Abstract:
A positive batten inversion system for control of the battens used to stiffen the leech of a sail for a sailboat comprises a pair of control lines for each batten that extends beyond the backstay run up from the tack, along either side of the luff of the sail, to blocks secured to the sail near the luff and slightly below an imaginary line connecting the batten centerline to the luff. From the blocks, the lines run out to the leech and are secured to the leech just above the after end of the battens. Accordingly, the lines cross the battens at a very acute angle. Tensioning the lines causes the batten to be inverted and/or compressed, allowing it and the leech of the sail to pass by the backstay.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to control of the battens used to stiffen the Leech portions of the fore-and-aft sails of a sailboat. More specifically, it would be useful to provide positive control of full-length battens in particular, rather than relying on their changing their camber during manuevers. In particular, it would be desirable to provide a positive control for urging the battens of a mainsail past the backstay during manuevers.  
       BACKGROUND OF THE INVENTION  
       [0002]     The sailboats with respect to which this invention is relevant are typically rigged to fly at least one generally triangular fore-and-aft sail, e.g., a “mainsail”. Although the invention is described herein primarily in that connection, it is not limited thereto; the invention may also have use in connection with battened forseails or “jibs”, and with other fore-and-aft sails in boats of other types, e.g., mizzen sails on boats with multiple masts.  
         [0003]     Refering now to the case of the mainsail, the forward side or “luff” of the mainsail is supported by a mast; the lower edge of the mainsail, or “foot”, is secured to a boom pivoted to the mast; and the rearward edge of the sail, or “leech”, flies freely. The uppermost corner of the sail, where the luff and leech meet, is called the “head”; the lower forward corner, where the foot and luff meet, is called the “tack”, and the after lower corner, where the leech and foot meet, is termed the “clew”.  
         [0004]     To stiffen the leech, so that it retains its desired aerodynamic shape under a wide range of conditions, a number, usually four to six, of “battens”, comprising resilient strips of a lightweight planar material of carefully chosen flexibility, are commonly inserted into pockets extending forward from the leech, usually parallel to the foot or perpendicular to the leech. It is increasingly popular for at least the uppermost batten to be full-length, that is, to extend from the leech to the luff.  
         [0005]     All else being equal, a sail of larger area will be more powerful than a smaller sail, so there is a constant trend to increase sail area. One limitation imposed on the size of the mainsail that can be carried is the presence (in nearly all cases) of a “backstay”, a tension member running from the top of the mast toward The stern of the boat, part of a set of such members (the “standing rigging”) that support the mast. Traditionally, the leech of the sail, particularly near the head, has been designed so that it almost completely fills the area between the mast and backstay, in order to maximize sail area while preventing the leech from interfering with the backstay as the sail passes over the centerline of the boat during “tacking” and “jibing” manuevers.  
         [0006]     More recently, mainsails are increasingly being cut so that their leeches extend beyond the backstay. Where the leech is aft of an imaginary line connecting head and clew, it is said to have “roach”, so the trend is to more and more roach. A problem with doing so is that the upper battens in particular tend to interfere with the backstay during tacking and jibing manuevers, during which, as noted above, the sail crosses the centerline of the boat; as the leech of the sail slides past the backstay, the stiff battens tend to catch on the backstay, preventing the sail from coming completely through the manuever and causing various difficulties. This is particularly a problem with full-length upper battens, where the inner end of the batten bears more or less directly against the mast. To the extent this problem has not been solved it prevents adding roach, as desired.  
         [0007]     One solution to this problem that has been tried with some degree of success is to attach one end of a “whip”, a flat springy strip of material, not unlike a sail batten, to the masthead, and the other end to the backstay, in such a way that the whip tends to urge the backstay away from the masthead. Then, during manuevers, tension on the backstay is substantially eased, so that the whip can pull it out of the way of the leech of the sail as the boat tacks or jibes; after the manuever, the backstay must then be retensioned. This approach has many drawbacks: it adds weight and windage at the masthead, which is very undesirable, it adds significantly to the duties required of the crew, and if the whip breaks or fails it may be impossible to tack or jibe the boat without at least partially lowering the sail, which is very awkward and time-consuming, and may even be dangerous.  
