SE2230326A1 - A mast mounted rope device for boom control - Google Patents

Abstract

Summary of the invention[0042] A braking device for a sailboat boom with a mast fitting for connecting braking lines led to the boom, which almost fully eliminates the downward loads from the braking lines and enabling placement of the braking lines at a relatively close distance to the mast.[0043] The braking line movement is controlled by means of a rope friction brake. The rope friction brake efficacy is regulated by adjustments of braking line tension in the system.[0044] An optional damper can be introduced in the system for automatic regulation of braking force related to wind strength.[0045] The braking system is independent of boom vertical movement and trim.[0046] The brake can easily be trimmed for no braking and a freely moving boom to gradually increased boom braking up to an almost locked boom at any chosen horizontal position of the boom.[0047] The invention enables a new boom brake that by having the braking lines at the boom level and close to the mast, the braking lines are fully out of the deck layout and out of the deck passage area, and the device can be continuously mounted out of the way being ready for easy activation by a control line led to the cockpit.

Description

A MAST MOUNTED ROPE DEVICE FOR BOOM CONTROL Field of invention [0001] This invention concerns the control of booms on sailboats with one mast or more and booms connected to the masts for sail control.

Background of the invention

[0002] One of the most dangerous parts of a sailboat is the moving boom. When the boom is moving inwards to the centreline of the boat, for example during an accidental gybe, the boom is out of control from the sheets, and the wind pressure in the sail connected to the boom can accelerate the boom to generate tremendous forces in the freely moving boom. [0003] The forces in an uncontrolled boom can cause fatal human injuries such as severe head injuries and sweeping of crew members overboard, as well as causing damage to the sailboat rig. Furthermore, the mainsheet become very dangerous when sweeping uncontrolled over the cockpit in an unexpected gybe.

[0004] To hold the boom in place preventer lines can be rigged from the boom end to a forward part of the boat, but these solutions are unwieldy and painstaking to use.

[0005] Previous inventions for damping boom movement are so called boom brakes, that use lines led from the boom to the side decks with different forms of rope friction brakes or dampers hanging under the boom. Devices of this type are known from documents U.S. Pat. No. 4,l38,962; U.S. Pat. No. 4,94l,420; U.S. Pat. No. 5,390,6l7; U.S. Pat. No. 20090320732; GB 2 299 798 and EP 2010428.

[0006] However, these devices have several drawbacks: a) the geometry and function of the brakes necessitates lines that goes at an angle of approximately 45 degrees from the boom to the deck, resulting in lines placed on the side deck, often to be fixed at the shroud chain plates, leading to tripping hazards and unfavourable aesthetics that hampers the use of these devices; b) most of the devices' lines have to have some tension for optimal function of the brakes, which can conflict with the boom vang adjustments like a quasi-kicking strap and thereby complicating both sail trimming and brake adjustments; c) the use of most of these devices (except EP 2010428) necessitates manual adjustments of the brake related to the wind forces, which is an uncertainty factor for robust reliability of the brakes in various weather conditions; d) several devices needs to uncouple line end points for disengagement of the brake, which can be cumbersome and means loose lines to handle on deck, especially problematic if a quick release is required.

[0007] To have a more widely use of a safety product such as a boom brake it will have the requirements to be aesthetically attractive or at least have a neutral look and it should not impose additional safety risks in itself such as tripping hazards from long lines over deck walking areas. It should be very easy to adjust and release and it should be totally independent of other trim functions on the sailboat such as the vang adjustments of boom vertical trim. Furthermore, it would be a benefit with an easy trim function for having the boom locked in any selected position, for example at sail handling, in harbours with lashed sails, in a MOB situation, in light wind downwind sailing and several other situations. The present invention fulfills these mentioned requirements for a new boom brake.

[0008] The main drawback of the present state of the art boom brakes mentioned above in a), in which the relatively widely spaced fixing points for the brake lines are in conflict with safe mobility on deck and aesthetics, is related to the physical properties of a boomed sailboat rig. lf the braking lines in these devices would be placed more inboard, the traction forces in the lines during boom movements would increase substantially due to the decreased angle between brake line and boom. This will lead to large downward forces on the boom during boom braking, that can”t be counteracted by the relatively modest lifting forces in the boom end, resulting from upward drag of the mainsail. On modern sailboats with spring-loaded vangs instead of topping lifts this will lead to a dangerous lowering of the boom over the cockpit area during an accidental gybe and rendering the brake very inefficient because of a decrease in braking line movement according to the geometrical conditions of the line configuration.

