SAIL SHAPE CONTROL DEVICE

Abstract

A sail control device for flattening the after portion of a triangular sail. The sail control device includes at least one tensioning member which extends from a front portion of the sail across the sail to the after portion of the sail. The tensioning member may be attached to a Cunningham line for tensioning.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of U.S. Provisional Patent Application Ser. No. 61/294,733 filed Jan. 13, 2010, which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a device for use in controlling the shape of a sail.

BACKGROUND OF THE INVENTION

Sails are used to propel craft such as sailing vessels, sailboards, wheeled land sailers and the like. The sails are airfoils which function like an airplane wing to create lift and drag force to propel the vessel. Sails are designed to have a desired shape and to maintain that shape through a range of wind speeds. It is also desirable for the sails to be lightweight and durable. In the past sails have been formed of panels of material such as canvas or Dacron. Current high-performance sails are formed by laminating load-bearing materials such as Kevlar, carbon fiber, or Vectran between layers of film such as Mylar. Despite the use of these techniques, it is frequently desirable to alter the shape of the sail for power or lift in accordance with the sailing angle or wind speed. Current controls include tensioning the tuff of a sail with a Cunningham, the foot of the sail with an outhaul, or changing the bend or shape of a mast supporting the sail. The Cunningham typically includes a ring which is spaced upwardly from the tack or clew of a sail and tensioning device such as a strap or line with a purchase which are pulled downwardly to move the eye toward the tack or clew to tension the luff of the sail. The bending of the mast flattens the mainsail by pulling the luff curve out of the sail making the sail much flatter. However, when the sail gets flat in the forward portion, the rear portion of the sail towards the leech falls off to the leeward side of the sail.

It would be desirable therefore to provide a sail control which would flatten the main without resulting in having the rear or exit of the sail fall off to leeward.

SUMMARY OF THE INVENTION

The invention relates to a sail control device on a sailboat, in particular for triangular sails having a head, tack and clew and a main body portion. The sail control device includes at least one flexible tensioning member which extends across the body of the sail and attaches to an after portion of the sail. The tensioning member is slidable along the body to change the shape of the after portion of the sail. One or more of the flexible members may be mounted to a batten pocket or leech. In the preferred embodiment, the at least one tensioning member is a plurality of flexible members radiating from the forward portion of the sail to the after portion of the sail. The plurality of flexible members are mounted in tubes which are affixed to the outer surface of the body of the sail. In another embodiment the tensioning members are sandwiched between outer layers of material forming the outer surfaces of a laminated sail. The forward ends of the tensioning members may be mounted to a Cunningham line. Movement of the Cunningham and tensioning lines results in a change of shape in the after portion of the sail.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a sail control device in place on a jib and main of a sailboat in accordance with the invention;

FIG. 2 is a perspective view of a mainsail taken from the cockpit of a sailboat showing the change in shape occurring when the sail control device is tensioned in accordance with the invention;

FIG. 3 is a cross-sectional view of a sail showing a line movable between outer layers of the sail;

FIG. 4 is a cross-sectional view of a sail showing a flexible member inside a tube which is positioned between outer layers of the sail;

FIG. 5 is a partial side view of a sail showing a line affixed to a leech tape of the after portion of the sail;

FIG. 6 is a side view of an after end of the line attached to a force spreading device affixed to the leech of the after portion of the sail in accordance with the invention;

FIG. 7 is a side view of a portion of a front part of the sail showing a Cunningham and tack;

FIG. 8 is a side view of a mainsail showing lines extending along the curvature of the sail;

FIG. 9 is an adjustment device for adjusting the individual lines in accordance with the invention;

FIG. 10 is a cross-sectional view of a mainsail showing a tensioning member mounted to an outer surface of a sail;

FIG. 11 is a cross-sectional view of a mainsail showing a tensioning member mounted within a sleeve; and

FIG. 12 is a cross-sectional view of laminated panels and a tensioning member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIG. 1, a sail control device 10 for a sailboat includes at least one tensioning member 12 which is attached to an after or rear portion 14 of the sail. When the tensioning member 12 is tensioned, the rear portion 14 of the sail adjacent a leech is flattened. The after portion 14 is tensioned to prevent the exit of the sail from falling off to leeward to improve the performance of the sailboat 16.