         [0008]     Thus, a need exists in the art for a device or system that will allow sails to be built with leeches extending substantially aft of the backstay, employing full-length battens as desired, and which will permit the battens to be urged past the backstay during tacks and jibes. Additional constraints to be met are that this system or device not add excessive weight, cost, or complexity, either as to use while sailing or when removing and stowing the sails, and that it be reliable and easy to install and use.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention satisfies the above needs of the art, and complies with the listed constraints, by its provision of a positive batten inversion system. A pair of control lines for each batten that extends beyond the backstay run up from the tack, along either side of the luff of the sail, to pulleys or “blocks” secured to the sail near the luff and slightly below an imaginary line connecting the batten centerline to the luff. From the blocks, the lines run out to the leech and are secured to the leech just above the after end of the battens. Accordingly, the lines cross the battens at a very acute angle.  
         [0010]     The system of the invention can be used in several different ways. In one possible practice, the tack or jibe manuever is completed as usual; if the batten hangs up on the backstay, the control line on the appropriate side of the sail, the free end of which hangs near the tack, is pulled downwardly, causing the batten to be collapsed somewhat, allowing the leech to slide past the backstay. As soon as the batten passes the backstay the control line can be released.  
         [0011]     In another method of practice of the invention, the control lines are pulled prior to the tack or jibe. This causes the battens first to be “inverted”, that is, reverse their direction of curvature, and then be compressed, allowing the leech to pass by the backstay. More specifically, while the boat is sailing on a first tack, the sail is cambered to leeward, i.e., forms an aerodynamically curved shape; the batten&#39;s characteristics are chosen specifically to assist in forming the proper sail shape. Absent the invention, when a tack or jibe is initiated, so that the leech of the sail must brush past the backstay, the tip of the cambered batten, being bent toward the backstay, tends to catch on the backstay. The control lines provided according to the invention are operated to cause the batten to invert, taking a camber of the opposite sense, at or prior to the time the batten and leech pass by the backstay.  
         [0012]     Finally, the control lines provided according to the invention can be used as additional sail-shaping tools, both to preclude unwanted batten inversion (as sometimes happens in light air conditions) or to provide a desired amount of curvature to the sail.  
         [0013]     The control lines can be confined near the luff of the sail in pockets or sleeves of sailcloth sewn to the sail, or otherwise, e.g., through a series of rings or the like. The lines and blocks can be very light, since the applicable loads are very small, and do not interfere with movement of the sail, or its removal from the mast and stowage. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     The invention will be better understood if reference is made to the accompanying drawings, in which:  
         [0015]      FIG. 1  shows a mast, boom, backstay, and mainsail, as seen from the right or “starboard” side of a sailboat;  
         [0016]      FIG. 2  shows the upper portion of the sail and mast, from the starboard side, while the boat is on “port tack”, i.e., with the wind coming over the left or “port” side;  
         [0017]      FIG. 3  shows a similar view, showing the battens becoming inverted as tension is applied to the control lines;  
         [0018]      FIG. 4  shows a similar view, showing the battens having been inverted as further tension is applied to the control lines;  
         [0019]      FIG. 5  shows a similar view, showing the battens, having been inverted, becoming compressed as further tension is applied to the control lines, so that the battens and leech can pass by the backstay;  
         [0020]      FIG. 6  shows a similar view, showing the battens having become extended on the starboard tack, as tension is released from the control lines; and  
         [0021]      FIG. 7  illustrates a several alternative implementations of the invention, with the sail on port tack, as in  FIG. 2 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0022]      FIG. 1  shows, as mentioned, the mast  10  and associated components of a sailboat from the starboard side. A mainsail  12  is secured along its luff  14  to the after side of mast  10 . The head  16  of sail  12  is hoisted to the top of mast  10  by a halyard (not shown), and its foot  18  is controlled by a boom  20  pivoted to the mast  10  at or near the tack  22  of sail  12 .  