Description of the invention

[0009] The present invention solves the above described problem with boom lowering during boom braking, that occurs if the braking lines fixing points are placed in close proximity to the mast, by a mast fitting that is allowing for braking lines to be led horizontally almost parallel to the boom, thereby creating very small and fully manageable downward pulling forces on the boom during braking of the boom, including the use of relatively small horizontal pulling angles (less than 45degrees) for the braking lines in relation to the boom. The mast fitting has bilateral arms extending transversely on each side of the mast, placed at or close to the height of the boom gooseneck pivotal point, with a first and a second line attachment point on each of the first and second arm of the mast fitting, preferably on the outer parts of the arms. The said mast fitting is preferably placed at the height of the boom gooseneck pivotal point or less than 3dm above or below this point. According to the invention, said line attachment points are connected to a first braking line portion and a second braking line portion attached to the boom. The first respectively second braking line portions could be attached to a first connecting point respectively a second connecting point, e.g. a connecting point on each respective lateral side of the sailboat boom, or to a common boom connecting point for both braking line portions which may be located on either the underside or the upperside of the boom, in order to brake the horizontal boom movement. According to a first embodiment of the invention, the first braking line portion and said second braking line portion forms part of the same braking line.

According to a second embodiment of the invention, the first and/or second line portion are connected to a rope friction brake.

[0010] ln comparison to conventional boom brakes in the prior art, where the braking lines for proper functionality have to go from the boom down to the deck at an angle relative to the longitudinal section of the boom of approximately 45 degrees, the present invention enables the braking lines to decrease the same angle to approximately the half, e.g. around 22,5 degrees. In addition, the braking lines will be fully out of the way from the deck layout, giving free deck passage with no obstructing braking lines. This enables the boom braking device to be continuously mounted as an intrinsic part of the rig ready for use and to be activated at any time.

[0011] To have optimal functionality the said braking line of the device has to have a uniform braking line tension throughout the full horizontal boom sweeping sector for obtaining an even braking efficacy in the rope friction brake. ln order to avoid a certain slack in the braking line that can occur when the boom is in its outward position of the sailboat boom sweeping sector as compared to when the boom is in the midships position, according to a third embodiment of the invention, there is a geometrical calculation done for each specific sailboat rig that will use the device so that the first connecting point respectively the second connecting point at the mast fitting are located at a case-specific calculated distance longitudinally behind a line perpendicular to the longitudinal direction of the boat including the boom gooseneck pivotal point at the boom-mast connecting point, to obtain a stable value on the sum of the lengths of said first braking line portion and said second braking line portion in any horizontal sailboat boom position. In this way the braking line tension will be almost unchanged during the boom horizontal movement.

[0012] The exact distance longitudinally behind the boom pivotal point for location of the connecting points at the mast fitting is calculated with the values for the distance between the two braking line connecting points at the mast fitting and the distance from these connecting points to the braking line connecting points at the boom.

[0013] The said rope friction brake which gives the braking ability of the device can be of any known type of rope friction brake and be connected to the braking line anywhere in the device.

[0014] According to a fourth embodiment of the invention, said rope friction brake is a rope friction brake placed at the mast.

[0015] According to a fifth embodiment of the invention, said rope friction brake is a rope friction brake placed on or between said first connecting point and second connecting point at the mast fitting.

[0016] According to a sixth embodiment of the invention said rope friction brake is a rope friction brake in the form of a cylindrical fitting with caps on the ends giving lids extending one or more rope diameters outside of the cylinder radius. The said braking line is led over the cylinder in a chosen number of turns giving friction to the system.

[0017] The tension in the first and second braking lines, and thereby the level of friction created in the rope friction brake will decide the braking efficacy of the device. According to a seventh embodiment of the invention, the level of friction created in the rope friction brake is controlled by a separate control line, which enables adjustments of the braking efficacy. The separate control line could for example control a braking line tension mechanism which consists of the braking line led through freely moving blocks and tackle.

