Field of the Invention

The present invention concerns a safety release system, device and method particularly for use with sails on sailing vessels such as yachts where it can release a sail of the vessel when the sail is overloaded to minimise the risk of damage such as de-masting or damaging the rig or risk of capsizing of the vessel. The release mechanism may however have other applications such as in the towing of boats. Background of the Invention

In sailing a key aspect to control of the sail is the setting of the sail's angle relative to the wind direction and this is generally done by a control line/ rope known to yachtsmen as the "sheet". The sheet is attached directly or indirectly to the sail at one end and at the other end it normally passes through an adjustable anchoring device, e.g. a cleat or winch that is mounted on the vessel's deck, whereby the sheet may be pulled in to a short length and held or paid out farther to adjust the sail angle to suit the wind direction to trap the wind, harnessing the energy of the wind pressure on the sail into powering the vessel's travel.

As all keen yachtsmen and women know, the vessel is vulnerable in extreme stormy conditions or in more generally mild weather conditions if a sudden gust of high speed wind hits the restrained mainsail substantially full on while the sail is not trimmed to compensate. If the crew is unable to respond in time by releasing the sheet and heading to wind or otherwise trimming the sail, the wind pressure loading applied to the tethered sail (and hence mast) can exceed the safe loading threshold and can cause the yacht to keel over or the mast to snap. Also there is the possibility of accidental gybing when the wind is behind the sail and if it should shift around and cause the sail to be propelled across the boat with considerable force. This can cause considerable damage to the rigging. These hazards are integral to yachting seamanship for many. It is a major part of the yachting experience and for some the peril and need for alertness and pre-emptive or fast remedial action in adjusting the sail position or state of opening contributes greatly to the challenge and thrill of yachting. Nevertheless, for many yachtsmen a safety mechanism to reduce these risks would be highly desirable. As yet, there are, to the best of the applicant's knowledge, no effective safety systems to address the problem and there remains a need for a simple, low cost solution to the problem. Although the solution is primarily aimed at the sailing of boats it may also be useful in other activities such as for example the towing of boats.

Summary of the Invention In one embodiment the invention therefore provides a release system comprising a link within a line under load wherein the link comprises a single component that will break when the loan on the line exceeds a predetermined threshold level and wherein the breaking of the single component releases a further component that permits extension of the line.

In a preferred embodiment the line under load is the line connecting the sail of a sailing vessel to the vessel. The line may connect the mainsail to the boat, alternatively it may be the kicking strap (or vang) or it may be the line connecting the genoa or jib to the boat. In another embodiment the line may connect the mast to the boat. A release system of the present invention may be provided as a link in any one or more of these lines.

The link may be of any suitable material providing it breaks instantaneously when the load on the line exceeds a predetermined threshold. It is preferred that the link be based on a mechanical fuse such as a piece of stainless steel and it is preferably rigid. Alternatively the link may be a clutched ratchet or a hydraulic cylinder provided with a release valve that is activated when the load on the link reaches a predetermined threshold.

According to a preferred embodiment of the present invention there is provided a sail safety release system to be used on sailing vessels such as yachts to release a sail of the vessel from initial restraint when the sail is overloaded, the system comprising a link between the sail at one end and at the other end a control line leading back to the boat for restraining the sail, wherein the link is configured to act as a mechanical fuse that is rigid and will break apart releasing the control line's initial restraint on the sail when the load applied to the sail and pulling on the control line exceeds a predetermined safe threshold level.

For the majority of applications of the system the control line in question is the main sheet for control of the main-sail. However, the control line may instead be for control of a fore-sail such as a gib or genoa and in that latter case the device is suitably kept at its most compact. For retro-fitting to existing yachts, sails and control lines, it is desirable to provide the link as a separate element that may be tied or otherwise secured in place between the sail and the control line or as part of the control line, preferably by the link having an attachment means such as an eye at one or at both ends to which the control line may be tied or to which an intermediate tying means (further rope, wire et cetera) may be tied. However, the link may alternatively be integrally formed or assembled directly to the sail, e.g. via an eye in the sail, or to the control line. If the main control line for the sail is attached to the boom rather than directly to the sail then the link may be positioned at the boom. Preferably the link comprises a length of metal, metal alloy or plastics composite which acts as the mechanical fuse which breaks when the predetermined load on the line is exceeded. A length of steel (preferably stainless steel) or polycarbonate is particularly preferred. In the case that the fuse is of stainless steel or other metal/ alloys it suitably is a rod or bar that narrows centrally to a waist that is liable to break upon being pulled apart by the predetermined level of force. Indeed in one example the rod or bar narrows from a width or diameter of 5mm or greater to a waist of between 3 to 6mm or so. Where the fuses are of metal/ alloys each end of the rod or bar may be formed with a screw thread to threadedly assemble to the respective attachment means (e.g. eye) at each end.