The sail control device 10 is shown in FIG. 1 on a mainsail 18 or jib 20 as shown in FIG. 1. However, the sail control device may be used on any triangular fore and aft sail such as a main, jib, or stay sail. However, the construction and operation will be discussed herein only with respect to the mainsail 18. The main sail 18 has a head 22, a tack 24 at a forward lower corner portion 26 of the mainsail, a clew 28 at the after portion of the foot of the sail, and a main body 30 with rear portion 14. The sail may also be provided with a Cunningham. The Cunningham is a device which places tension on a luff 32 of the sail. The Cunningham includes a line 34 which extends through a ring 36 mounted in the lower corner portion 26 of the sail slightly above the tack 24. One end of the line 34 is secured to a tack fitting or eye 38 on the mast as shown in FIG. 7. The sail may include battens. Battens are inserted into batten pockets 42 on the sail to stiffen the after portion 14 of the sail and to control the shape of the after portion 14 and leech 44 of the sail.

As best shown in FIG. 1, the sail control device 10 includes one or more tensioning members 12 of strong, lightweight, flexible material such as a yarn of Tarwon or Vectran. Each of the tensioning members has a forward end 12a, a rear end 12(a), and a middle portion 12b. One end 46 of each of the tensioning members 12 is attached to an after portion 14 of the sail such as the leech 44 or a batten pocket 42. If a plurality of tensioning members 12 are used, the tensioning members 12 radiate outwardly from a lower forward portion 12c of the sail at or adjacent the tack 24 such as the Cunningham ring 36 best shown in FIGS. 1 and 7. The tensioning members 12 may be mounted on the external surface of the body 30 of the sail as shown in FIGS. 10 and 11, or sandwiched between layers of film which form a molded sail or the panels of a laminate sail as shown in FIGS. 3 and 4.

When the tensioning members 12 extend across the outer surface of the sail, tensioning members are slidably mounted to the surface. As shown in FIG. 10, a tube 48 is secured to the outer surface 66 of the sail by an adhesive 49. The tube 48 has an inner diameter large enough to freely accept the tensioning member 14. Alternatively, the tensioning member 12 may be guided by a sleeve 68 of flexible material affixed to the outer surface 66 of the sail. The flexible members 14 may extend on a straight line to the after portion of the sail (as shown in FIG. 1) or aligned to follow the curvature of the sail along a great circle route (FIG. 11). Alternatively the tubes could be located on the sail to extend horizontally across the sail to the luff or vertically to the foot of the sail where the ends are attached to a strap which extends either along the leech or along the foot of the sail to the clew (not shown). Mounting the tensioning members 12 on the outer surface of the sail allows the system to be used after the sail has been manufactured or on sails which are woven, such as Dacron. The tensioning members 14 may be alternated on opposing sides of the sail.

As shown in FIG. 5, an after end 43 of the tension member is secured to a suitable part of the after portion of the sail such as a leech tape 44 or batten pocket 42. When using the device on large sails, it may be necessary to use a patch 45 or other device to spread the load along the after portion of the sail as shown in FIG. 6. The face spreading patch 45 is sewn to the leech tape 44 and the after end of the tensioning member 12 is sewn to the strap 45. It may also be desirable to attach several spaced apart tensioning members 12 to a single batten pocket to assist in shaping the batten. In some cases it may be desirable to adjust the length of the tensioning member at the point where it is affixed to the after portion of the sail. A cam cleat or hook and ball arrangement can be used to permit the length of the tensioning member to be adjusted at the after end.

When used on a laminate sail, the tensioning members 12 may be sandwiched between the layers of the laminate as shown in FIGS. 3 and 4. Laminate sails may be formed in one piece or of panels of laminate material which are sewn together as shown in FIG. 12. When the sail is laminated in one piece such as a North 3DL or North 3IL, the laminates of these sails include a load bearing inner substrate of strands or monofilaments 50 of Kevlar, carbon fiber, Tarwon, or Vectran. The monofilaments 50 may be aligned along the force lines of the sail. The monofilaments are sandwiched between a pair of outer layers 52 of a plastic film such as Mylar and adhesive 54 (FIGS. 3 and 4). As shown in FIG. 3, the tensioning member 12 may be mounted in a passage 55 formed in the laminate void of any adhesive 54. Alternatively, the tensioning member 12 may be mounted in a tube 48 which is sandwiched between the outer layers 52 of the sail as shown in FIG. 4. The tube 48 has an inner diameter which is large enough to allow the tensioning member 12 to move freely within. In such construction the tube 48 is positioned with the fibers of the substrate in a mold and then covered with outer layers 52 and bonded as part of the sail during the sail forming and molding process.

