7-12, characterized in that the housing of the hydraulic damper takes the form of a cylinder with a segment of a circle as base, that the shaft of the damper connected to the coupling means extends in the centre of the circle and that the piston is connected to the shaft.

15. Device as claimed in claim 13 or 14, characterized in that a bypass is arranged in the housing and mutually connects the two chambers situated on either side of the piston.

16. Device as claimed in any of the claims 7-15, characterized in that the device comprises a pressure sensor which is adapted to give a warning signal when a predetermined pressure is exceeded.

17. Kit of parts for arranging on a sailing vessel a device as claimed in any of the foregoing claims, characterized by a rotation damper provided with an arm.

Drawing