Where the control line is for control of a fore-sail it is preferable that the fuse is a flexible element rather than a rod or bar of a metal, alloy or polymer. For such uses, primarily, the fuse may be of flexible material e.g. wire or chord or rope or other bundled fibres/filaments. It may be multi-stranded or with one strand of wire or chord or rope repeatedly lapped over itself to achieve a fuse of the required breaking strain.

The link's mechanical fuse is designed to break instantaneously on a certain level of strain so that when used in combination with a sail it releases the sail from its initial restrained position/ angle to spill wind from the sail, thereby reducing the load on the sail to a safer level.

The device of the present invention may be implemented in the basic form as a simple link as described above or, in a preferred embodiment as an extra feature/ refinement to the device, the link may further have a parallel tether link traversing the fuse, such a tether between a sail and a main control line which acts as a tether for when the mechanical fuse of the link has broken. For example it may provide a tether between the sail and the main control line to provide a secondary restraint on the sail that is less restrictive than the initial restraint on the sail. This additional link may be a shock line that elastically extends and/ or be a wire, chord or rope that is longer than the mechanical fuse and therefore only restrains the sail after the fuse breaks and the sail is able to move to an angle that reduces the load on the sail and is then substantially held at that angle. The parallel tether link may be wound, coiled or, flaked or otherwise configured into a compact but un-knotted state as part of the link until the fuse breaks. When the mechanical fuse breaks the compact (e.g. coiled) parallel tether link will extend/ uncoil and allow the sail to be released by the extent to which the extended tether link is longer than the mechanical fuse link, the tether may be encased in a rubber like compound that it tears through to absorb shock to diffuse any shock loading. Where the mechanical fuse link has an attachment means at each end (e.g. eye) for respectively attaching directly or indirectly to the sail and to the control line the parallel tether link may be also attached at each end to a respective one of those attachment means. Thus the link and parallel tether link are provided in a compact combined unit that can be space-efficiently and conveniently fitted between the sail and control line or within the control line.

The device is suitably provided with a housing in which the link or part thereof (and/ or the parallel tether link when provided) may be stowed in a compact state ready for deployment. In a preferred embodiment the link is stowed in a flexible container or sleeve to reduce its profile and obtrusiveness, and reduce its likelihood of impacting on surfaces or crew as it tracks back and forth over the deck during sailing manoeuvres. The housing may be made of a flexible material such as rubber which will break when the fuse breaks and this breaking action may also release the secondary tether if it is provided within the housing. Brief Description of the Drawings

A preferred embodiment of the invention will now be more particularly described, solely by way of example, with reference to the accompanying drawings in which:

Figure 1 is a detail view of a corner of a yacht's sail held by a control-line with the preferred embodiment of the safety release mechanism installed as a link between the sail and the control line.

Figure 2 is a view similar to Figure 1 but of the safety release mechanism deployed following over-loading of the sail.

Figure 3 shows the pre-deployed safety release mechanism in schematic section to illustrate the arrangement of the mechanical fuse and parallel tether in the device.

Description of the Preferred Embodiment

Referring firstly to Figure 1 , the illustrated embodiment of the safety release system comprises a compact insert device 1 that is retro-fitted to a sailing vessel between a corner or other extremity of the sail S or boom and the control line C that extends from the sail S to a cleat, winch or other adjustable anchoring device on the vessel's deck or other framework to restrain the sail/ hold the angular trim of the sail. The control line C in question will generally be the vessel's main sheet for controlling angular trim of the main-sail S but can alternatively be a foresail such as a genoa or gib. The illustrated device 1 has a securing ring, loop or eye, R1 at one end by which the device 1 is attached to the sail S and has a securing ring, loop or eye, R2 at the other end by which the device 1 is attached to the control line C. A chord, karabiner clip K or other fastening means is provided for tying clipping or otherwise fastening the device 1 at the eye R1 of the device 1 to an eye E or other fastening point on the sail and similar fastening means could be used for tying, clipping or otherwise fastening the device 1 at the eye R2 of the device 1 to the control line C. Most straightforwardly the control line C may simply be securely knotted directly to the eye R2 of the device 1 . Alternatively one or both of the eyes R1 , R2 might themselves each instead be a karabiner or other clip means to allow for clipping to an existing eye of a sail S et cetera.