         [0023]     As noted, in the usual case the mast  10  is supported by a number of tension members, or standing rigging, including the backstay  24 , which commonly runs from a masthead crane  26  at the top of mast  10  to be secured to the boat&#39;s deck, as indicated at  28 . If, as is currently popular, and as shown, the leech  32  of the mainsail extends past the backstay  24 , i.e., the sail has roach, the leech  32  will brush against the backstay  24  during tacking and jibing manuevers and may be impeded from passing by the backstay freely. This prevents the sail from being controlled readily, as is highly desirable, and in some cases could be dangerous.  
         [0024]     It is usual for a number of battens  30 , usually strips of a stiff planar material, to be disposed in pockets sewn or otherwise affixed to the sail and running forwardly from the leech, to support the sailcloth and ensure that the leech retains the desired aerodynamic shape. One or more of the battens may be “full-length”, i.e., run from the leech to the luff, so as to stiffen the entire “chord” of the sail in this region, as shown by uppermost batten  30   a  in  FIG. 1 .  
         [0025]     It will be apparent that the presence of the battens exacerbates the problem of pulling a sail with substantial roach past the backstay during manuevers, especially where one or more full-length battens are used, since the stiffness provided by the battens resists the collapsing of the sail that is required in order that it can pass by the backstay.  
         [0026]     According to the present invention, at least one control line  40  is added to either side of the sail. Only the line(s) on the starboard side of the sail are shown in the drawings hereof; similar lines would be installed similarly on the port side of the sail.  
         [0027]     Thus, according to the invention, a first control line  40  runs from a lower end disposed near the tack  22  of the sail, upwardly near the luff  14  to a block  42  secured to the sail, and thence to the leech  32 , where the upper end of control line  40  is secured. It will be appreciated that exerting tension on the lower end of control line  40 , that is, pulling downwardly, will urge the leech  32  toward the mast. In some cases, thus pulling the leech inwardly may itself be sufficient to pull the outer end of the batten  30  past the backstay  24 , freeing the sail to tack or jibe, as may be. However, this may not always suffice, especially where there is a full-length batten, as at  30   a , extending between leech  32  and luff  14 ; the stiff batten secured to the sail may preclude collapse of the sail by tension applied at an arbitrary point on the leech  32 .  
         [0028]     Therefore, according to another important aspect of the invention, the block  42  is secured to the sail near the luff on one side (below, in the embodiment shown) of an imaginary line running along the centerline of the batten  30   a , while the upper end of the control line  40  is secured to the leech  32  on the opposite side of that line (thus, in the embodiment shown, above the centerline of the batten). Accordingly, the control line crosses the batten  30   a  at a rather acute angle A, which might be between 5-30 degrees.  
         [0029]     The effect of disposing the control line  40  so that it thus crosses the batten, rather than running directly along the batten, is that the control line contacts the batten (that is, contacts the surface of the batten pocket in which the batten is disposed, in the usual construction) at or near the point of maximum curvature of the batten. Accordingly, and as will be more clear from discussion of  FIGS. 2-6  below, tension on the control line  40  tends to “invert” the batten, that is, causes the batten to switch from being cambered in one sense, that is, curved toward one side of the sail, to being cambered in the opposite sense. Having the control line cross the batten at an angle also imparts a twisting force to the batten, further easing in its inversion. Experiments performed by the inventor indicate that thus having the control line cross the batten at an angle provides improved results as compared to a system in which the control line  40  were disposed so that it was parallel to the batten.  
         [0030]     As indicated, if more than one batten extends past the backstay, second (and additional) control lines  40 ′ can be provided, with a second block  42 ′ located in the corresponding position with respect to the lower batten(s)  30 . Control line  40 ′ can be spliced to control line  40 , so that a tug on a single line will cause both battens to be inverted. As noted, this procedure is very simple and can be accomplished by a crewmember as a matter of course each time the boat is tacked or jibed, simply by pulling downwardly on the appropriate control line.  