[0018] The inventions braking lines are as mentioned led almost horizontally in relation to the boom and the braking line connecting points at the mast fitting are placed close to the boom gooseneck pivoting point, which will make adjustments in braking line tension fully independent on boom vertical trim, enabling a large range of line tension settings including a very hard tightening of the braking lines.

[0019] Most prior art rope boom brakes have some inherent friction in the rope friction brake even with slack in the lines and the only way to fully disengage these brakes when sailing is to uncouple the lines from their fixing points on the deck or superstructure, giving long loose lines dangling on deck. The inventions braking line tension mechanism for adjustment of braking efficacy is characterized by two advantageous properties of the invention. Firstly, the possibility to tighten the braking lines very tight without affecting the boom vertical trim, which allows for the use of cylindric rope friction brakes giving very low line friction when there is slack in the braking line, but giving high line friction with high braking line tension. Secondly, the fact that the different parts of the braking lines forms part of the same braking line between the connecting points at the mast fitting, giving a continuous line without endpoints in this part of the device. Together, this enables a system for coupling or uncoupling of the braking device in an easy way by a small adjustment in the control line, without involving long loose lines on the deck. This furthermore adds to the usefulness of the boom braking device, which can be continuously mounted as an intrinsic part of the rig ready for use and to be activated at any time.

[0020] When sailing with a boom brake based on a rope friction brake there is a need for manual adjustments of the line tension to adapt the boom brake to various wind conditions for obtaining the desired horizontal boom speed. According to an eighth embodiment of the invention said boom braking device includes a damper, e.g. a rotary viscous damper, connected to the braking line anywhere in the device for automatic adjustment of damping forces and boom speed related to the various sail forces on the boom in different wind conditions. The rotary viscous damper is connected to the system by a sling in said braking line led over a pulley wheel within a low-friction groove with the braking line held in place at the pulley wheel by two small diameter sheaves.

[0021] For example, the rotary viscous damper may be placed at the low load side of a rope friction brake that is placed at the mast, where the viscous damper and the line tension mechanism is forming a single unit mounted on a sliding car connected to the line tension control line, enabling both damping of braking line movement and regulated line friction in the device for adjustment of boom braking, including a high braking line tension that almost block the boom.

[0022] A desired property of the invention is that the boom brake can be easily disengaged, enabling a freely moving boom, and that the brake can be as easily engaged. The control line for the line tension in the brake fulfil this mission. The optional damper in the device could also be provided with means for engaging and disengaging the damper in the device and the viscous damper could be arranged to be manually or semi-automatically engaged. According to a ninth embodiment of the invention the rotary viscous damper housing is freely moving together with the pulley wheel when the brake is disengaged. A spring-loaded pivoting pin is fitting into pin holes in the viscous damper housing, which is used to fix the damper housing to the superstructure, thereby engaging the viscous damper to damp the said braking lines movement in the pulley wheel.

[0023] According to a tenth embodiment of the invention the spring-loaded pivoting pin is connected to the said control line for braking line tension in such a way that a slack in the control line have the pin in the out position forced by spring loads, Whereas some tension in the control line allow the pin to glide into a pin hole in the housing for engaging the viscous damper. The connection between the control line and spring-loaded pin is by means of a chock cord or spring, enabling the control line to be further tensioned for braking line tension when the spring-loaded pin is firmly engaged. The mechanism is terrned semi-automatic in that the damper will be activated at the same time as the control line is pulled to increase line tension and activate the line braking mechanism.

[0024] According to an eleventh embodiment of the invention the engagement of the viscous damper in said unit mounted on a sliding car connected to the line tension control line is obtained by a spring-loaded pin that is gliding into the damper housing pin hole when the control line is tensioned and pulling the sliding car. Any tension in the control line will engage the pin in the pin hole, and the pin will be released when there is slack in the line and the sliding car is springing back from elasticity in the braking lines. The mechanism is termed semi-automatic in that the damper will be activated at the same time as there will be tension in the braking line.

