Abstract:
Disclosed are luff extrusions that solve problems of batten chafing and friction locking. The inventive luff extrusions provide batten end receptacles with channels for headboard cars. The luff extrusions absorb the wind-generated compressive forces exerted by the battens on the batten pockets and eliminate the need for sail slides.

Description:
RELATED APPLICATIONS 
     This application is related to Ser. No. 12/437,086, “Mega Yacht Mast Tracking System with Articulating Sail Feeder,” and Ser. No. 12/437,062, “Sectionalized Mast Track,” both of which are being filed on the same day as the instant application. The subject matter of this application is also related to U.S. Pat. No. 6,371,037, “Sail Furling System,” to Cook et al. filed on Dec. 26, 2000. 
     The above-referenced applications and patent are incorporated herein by reference in their entireties. 
     BACKGROUND 
     Yachts with fully battened mainsails typically use battens of relatively rigid material, such as fiberglass, wood, and the like, positioned in batten pockets sewn in the mainsail. The battens and batten pockets extend horizontally from the trailing edge, or leech, to the forward edge, or luff, of the mainsail. The battens allow the sail to retain its shape in a variety of wind conditions and to flake more quickly and easily when lowered on a boom. More importantly, the battens support roach, the sail area that lies outside a straight line drawn from the head, the corner of the sail closest to the top of the mast, to the clew, the corner of the sail closest to the aft end of the boom. Roach enhances sailing performance by increasing the area of the sail and by changing the shape of the sail. Battens also prolong the life of the sail by reducing flogging in high wind or head to wind conditions. 
     Unfortunately, the wind captured by the sail to propel the yacht also pushes the battens against the forward edges of their respective batten pockets, causing the battens to poke through the luff end of the sail. Once the battens work through the batten pockets, the sail must be repaired or replaced. The battens also twist and compress the sail slides that keep the sail in the mast track, creating friction that impedes raising and lowering the sail. This friction can be great enough to lock the sail in the mast track and/or break the sail slides. Moreover, the forward end of the battens can move laterally past the sail slides and inwardly toward the mast, and can hit the mast and/or jam the bolt rope. 
     A variety of fittings for full batten mainsails have been proposed, including those disclosed in U.S. Pat. Nos. 5,127,351 to Breems; 4,823,720 to Foster; 3,092,064 to Benedict; 591,446 to Worthen; and 259,209 to Rand. Typically, these batten end fittings have joints that couple the batten to the sail slide to eliminate friction between the sail slides and the mast track caused by twisting and compression of the battens. Such joints usually do not permit the battens to rotate freely in every dimension, nor do they completely eliminate friction between the slides and the mast due to torque and compression. Joints that permit three-dimensional rotation generally require complex, rigid mechanical connectors that must be mounted on specialized slides integral with the connectors themselves. Unfortunately, these prior-art batten end fittings cannot withstand the high forces exerted by fully compressed or torqued battens of the larger sails used on larger yachts. 
     SUMMARY OF THE INVENTION 
     Embodiments of the present invention include luff extrusions and methods for attaching a sail luff comprising one or more battens to a mast of a yacht. Example luff extrusions include a batten guide formed of two substantially parallel batten guide arms. A luff passage connects the batten guide to a luff rope slot formed forward of the batten guide. Example luff extrusions also include a channel configured to guide a headboard car along an axis substantially parallel to the long axis of the mast. 
     In certain embodiments, the channel is formed on the exterior of the luff extrusion body for use with an external headboard car. For example, the channel may be formed of indentations substantially abeam of the luff rope slot on the exterior of the luff extrusion body. Alternatively, the channel may be formed of extrusions forward of the luff rope slot on the exterior of the luff extrusion body. 
     In other embodiments, the channel may be formed between the batten guide arms for use with an internal headboard car. Luff extrusions for use with internal headboard cars may also include hooks or catches at the ends of the batten guide arms to retain the headboard car in the batten guide. Channels formed between the batten guide arms may be configured to guide round or disc-shaped headboard cars. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing will be apparent from the following more particular description of example embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating embodiments of the present invention. 
         FIG. 1  is an elevation view of a yacht. 
         FIGS. 2A-2C  are plan views of a fully battened sail on a yacht in different wind conditions. 
         FIG. 3  is a plan view of a luff extrusion suitable for use with an external headboard car according to embodiments of the present invention. 
         FIGS. 4A and 4B  are plan and elevation views, respectively, of an external headboard car, headboard, and mast track with an example inventive luff extrusion cross section. 
         FIGS. 5A-5C  are plan views of a fully battened sail coupled to an example inventive luff extrusion on a yacht in the same wind conditions shown in  FIGS. 2A-2C . 