         [0031]     As illustrated, the control line(s)  40 ,  40 ′ can be confined neatly near the luff  14  of the sail  12  by enclosure in elongated sleeves  44  formed by sewing strips of sailcloth to the sail near the luff. Alternatively, the control lines could be led to the vicinity of the tack by a series of rings or the like secured to the sail.  
         [0032]     Further, again as noted above, a similar arrangement of one or more control line(s), block(s), and sleeve is provided on either side of the sail, so that the battens can be inverted in either sense.  
         [0033]      FIGS. 2-6  show stages in the inversion of the uppermost two battens of a sail during a tack, from “port tack” (in which the wind is coming over the left or port side of the boat) to “starboard tack”. These Figs. all show the sail from the starboard side, essentially as if lookng upwardly at the masthead. Thus, in  FIG. 2 , the sail is shown as during port tack, in that the sail  12  is curved to “leeward”, that is, away from the wind, toward the viewer. The battens  30 , both of which are full-length in this example, are similarly cambered to leeward, toward the viewer. The backstay  24  is behind the sail, so that if the boat is tacked, forcing the sail to pass by the backstay, the potential exists for the leech  32 , especially as stiffened by the full-length cambered battens  30 , to hang up on the backstay  24 .  FIG. 2  also shows reinforcing patches  46 , provided to prevent the load from the control line from distorting the shape of the leech.  
         [0034]     In  FIG. 3 , tension T has begun to be exerted on the control lines  40 , which forces battens  30  to begin to be inverted, by assuming an “S”-shape, as illustrated. As illustrated, the lines contact the battens (which will typically be confined in pockets of sailcloth, not shown) at or near the point of maximum depth of curvature. Accordingly, applying tension on the control lines causes a transverse force to be exerted directly to the battens at or near the point which is most effective in causing the battens to take the “S-shape” shown, and then immediately to invert, taking the opposite camber.  
         [0035]     In  FIG. 4 , the battens have been inverted, that is, have “popped” into the opposite camber, although the boat has not yet tacked (as indicated by the fact that the backstay  24  is still behind the sail). In  FIG. 5 , further tension T is applied (the application of tension being essentially a continuous process), causing the inverted battens  30  to become compressed, so that the leech  32  of the sail passes under the backstay  24 . Now the boat can be tacked, so that the sail passes under the backstay, and the tension eased in lines  40 ; the sail then takes the normal starboard tack configuration in  FIG. 6 .  
         [0036]     It will be appreciated that in practice of the invention according to the foregoing description of the use of the invention, the control lines provided according to the invention are tensioned to invert the battens before tacking, as this will lead to the smoothest operation. It is nonetheless within the invention to operate the control lines only after tacking, and indeed to so only when the batten and leech in fact are hung up on the backstay; in many boats this does not occur on each tack or jibe. It is also within the invention to maintain tension on the control lines  40  after tacking, to control the shape of the sail, or to preclude repetitive inversion of the battens (as can happens in particular during light-air sailing, interfering with the aerodynamic shape of the sail); this can readily be accomplished by assembling small cleats on either side of the sail near the tack  22 , as indicated at  50  in  FIG. 1 .  
         [0037]     Finally,  FIG. 7  shows several alternative constructions also within the invention.  
         [0038]     At  46  there is shown a partial-length batten, with the control line at an angle thereto as above; in this case, the batten would be inverted by operation of the control line, as above. At  48  there is illustrated a partial length-batten with the control line  40  attached to its inboard end; in such case the control line serves primarily to pull the entire leech section of the sail under the backstay, rather than first invert and then compress the batten, as in the above.  
         [0039]     It is also within the scope of the invention employ a similar control line arrangement for inversion of battens on sails other than mainsails. For example, battens are sometimes used on foresails, or “jibs”; these also can become hung up on the standing rigging, or on the mast. The invention can readly be adapted to provide positive control of such battens on foresails.  
         [0040]     Thus, while a preferred embodiment of the invention and several alternatives have been shown in detail, the invention is not to be limited thereby, but only by the following claims.