[0025] According to a twelfth embodiment of the invention the spring-loaded pin is manually controlled by a separate control line, separated from the braking line tension control line, acting directly on the spring-loaded pin to engage or disengage the pin.

[0026] A damper included in the device can be in the form of a linear damper. According to a thirteenth embodiment of the invention a linear viscous or pneumatic damper can be placed for automatic adjustment of damping force related to various boom forces in different wind conditions. The linear damper is connected to the braking line system by a link between the damper piston rod and the braking line.

[0027] It goes without saying, the invention is not restricted to the embodiment of this braking device that has been described hereinabove by way of examples but on contrary encompasses all variants thereof.

Drawing ñgures Figure 1. Principles of mast fitting With running ropes Figure 2. Mast fitting seen from above With line connecting points behind the gooseneck pivotal point Figure 3. Mast fitting With fairleads and separate rope friction cylinder on the mast Figure 4. Mast fitting With optional rotary viscous damper on the mast Figure 5. Rotary viscous damper housing, detail of activation mechanism Drawing reference numerals 1. Boom 2. Mast 3. Mast fitting With transversal anns 3a. First arm 3b. Second arm 4. Braking line 4a. First braking line portion 4b. Second braking line portion . Boom connecting points for braking line 5a. First boom connecting point 5b. Second boom connecting point 6. Mast fitting outer parts With line attachment points 6a. First line attachment point 6b. Second line attachment point 7. Block 8. Control line 9. Boom gooseneck pivotal point 10a. The dotted line indicates the specific calculated distance between the boom gooseneck pivotal point and the transverse marking line (lOb) to give the correct position for the fairlead/friction cylinders on the mast fitting l0b. Dashed line showing correct athwartships position for fairlead/friction cylinders. ll. Cylinder functioning as fairlead 12. Mast mounted rope friction cylinder 13. Rotary viscous damper unit on gliding car on a track (consisting of parts 14-19) 14. Cover . Rotary viscous damper 16. Pulley Wheel 17. Low-friction bearing 18. Sliding car With mounting plate for rotary viscous damper unit, With rope feeders 19. Mast mounted track for sliding car . Rotary viscous damper pin hole 21. Spring 22. Spring-loaded pivoting pin 23. Boom braking device Detailed description of drawings

[0028] In FIG. 1 is disclosed an embodiment of a boom braking device 23 for braking the movement of a boom 1. The boom braking device comprises a mast fitting 3, including a first ann 3a With a first line attachment point 6a and a second ann 3b With a second line attachment point 6b, attached to the mast 2. As can be seen in FIG. 1, the mast fitting 3 is positioned at the height of the boom gooseneck pivotal point 9. A first braking line portion 4a and a second braking line portion 4b forming part of a braking line 4 are attached to a first boom connecting point Sa respectively a second boom connecting point Sb, and running from the boom 2 to be connected to the first line attachment point 6a respectively the second line attachment point 6b of the mast fitting 3 in a sector horizontally almost parallel to the boom, thereby creating very small and fully manageable doWnWard pulling forces on the boom during braking of the boom. The arrangement in FIG. 1 thus solves the above described problem With boom loWering during boom braking, that Will occur if first and second line attachment points 6a, 6b are placed in relatively close proximity to the mast below the boom gooseneck pivotal point. The mast fitting 3 for the braking line portions 4a, 4b in this embodiment is preferably positioned exactly at the height of, or less than 3 dm above or below, the boom gooseneck pivotal point 9 in order to reduce doWnWards pulling forces. [0029] The first braking line portion 4a is led from the first boom connecting point Sa on one side of the boom 2 to the first line attachment point 6a located on an outer part of the first arm 3a on the same side of the mast fitting 3, Where the rope is led in tums around a friction cylinder (placed at 6a) and further led through a fairlead and a freely moving block 7 at the mast, and the line continues by a fairlead to the second line attachment point 6b located on an outer part of the second arm 3b on the opposite side of the mast fitting 3, Where it is led in turns around a friction cylinder (placed at 6b) and back on the opposite side of the boom 2 Where the end of the second braking line portion 4b is attached at the second boom connecting point Sb.