         FIG. 6  is a plan view of a luff extrusion suitable for use with an internal headboard car according to alternative embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A description of example embodiments of the invention follows. 
       FIG. 1  shows a yacht  10  with a mast  20  and a boom  26 . The boom  26  stores a sail  30 , which may be raised with a halyard (not shown) to capture wind and propel the yacht  10 . A headboard  29  reinforces the head  38  of the sail  30  to prevent high loads from tearing apart the head  38 . A headboard car  28  coupled to the headboard  29  and the halyard travels smoothly along a mast track  24  fixed to the mast  20 , facilitating raising and lowering of the sail  30 . The mast track  24  guides the headboard car  28  and a luff rope (not shown; also known as a sail bolt rope or bolt rope) stitched into the forward edge, or luff  36 , of the sail  30  along an axis parallel to the long axis of the mast  20 . Although the headboard car  28  shown in  FIG. 1  travels on the outside of the mast track  24 , alternative headboard cars may be configured to travel within a groove internal to the mast track  24 . 
     The sail  30  shown in  FIG. 1  is a fully battened mainsail  30  with battens  32  that run generally parallel to the bottom edge, or foot  40 , of the sail  30  from the luff  36  (leading edge) to the trailing edge, or leech  37 , of the sail  30 . The battens  32  are stitched into batten pockets  34  in the sail  30 . Standard battens (not shown) run only partway from the luff  36  to the leech  37 , trading long-term performance for reduced chafing and easier handling. Battens may be oriented in other directions or combinations of directions; for example, alternative battens may run perpendicularly from the leech  37  to intersect the foot  40  and the luff  36  at substantially complementary angles. 
     Full battens  32  support roach  42 , the sail area that lies outside a straight line from the head  38  to the lower aft corner, or clew  39 , of the sail  30 . Typically, the supporting battens  32  are about three times longer than the roach  42  that they support. Roach  42  enhances sail performance by adding 15-30% more sail area to a triangular sail, such as the sail  30  shown in  FIG. 1 . More importantly, mainsails with roach  42  have elliptically shaped heads and planforms that improve performance on all points of sail, particularly to weather. 
     Unfortunately, full-length battens  32  reduce the life of the sail  30  by chafing against the batten pockets  34 . The same forces that pull the sail taut to propel the yacht  10  push the battens  32  towards the mast  20 , causing the battens  32  to chafe against the batten pockets  34 . Eventually, this chafing causes the battens  32  to tear or poke through the forward ends of the batten pockets  34 . Reinforcing the batten pockets  34  alleviates this problem on vessels with smaller sails  30 , but reinforcement is not sufficient to withstand chafing due to the larger compressive forces exerted on battens  32  in larger sails. In addition, compression increases friction on the sail slides that run in mast tracks  24  without headboard cars  28 , making it difficult to raise, lower, or reef the sail  30 . 
       FIGS. 2A-2C  are plan views of a fully battened sail  30  of a yacht traveling in a direction  102  in various wind conditions. The sail  30  is attached to the mast  20  with a luff rope  112  that slides in a slot in a luff extrusion  60  attached to the mast  20 . Sail slides (not shown) in the slot permit the sail to be raised or lowered. Wind  100  exerts compressive and/or torquing loads on the sail  30  and the battens (not shown) stitched into the sail  30 . 
     In  FIG. 2A , the yacht  10  is facing directly into the wind  100 , so the wind  100  does not exert any force on the sail  30 , which, therefore, remains limp and does not exert any force on the luff  36 , A yacht  10  facing directly into the wind is said to be “in irons” or “heaved to.” The yacht  10  does not advance under this point of sail, but lies motionless in the water, except for the effects of the tide or wind  100  on the hull. 
       FIG. 2B  shows wind  100  blowing at an acute angle with respect to the direction of travel  102 . In this case, the boat is said to be “close-hauled.” The clew  39  of the sail  30  is attached to the after end of the boom (not shown), so the sail  30  bellies out slightly due to pressure exerted by the wind  100 . As the sail  30  pulls taut due to the wind pressure, it exerts a compressive force in a direction  114  on the luff  36 , driving the luff  36  forward and out of line with the opening in the luff extrusion  60 . This compressive force also causes the battens in the sail  30  to chafe against the forward edges of their respective batten pockets; eventually, the battens wear through the batten pockets, ruining the sail  30 . Compressive forces also strain the junction between the luff  36  and the tuff rope  112  and increase friction between the sail slides and the slot in the tuff extrusion  60 . 