At its centre the inserted device 1 comprises a pair of links L1 , L2 as can best be seen in Figure 3. These links L1 , L2 are initially in a compact state and held in that state neatly enshrouded in a housing/ sleeve 3 as shown in Figure 1 but are drawn from the housing/ sleeve 3 when the device deploys as shown in Figure 2. The housing/ sleeve 3 may be separate of the links L1 , L2 and ejected on deployment of the device 1 or, as illustrated, be coupled to an end of one of the links L1 , L2 or one of the eyes or other attachment means so as not to be lost, but retained tethered to the device 1 on deployment.

The first link L1 illustrated comprises a rigid piece of steel or polycarbonate, e.g. a rod or bar, that is fixed at one end to the eye R1 of the device 1 and at the other end to the eye R2 of the device 1 and as installed it effectively is an extension of the control line C linking the sail S and the control line C, restraining the sail S and thus having the loading on the sail S pulling on it. The first link / strip of steel L1 functions as a mechanical fuse and is selected to pull apart when the strain/ loading on it from the sail S exceeds a predetermined thresh-hold level. In alternative embodiments the first link L1 may be a flexible element rather than a rod or bar of a metal, alloy or polymer. Such flexible links/ mechanical fuses are particularly suitable for use where the control line is for control of a fore-sail so as to reduce obstruction and/ or localized damage as the sail moves. A fuse of flexible material may be of wire or chord or rope or of fibres/ filaments, strips or bands. Materials such as Dyneema® and Vectron® are particularly preferred. The material may be multi-stranded or with one strand repeatedly lapped over itself to achieve a fuse of the required breaking strain.

The first link L1 is a mechanical fuse that is designed to break on a certain level of strain to release the sail from its initial restrained position/ angle to spill wind from the sail, thereby reducing the load on the sail to a safer level. The breaking strain of the mechanical fuse is tailored to suit different sailing vessels and indeed different sizes and shapes and types of sail. For many small to medium classes of yacht a breaking strain that is between 1 and 2 tonnes may be appropriate as dictated by the predetermined safe threshold level for that vessel to substantially prevent capsizing or de-masting. In other words if the mast would break or vessel capsize at loadings on the sail, mast and control line above 2.5 tonnes / m ² , then the mechanical fuse should be configured to break at a loading that does not hamper the vessels performance but which is safely below that - say 2 tonnes /m ² . The second link L2 is a parallel tether link that traverses the fuse/ first link L1 linking between the sail S and main control line C as a tether for when the mechanical fuse/ first link L1 has broken, as is illustrated in Figure 2. The parallel tether link L2 is attached at each end to a respective one of the eyes R1 , R2. This provides a secondary restraint on the sail S that is less restrictive than the initial restraint on the sail by the mechanical fuse/ first link L1 and restrains the sail when the mechanical fuse/ first link L1 has broken. This second link/ parallel tether L2 may be a shock line that elastically extends and/ or be a wire, chord or rope that is longer than the mechanical fuse and therefore only restrains the sail S after the fuse L1 breaks so that the sail S is able to move to an angle that reduces the load on the sail S and is then substantially held at that angle by the control line C. The parallel tether link L2 is coiled / flaked into a compact but un-knotted state that is held neatly within the sleeve 3 until the fuse L1 breaks. When the mechanical fuse L1 breaks the compact parallel tether link L2 will extend/ uncoil but only allow the sail to be released by the extent to which the extended tether link L2 is longer than the mechanical fuse link L1 was. Where the parallel tether link L2 is of shock cord the shock cord is suitably of two component construction with an extremely tough woven outer sheath covering a multi-strand rubber core so as to be able to approximately double in length under strain but be light-weight, strong, wear- resistant and long lasting, alternatively this parallel tether may be encased in a rubber like compound that it breaks through to absorb shock.

It will be appreciated from the foregoing that the present invention meets its objective of providing a sail release mechanism for use as a safety device to help prevent capsizing, de- masting or damaging of the boom or rig of a sailing vessel such as a yacht. In operation, if there is too much load or force on the sail, the inner strip or wire acting as a fuse of the mechanism will break releasing the sail. If the mechanism should release under sail, the secondary shock cord, rope or wire of the mechanism that may be included in the higher spec versions of the device will act as a fall-back tether for the sail and will stop the sail releasing too far so that the sail will still be controllable after the initial release has deployed. This invention will thus greatly improve safety for sailing in very windy conditions.