[0030] By pulling the block 7 With a control line 8, there Will be an increased tension in the running braking line that is increasing the rope friction on the friction cylinders, Which Will result in braking of the horizontal movements of the boom.

[0031] By adjusting the tension in the control line 8 a variable braking efficacy can be obtained. A very hard tensioning in the control line Will almost block the boom, Which can be very useful to stabilize the boom during doWnWind sailing in light Winds and choppy Waters, When the boom tends to slam against the stays. Furthermore, it is very easy to uncouple the braking system just by releasing the control line 8, Which Will render a freely moving boom Without long loose rope ends dangling around on deck, a problem found in many conventional rope boom brakes.

[0032] As shoWn in FIG. 2 the first and second line attachments points 6a, 6b for the braking line portions 4a, 4b onto the outer part of the amis 3a, 3b of the mast fittings 3 are placed at a certain athWartships distance aft of the boom pivotal point 9, to give a continuous running line tension throughout the full range of horizontal motion of the boom. The exact athWartships distance is calculated geometrically from rig data on the distance betWeen the first line attachment point 6a and the second line attachment point 6b, and the distance betWeen the boom gooseneck pivotal point 9 and the first and second boom connecting points Sa, Sb. The resultant calculated distance athWartships of the boom gooseneck pivotal point and the first and second braking line attachment points 6a, 6b (laying on the transverse dashed line 10b) is represented by the dotted line 10a.

[0033] Since the running braking liiie portions 4a, 4b going from the boom connecting points Sa, Sb are connected to the mast fitting 3 at the height of the boom pivotal point 9, as seen in FIG. 1, the braking line 4 Will be constantly tensioned independent of the boom vertical trim in any horizontal boom position, which make the boom brake independent of adjustments in kicking strap vertical trim of the boom. Importantly, a high tension in the braking line will not affect the kicking strap vertical trim of the boom. This is eliminating the well-known problem with conventional rope boom brakes that interferes with boom vertical trim. Together, the athwart position of the first and second line attachment points 6a, 6b on the mast fitting 3, showed in FIG. 2, and the said positioning of the mast fitting 3 at the height of the gooseneck 9, will render a possibility to tighten the control line 8 very hard without affecting the boom trim level in any way. This enables a possibility to almost lock the boom in any position, which is an advantageous feature of the invention.

[0034] A single rope friction cylinder 12 can be placed at the mast, as seen in FIG. 3, as an alternative to the use of the said friction cylinders placed at the outer parts of the arms 3a and 3b of the mast fitting 3. The braking line 4 will be led in turns over the cylinder 12 to give friction to the system and the braking line is further led in a sling to a freely moving block 7 for line tensioning by a control line 8. The cylindric parts of the outer mast fitting 6a and 6b will in this configuration not have turns of braking line, and will not work to give rope friction, but will act as fairleads 11 for braking line feeding onto the rope friction cylinder 12 placed at the mast.

[0035] Any type of rope friction brake can be used with the described mast fitting 3, and a friction brake can alternatively be placed at or under the boom with the ends of the braking line portions 4a, 4b attached to the braking line attachment points 6a, 6b at the outer parts of the arms 321, 3b of the mast fitting, and the braking line running through the friction brake placed under the boom at a distance from the boom pivotal point corresponding to the boom connecting points 5a, 5b. However, the described placement of friction brakes in FIGS. 1 and 2, at the mast fitting or at the mast respectively, are advantageous since there are no freely moving brake parts dangling around under the boom, such as seen in many conventional boom brakes.

[0036] As an option for an automated braking system a rotary viscous damper 15 can be introduced to the system, as shown in FIG. 4. The rotary damper will increase its damping efficacy on the running lines if boom speed increases, thereby eliminating the need for manual adjustments of the control line in different wind conditions.

[0037] The rotary viscous damper 15 is coupled to a high-friction groove pulley wheel 16 and the braking line 4 is led in a sling over the pulley wheel, as seen in FIG. 4. In the examples given in the FIGS. 4 and 5 are shown one type of commercially available rotary damper (Enidine-VSG), but any type of continuous rotary viscous damper can be used in the device.