       FIG. 2C  shows wind  100  blowing from dead aft, i.e., exactly along the direction of travel  102 . The wind  100  causes the sail  100  to belly even more, compressing the tuff  36  as in  FIG. 2B . In this case, however, compression produces a force vector  116  that is almost perpendicular to the direction of travel  102 , resulting in more severe chafing on the sail  30 . Compression strain at the junctions between the luff  36  and the tuff rope  112  is also more severe in the situation shown in  FIG. 2C  than that illustrated in  FIG. 2B . Friction between the sail slides and the slot in the luff extrusion  60  may be great enough to lock the sail slides in place, preventing the sail  30  from being raised or lowered. 
       FIG. 3  is a plan view of a batten receptacle, or luff extrusion  300 , suitable for use with an external headboard car  28 . The luff extrusion  300  solves the problem of batten poke or chafing by providing a batten guide  302  that receives battens along the length of the mast  20 , such as the full battens  32  shown in  FIG. 1 . Unlike the batten receptacles disclosed in U.S. Pat. No. 6,371,037 to Cook et al, the present inventive luff extrusion  300  also eliminates problems associated with friction-locked sail slides by providing a channel  310  for a headboard car  28  ( FIG. 1 ) that disposes with the need for sail slides. 
     The luff extrusion  300  includes a pair of substantially parallel batten guide arms  304  that form the batten guide  302 . A luff passage  306  connects the batten guide  302  to a luff rope slot  308  configured to hold a luff rope sewn into the luff  36  of a sail  30 . As wind fills the sail  30 , compressing the battens  32  ( FIG. 1 ), the battens  32  push against the forward edge of the batten guide  302 , reducing chafing on the batten pockets  34  ( FIG. 1 ). The batten guide arms  304  also stabilize battens  32  subject to rotational forces, such as those shown in  FIG. 2C . 
     As shown in  FIG. 3 , the headboard car channel  310  is formed substantially next to (i.e., abeam of) the luff rope slot  308 , defining a travel axis for the headboard car  28  ( FIG. 1 ) that is substantially coincident with the axis formed by the luff rope slot  308 . Because the headboard car  28  and the luff rope (not shown) travel along the same axis, torque on the headboard car  28  or the headboard  29  ( FIG. 1 ) in the plane of the sail  30  is less likely to cause the headboard car  28  to shift, jam, or stick in the headboard car channel  310 . As a result, the luff rope and headboard car  28  travels freely up and down an axis parallel to the longitudinal axis of the mast  20 . 
     The tuff extrusion  300  may also include a hinge pin tunnel  340 , a connector tunnel  342 , and a feeder ball seat  344 . The hinge pin tunnel  340  can be used to hold a hinge pin that connects a mast track  24  with the inventive tuff extrusion cross section  300  to a hinge on the mast  20 . The hinge and hinge pin allow the mast track  24  to pivot about the longitudinal axis of the mast  20 . Similarly, the connector tunnel  342  can be used to connect sections of a sectionalized mast track to each other so that all the sections pivot on one centerline, as described in Ser. No. 12/437,062, “Sectionalized Mast Track,” incorporated herein by reference in its entirety. 
     In a preferred embodiment, the luff extrusion  300  is 141 mm long and varies in width from about 46 mm just forward of the headboard car channel  28  to about 32 mm at the channel  28  itself. The headboard car channels  310  are each about 22 mm wide and about 7 mm deep. The batten arms  304  are about 43 mm long, forming a batten guide  302  with a length of 43 mm and a width of about 26 mm. The luff passage  306  may be about 5 mm wide and about 6 mm long; the luff rope slot  308  can be about 7.5 mm in radius. Edges of mast tracks  24  with the present inventive luff extrusion cross section  300  may be beveled, chamfered, and/or radiused as appropriate. 
     Mast tracks  24  with the inventive luff extrusion cross section  300  may be fabricated of 6005 aluminum alloy or any other suitable material. Generally, suitable materials are at least moderately strong; capable of bending, flexing and twisting; suitable for machining, welding, and brazing; and corrosion resistant (or able to be treated or coated with corrosion-resistant material). Mast tracks with the inventive luff extrusion cross section may be made by machining, extrusion, or any other suitable manufacturing techniques. 
       FIG. 4  shows perspective and plan views of a sail  30 , headboard car  28 , and mast track  24  with the present inventive luff extrusion cross section  300 . The headboard car  28 , which is coupled to the head  38  of a sail via a headboard  29 , includes a guide  452  formed of two substantially parallel arms  454  that fit around the outside of the luff extrusion  300 . The arms  454  on the headboard car  28  have channels  460  that mate with the complementary channels  310  on the luff extrusion  300 . Bearings (not shown) between the channels  310  on the luff extrusion  300  and the channels  460  on the headboard car  28  allow the headboard car  28  to travel freely along an axis substantially parallel to the mast  20  ( FIG. 1 ). 
