Sails

Abstract

This invention is an improved sail which uses wedge-shaped panels on the luff with warp threads running the length of the wedges. By properly proportioning the wedges, luff tension is distributed through the centroid of the .[.jib.]. .Iadd.sail .Iaddend.triangle and thus controls draft position and leading edge flatness. The result is a broader wind range sail with longer optimum performance life.

I claim: 
     
       1. An improved jib sail for a sailing yacht having a luff region extending between the head and tack of said jib sail, said luff region comprising upper and lower groups of triangular panels of woven cloth, each of said panels having an apex, a base, and a trailing edge, each of said panels further having warp threads extending substantially parallel to said trailing edge, said apex of each of said panels of said upper group convergent at the head of said jib sail and said apex of each of said panels of said lower group convergent at the tack of said jib sail, said base of each of said panels being joined along a common seamline, said seamline being substantially perpendicular to the luff of said jib sail and passing nearly through the locale of resultant wind force on said jib sail; wherein said warp threads provide maximum sail strength along a line extending from the head of said jib sail into a region near the locale of resultant wind force on said jib sail and thence to the tack of said jib sail thus producing a truss-like structure of panels transferring the wind load to the head and tack, thereby reducing the need for headstay support. 
     
     
       2. An improved jib sail as defined in claim 1, capable of improved windward performance over a broader wind speed range by virtue of its greater strength per given weight of sail cloth. 
     
     
       3. An improved jib sail as defined in claim 1, capable of improved windward performance for a longer lifetime due to its shape dependence upon threadline strength rather than cloth bias strength. .Iadd. 
     
     
       4.  A fore and aft sail having a head, a tack, a clew and a luff area along a luff edge between the head and the tack, comprising, the luff area comprised of sail material means having lines of directional stability extending between the vicinity of the head and the vicinity of the tack, at least a portion of said lines of directional stability extending away from the vicinity of the head at a small angle to the luff edge which angle faces the tack, at least a portion of said lines of directional stability extending away from the vicinity of the tack at a small angle to the luff edge which angle faces the head, and said lines of directional stability extending at said small angles for at least a portion of the distance between the head and the tack, said lines of directional stability being a direction in which the sail material means has greater resistance to deformation under tension forces than in other directions. .Iaddend. .Iadd. 
     
     
       5.  A sail as claimed in claim 4 wherein said lines of directional stability of the sail material means in said luff area are aligned substantially with the lines of principle stress extending between the vicinity of the head and the vicinity of the tack when the sail is under wind load and properly tensioned. .Iaddend. .Iadd.6. A sail as claimed in claim 5 wherein said sail material means includes a plurality of separate panels of a sail material joined together to form the luff area. .Iaddend. .Iadd.7. A sail as claimed in claim 6 wherein said panels are cut from a woven material having a warp and weft, and said lines of directional stability are aligned with the warp or weft. .Iaddend. .Iadd.8. A sail as claimed in claim 7 wherein there are at least four said panels with a pair of panels in an upper area and a pair of panels in a lower luff area, each panel being substantially triangular with first and second long sides and one short side and with the warp aligned with the first long side, and one panel of each pair having the second long side along the luff edge and the first long side joined to the second long side of the other panel of that pair. .Iaddend. .Iadd.9. A sail as claimed in claim 8 wherein the short side of at least one panel in the upper luff area is joined to the short 
     
     
        side of at least one panel in the lower luff area. .Iaddend. .Iadd.10.  A sail as claimed in claim 5 wherein said sail material means is a woven material having a warp and weft, and said lines of principle stress and directional stability are aligned with the warp or weft. .Iaddend. .Iadd.11. A sail as claimed in claim 4 wherein said sail material means includes a plurality of separate panels of a sail material joined together to form the luff area. .Iaddend. .Iadd.12. A sail as claimed in claim 11 wherein said panels are cut from a woven material having a warp and weft, and said lines of directional stability are aligned with the warp or weft. 
     
     
        .Iaddend. .Iadd.13.  A fore and aft sail having a head, a tack, a clew, and a luff area along a luff edge between the head and tack, comprising, the luff area comprised of sail material means having lines of directional stability in the direction of which the sail material means has substantially greater resistance to deformation under tension than in most other directions, and said lines of directional stability extending between the vicinity of the head and the vicinity of the tack with at least a substantial proportion of said lines positioned at a small angle to the luff edge, said lines of directional stability extending away from the vicinity of the head at a small angle to the luff edge which angle faces the tack and said lines of directional stability extending away from the vicinity of the tack at a small angle to the luff edge which angles 
     
     
        faces the head. .Iaddend. .Iadd.14.  The sail of claim 13 wherein said sail material means is comprised of a plurality of elongated panels extending generally in the direction between the head and the tack, and each panel is of a woven material having a warp and weft with the warp substantially aligned with said lines of directional stability. .Iaddend. 
     
     
        .Iadd.15.  A fore and aft sail having a head, a tack, a clew and a luff area along a luff edge between the head and the tack, comprising, the luff area comprised of sail material means having lines of directional stability extending between the vicinity of the head and the vicinity of the tack with at least a portion of said lines of directional stability positioned at a small angle to the luff edge for a portion of the distance between the head and the tack, said lines of directional stability being a direction in which the sail material means has greater resistance to deformation under tension forces than in other directions, said lines of directional stability of the sail material means in said luff area being aligned substantially with the lines of principle stress extending between the vicinity of the head and the vicinity of the tack when the sail is under wind load and properly tensioned, said sail material means including a plurality of separate panels of a sail material joined together to form the luff area with each of said panels being cut from a woven material having a warp and weft, said lines of directional stability are aligned with the warp or weft, at least four said panels with a pair of panels in an upper area and a pair of panels in a lower luff area, each panel being substantially triangular with first and second long sides and one short side and with the warp aligned with the first long side, and one panel of each pair having the second long side along the luff edge and the first long side joined to the second long side of the other panel of that pair. 
     
     
        .Iaddend. .Iadd.16.  A sail as claimed in claim 15, wherein the short side of at least one panel in the upper luff area is joined to the short side 
     
     
        of at least one panel in the lower luff area. .Iaddend. .Iadd.17.  An improved sail for a sailing yacht having a luff region extending between the head and tack of said sail, said luff region comprising upper and lower groups of triangular panels of woven cloth, each of said panels having an appex, a base, and a trailing edge, each of said panels further having warp threads extending substantially parallel to said trailing edge, said apex of each of said panels of said upper group convergent at the head of said sail and said apex of each of said panels of said lower group convergent at the tack of said sail, said base of each of said panels being joined along a common seamline, said seamline being substantially perpendicular to the luff of said sail and passing nearly through the locale of resultant wind force on said sail; wherein said warp threads provide maximum sail strength along a line extending from the head of said sail into a region near the locale of resultant wind force on said sail and thence to the tack of said sail thus producing a truss-like structure of panels transferring the wind load to the head and tack, thereby reducing the need for headstay support. .Iaddend. .Iadd.18. An improved sail as defined in claim 17, capable of improved windward performance over a broader wind speed range by virtue of its greater strength per given weight of sail cloth. .Iaddend. .Iadd.19. An improved sail as defined in claim 17, capable of improved windward performance for a longer lifetime due to its shape dependence upon threadline strength rather than cloth bias strength. .Iaddend.