As shown in FIG. 12, when the sail is formed of panels 64 of laminate material, the tube 54 is bonded within the outer layer 52 of film. The lead line is used to fish the tensioning member 12 through tubes 48 after the panels have been assembled and sewn together. After the panels 64 are cut to size, each end of the tube 48 is brought through a slit or opening 72 in the outer layer 52 a distance from the edge of the panel 64 near a tape 56 that is used to form the seam. After the panels 64 have been sewn or glued together, the tensioning member 14 is fished through the tubes in the panels. The tensioning member 14 passes over the seam or tape 56 where the tubes 48 exit the opening 72 as shown in FIG. 12 and then returns into the tube 48 of the next panel 64.

As shown in FIG. 7, forward ends 58 of the tensioning members are bundled in a stop device and attached to a line such as the Cunningham line 34. When the Cunningham line 34 is tightened, all of the tensioning members are also pulled to change the shape of the after portion 14 of the sail. The tensioning members 12 may be affixed to a dedicated line for pulling, so that adjustment can be made separate from the Cunningham (not shown). For large sails it may be desirable to have individual straps or cleats for each of the yarns so that the amount of tension for the individual lines can be adjusted from time to time. As shown in FIG. 9, the stop device is a series of cam cleats 60 or grippers may be mounted to a plate 62 so that the tension on each line can be adjusted so that the desired shape can be maintained. The lines may be color coded for easy identification of the associated part of the sail.

A visual scale may be placed at the clew for quick reference on the amount of Cunningham tension being placed on the tensioning lines.

Operation

When it is desired to adjust the depth of the sail, the Cunningham line 34 is tensioned pulling the lines through the tubes to flatten the sail in the area along the leech to prevent the exit of the sail from falling off. (See FIG. 2.) The after portion is moved from an untensioned position shown by dashed curvature lines 64, to a flattened position indicated by the dot-dot-dash lines 66. When the wind lightens or different point of sail is desired, the Cunningham strap is released to permit the lines to be eased and to permit a fuller shape in the sail at the midleech and exit positions. The control acts like a flap on an airplane wing which is positioned downwardly at takeoff to create increased drag and increased lift for takeoff and then straightened to reduce the drag to permit faster flight. This also to sail maker to design and make a sail with less lull curve and add to the roach of the sail. This elongates the working sail plan and generates more power. The sail changes from high lift to low drag shape without bending the mast. Consistent mast bend means a consistent slot permitting more jib in hauler or sheet to be applied. The sail is easier to trim. One simple element controls the sail depth.

Thus disclosed is an easy sail control which may be used to flatten the after portion of a sail. One skilled in the art will recognize variations and alternatives which are within the scope of the invention.

Claims

1. A sail shape control device for a sail having a forward portion adjacent a tack, a body portion, and an after portion, said control device including at least one flexible tensioning member extending from the forward portion along the body portion to said after portion, said flexible member movably attached to said body of said sail, said at least one tensioning member slidable with respect to the sail to change the shape of the after portion of the sail.

2. The sail control device of claim I wherein the at least one tensioning member comprises a plurality of flexible members radiating apart from the forward portion of the sail to the after portion.

3. The sail control device of claim 1 wherein said at least one tensioning member is mounted to an exterior surface of the sail.

4. The sail control device of claim I wherein the at least one tensioning member is sandwiched between outer surface layers of the sail.

5. The sail control device of claim 1 wherein each of the tensioning members extends through a tube.

6. The sail control member of claim 1 wherein one end of the tensioning member is fixed to a Cunningham line.

7. The sail control member of claim 2 wherein each of the plurality of tensioning members is independently adjustable.

8. The sail control device of claim 2 wherein at least one of said plurality of tensioning members is attached to a batten pocket.

9. The sail control device of claim 1 further comprising a tension adjuster.

10. The sail control device of claim 9 wherein the tension adjuster includes a stop device for each of said tensioning members.

11. A sail control device for a sail having a Cunningham ring, a body, and an after portion, said sail control device comprising:

a plurality of flexible tensioning lines having a forward end and an after end, said forward end of each of said tensioning lines attached extending from the Cunningham along the body of the sail, said tensioning members having a middle portion attached to the body of the sail, each of the after ends of each of the tensioning members being affixed to the after portion of the sail.

12. The sail control member of claim 11 wherein one end of the tensioning member is fixed to a Cunningham line.

13. The sail control device of claim 11 wherein said at least one tensioning member is mounted to an exterior surface of the sail.

14. The sail control device of claim 11 wherein the at least one tensioning member is sandwiched between outer surface layers of the sail.

15. The sail control member of claim 12 wherein each of the plurality of tensioning members is independently adjustable.