     Because the headboard car  28  travels smoothly along the bearings between the channels  460  and  310 , the sail  30  can be raised and lowered with a halyard (not shown) attached to the headboard car  28 . In contrast to conventional sails, which are raised with halyards attached directly to the head  38  or the headboard  29 , sails  30  coupled to headboard cars  28  do not need sail slides to ensure smooth travel of the sail up and down the mast. As a result, sails raised with headboard cars  28  configured with luff extrusions  300  of the present invention do not suffer from the compression- and torque-induced friction that locks sail slides into place. 
     In a preferred embodiment, the headboard car is made of aluminum or any other suitably strong, light, and corrosion-resistant material. The guide  452  is wide enough and long enough to accommodate the luff extrusion  300 . For example, the arms  454  may be about 120 mm long and spaced at least 46 mm apart. The edges of the headboard car  28  may be beveled, chamfered, and/or radiused as appropriate. 
       FIGS. 5A-5C  are plan views of a fully battened sail coupled to a luff extrusion  300  and headboard car  28  on the mast  20  of a yacht  10  in the same wind conditions as those depicted in  FIGS. 2A-2C . In  FIG. 5A , the wind  100  is blowing directly opposite the direction of travel  102 , so the battens in the sail  30  do not exert any pressure on the luff extrusion  300 . As the wind  100  shifts direction so that the boat is sailing close hauled in  FIG. 5B , the wind  100  causes the sail  30  to pull taut, pushing the battens  32  towards the mast  20 . This compression pushes the battens along a vector  404  into the luff extrusion  300 , which withstands the compression that would otherwise cause chafing and wear along the sail luff  36 . When the wind  100  blows from the stern, as shown in  FIG. 5C , the luff extrusion  300  absorbs both compressive forces along vector  406  and rotational forces that cause the sail  30  and battens  32  to twist against the arms  304  of the luff extrusion  300 . 
       FIG. 6  is a plan view of an alternative luff extrusion  500  with an internal headboard car  528 . The luff extrusion  500  includes a pair of substantially parallel batten guide arms  504  that form a batten guide  502 , which connects to a luff rope slot  508  via a luff passage  506 . Each batten guide arm  504  terminates in a hook shape  512  or similar configuration that defines a headboard car channel  510  inside the batten guide  502 . The internal headboard car  528 , which may be round or disc-shaped (i.e., shaped like a hockey puck), travels in the space defined by the batten guide  502  along an axis defined by the headboard car channel  510 . The hooks  512  retain the headboard car  528  within the batten guide  502 . 
     The batten guide  502  receives battens  32  sewn in the sail below the headboard car  528 . As compressive forces push the battens  32  forward, the battens  32  push against the batten guide  502 , rather than chafing against the forward edges of their respective batten pockets  34 . Similarly, the batten guide arms  504  hold the battens  32  as the battens  32  twist and rotate, reducing friction between the battens  32  and the respective batten pockets  34 . 
     The alternative cross section  500  also includes a connector tunnel  542  and a hinge pin tunnel  540 , which are configured to retain a tensioning line  86  and limiting pins  90 , respectively, as described in Ser. No. 12/437,086, “Mega Yacht Mast Tracking System with Articulating Sail Feeder.” The connector  542  may also be configured to receive ball joints  94  with a ball joint seat (not shown). 
     Of course, other configurations of headboard car channels  310  are possible. For example, the headboard car  28  could ride on channels formed by everted channels, protrusions, or rails that stick out from a mast track  24  with the inventive luff extrusion cross section. The channels may include more than two channels on each side, or may be formed further forward or aft along the inventive luff extrusion. The channels may be integral to the luff extrusion  300  or may formed by additional fixing parts to the mast  20  or mast track  28 . 
     While this invention has been particularly shown and described with references to example embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims. 
     For example, the generic term yacht as used herein includes sailing vessels, boats, and ships of various sizes, including mega-yachts, which may be 40 feet or longer. Similarly, the generic term sail includes mainsails, which are used primarily to propel yachts. Likewise, the generic term mast includes mainmasts and other masts. In addition, the terms luff rope, sail bolt rope, and bolt rope may be used interchangeably. 
     Further, the various dimensions, materials, and surface or edge processing are for purposes of non-limiting illustration. Other dimensions, materials, and manufacturing processing are suitable.