[0038] The damping force obtained can be varied related to rig size by using different damper sizes, and several dampers can be coupled in parallel for increased damping forces. [0039] The rotary viscous damper 15 can be placed, as shown in FIG. 4, in connection with the rope friction brake 12 that is placed at the mast, having a sling in said braking line 4 going over the pulley wheel 16. The rotary viscous dampers inner damping part is fixed to the pulley wheel. The pulley wheel and the inner damping part are connected with a low-friction bearing 17 to a solid rod mounted on a sliding car 18 on a track 19, mounted with all said parts as a single unit in a common rotary viscous damper unit 13 at the mast. Tension in the control line 8 pulls the damper unit and connected braking line downwards, giving increased braking line tension on the friction cylinder and thereby increased braking efficacy in the device.

[0040] As shown in FIG. 5, the rotary damper mounted on the sliding car 18 can have a mechanism for engagement of the damper by a spring-loaded pin 22 fitting into a pinhole 20 in the housing of the damper 15. When the control line 8 for braking line tension adjustments is tightened the sliding car with damper and connected sling of the braking line is moved downwards (upper arrow indicates sliding car movement) to place the spring-loaded pin 22 into the damper housing pinhole 20, and the damping function is engaged. With further tensioning of the control line to adjust braking line friction in the device, the spring-loaded pin will move further downward, still being in the pinhole and still locking the damper housing (lower arrow indicate spring-loaded pin movement).

[0041] The above description depicts various configurations of the boom braking device. It is of course possible to use any other altemative configuration of the ingoing parts of the invention.

Claims (11)

Claims

1. A boom braking device (23) for sailboat boom control consisting of a mast fitting (3) comprising a first arm (3a) and a second arm (3b) extending transversely on each side of the mast (2), said mast fitting being arranged on the mast at or close to the height of the boom gooseneck pivotal point (9), with a first line attachment point (6a) and a second line attachment point (6b) on each of the first and second arms (3 a, 3b) of the mast fitting (3), characterized in that said first line attachment point (6a) is connected to a first braking line portion (4a) and said second line attachment point (6b) is connected to a second braking line portion (4b) Whereby each of said first braking line portion (4a) and second braking line portion (4b) are attached to a boom connecting point (5a, Sb) on the sailboat boom (l), in order to brake the horizontal boom movement.

2. A boom braking device according to claim l characterized in that said first braking line portion (4a) is attached to the boom (2) at a first boom connecting point (Sa) on a first lateral side of the sailboat boom (l) and the second braking line portion (4b) is attached to the boom at a second boom connecting point (5b) on a second lateral side of the sailboat boom (1) such that the first and second braking line portions (4a, 4b) are arranged on a respective lateral side of the sailboat boom (l).

3. A boom braking device according to claim 1 or 2 characterized in that said first braking line portion (4a) and said second braking line portion (4b) forms part of the same braking line (4).

4. A boom braking device according to any previous claim characterized in that said first and/or second line portion are connected to a rope friction brake.

5. A boom braking device according to claim 4 characterized in that said rope friction brake is a rope friction brake (12) placed at the mast (2).

6. A boom braking device according to claim 4 characterized in that said rope friction brake is a rope friction brake placed on or between said first connecting point (6a) and second connecting point (6b) at the mast fitting (3).

7. A boom braking device according to any of claims 4 to 6 characterized in that the tension in the first and second braking lines, and thereby the level of friction created in the rope friction brake is controlled by a separate control line (8), Which enables adjustments of the boom braking efficacy.

8. A boom braking device according to any previous claim characterized in that the first connecting point (6a) respectively the second connecting point (6b) at the mast fitting are located at a case-specific calculated distance longitudinally behind a line perpendicular to the longitudinal direction of the boat including the boom gooseneck pivotal point (9) at the boom- mast connecting point, to obtain a stable value on the sum of the lengths of said first braking line portion (4a) and said second braking line portion (4b) in any horizontal sailboat boom position.

9. A boom braking device according to any previous claim characterized in that said boom braking device includes a damper, e.g. a rotary viscous damper.

10. A boom braking device according to claim 9 characterized in that said viscous damper is arranged to be manually or semi automatically engaged.

11. A boom braking device according to any claims l-8 characterized in that said boom braking device includes a linear viscous or pneumatic damper.