Abstract:
A method and apparatus for increasing sail efficiency is disclosed. The apparatus comprises a second sail, disposed in a second plane substantially perpendicular to the first plane, wherein the second sail is disposed proximate a periphery of the first sail.

Description:
[0001]     This application claims benefit of U.S. Provisional Patent Application No. 60/661,252, entitled “METHOD AND APPARATUS FOR INCREASING SAIL EFFICIENCY,” by Stephanie N. Cooper, filed Mar. 11, 2005, which application is hereby incorporated by reference herein. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to sailboats, and in particular to a system and method for improving the efficiency of the sails used on such sailboats.  
         [0004]     2. Description of the Related Art  
         [0005]     Sailing is a sport popular the world over. Many enthusiasts participate in sailboat races, where the difference between winning and losing can amount to mere seconds. Typically, the outcome of these races is determined by the skill of the captain and the crew to select the proper course, the best sail combination and to deploy the sails properly to best utilize the available wind. These factors are even important in non-competitive sailing, as they can have a substantial effect on the vessel&#39;s speed through the water.  
         [0006]     What is needed is an method and apparatus for increasing the efficiency of a sail. What is also needed is a means for deploying this efficiency-increasing apparatus. The present invention satisfies that need.  
       SUMMARY OF THE INVENTION  
       [0007]     To address the requirements described above, the present invention discloses a method and apparatus for increasing sail efficiency. The apparatus is typically for use with a first sail disposed in a first plane between a mast and a boom, and comprises a second sail, disposed in a second plane substantially perpendicular to the first plane, wherein the second sail is disposed proximate a periphery of the first sail. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     Referring now to the drawings in which like reference numbers represent corresponding parts throughout:  
         [0009]      FIG. 1A  is a diagram showing side view of an exemplary prior art sail deployed between a mast and a boom;  
         [0010]      FIG. 1B  is a diagram showing a top view of the sail shown in  FIG. 1A ;  
         [0011]      FIG. 2A  is a diagram showing a side view of one embodiment of the present invention;  
         [0012]      FIG. 2B  is a diagram showing a top view of the embodiment of the present invention illustrated in  FIG. 2A ;  
         [0013]      FIG. 2C  is a diagram showing a top view of another embodiment of the present invention;  
         [0014]      FIG. 3A  is a diagram showing a top view of a two-sided embodiment of the present invention in which the boomlet supporting the auxiliary sail is disposed proximate the mast;  
         [0015]      FIG. 3B  is a diagram showing the embodiment illustrated in  FIG. 3A  viewed from the perspective of location “A”;  
         [0016]      FIG. 4A  is a diagram showing a top view of another two-sided embodiment of the present invention in which the boomlet supporting the auxiliary sail is disposed distal from the mast;  
         [0017]      FIG. 4B  is a diagram showing the embodiment illustrated in  FIG. 4A  viewed from the perspective of location “B”;  
         [0018]      FIG. 5A  is a diagram showing a top view of a selectably deployable embodiment of the auxiliary sail and boomlet;  
         [0019]      FIG. 5B  is a diagram showing a rear view of a further embodiment of the auxiliary sail that is deployable to both sides of the main sail;  
         [0020]      FIG. 6A  is a diagram showing another embodiment of the present invention using a self-supporting auxiliary sail structure;  
         [0021]      FIG. 6B  is a diagram showing a top view of the embodiment illustrated in  FIG. 6A ;  
         [0022]      FIG. 7A  is a diagram showing an embodiment of the self-supporting auxiliary sail structure disposed proximate the base of the mast;  
         [0023]      FIG. 7B  is a diagram showing a top view of the embodiment illustrated in  FIG. 7A ;  
         [0024]      FIG. 8A  is a diagram showing an embodiment of the self-supporting auxiliary sail structure having an elongated shape; and  
         [0025]      FIG. 8B  is a diagram showing a top view of the embodiment illustrated in  FIG. 8A . 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0026]     In the following description, reference is made to the accompanying drawings which form a part hereof, and which is shown, by way of illustration, several embodiments of the present invention. It is understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention.  
         [0027]      FIGS. 1A and 1B  are diagrams illustrating a typical prior art sail system  100 . The sail system  100  comprises a mainsail  102 , which is held in place by a attachment to a mast  104  and a boom  106  whereby the boom is rotatable in a plane perpendicular to the mast  104 , allowing the mainsail  102  to be rotated about the mast  104  for optimal performance. The boom  106  is rotatably affixed to the mast  104  using a rotatable joint  110 , and is held in position in the vertical plane by boom cable  108 , which is attached to the top of the mast  104  and the end of the boom  106  distal from the mast  104 .  
         [0028]     The mainsail  102  can be affixed to the mast in a number of ways known in the art. For illustrative purposes, the mainsail  102  shown in  FIG. 1  is affixed to the mast  104  by use of attachment loops  112 , which typically slide along a track within the mast  104 . The mainsail  102  is affixed to the attachment loops  122  (for example, via grommets), thus attaching the mainsail  102  to the mast  104  in a way that permits the mainsail  102  to be stored by wrapping it around the boom, and deployed by use of a cable and pulley near the top of the mast  104 . The mainsail  102  is attached to the boom using similar techniques known in the art.  
         [0029]      FIG. 1C  is a diagram showing the spatial relationships that will be used to describe embodiments of the invention. The mast  104  is co-linear with the M axis  120 , and the boom  106  is collinear with the B axis  122 . The B axis  122  is perpendicular to the M axis  120 , and the mainsail  102  is disposed in first plane  134  which is defined by the M axis  120  and the B axis  122 . Axis B′  124  is perpendicular to both the M axis  120  and the B axis  122 . Axes B  122  and B′  124  define a second plane  132 , while axes M  120  and B′  124  define third plane  130 .  
         [0030]      FIGS. 2A-2C  are diagrams illustrating one embodiment of an improved sail system  200 . The improved sail system  200  (hereinafter alternatively referred to simply as the sail system  200 ) also comprises a mainsail  102  disposed (e.g. suspended) in a plane defined by the mast  104  and the boom  106  (e.g. the first plane  134  shown in  FIG. 1 ). Unlike the prior art sail system  100 , the illustrated sail system  200  includes a second sail  204  (hereinafter alternatively referred to in its various embodiments as the auxiliary sail  204 ).  
         [0031]     The second sail  204  is disposed in a plane that is perpendicular the plane  130  defined by the mast  104  and the boom  106  (i.e. any plane co-planar with plane  132 ). In the embodiment shown, the second sail  204  is suspended by connection to the boom  106  and a boomlet  202 . The second sail  204  can be connected to the boom and/or boomlet  202  by means known in the art, including via the use of grommets disposed in the second sail and/or tie down points  206 A- 206 C disposed on the boomlet  202  and the boom  106 . The second sail  204  serves to increase the efficiency of the mainsail  102  by directing the laminar airflow over the mainsail  102 .  
         [0032]     In  FIG. 2B , the second sail  204  is disposed on the windward side of the mainsail  102 . In  FIG. 2C , the second sail  204  is disposed on the leeward side of the mainsail  102 . To decrease wind resistance, the boomlet  202  may be made non-circular (e.g. ovoid, teardrop shaped) in cross section.  
         [0033]      FIGS. 3A and 3B  are diagrams illustrating another embodiment of the invention, in which the second sail  204  is disposed on both sides (leeward and windward) of the mainsail  102 . Again, in this embodiment, the second sail  204  is suspended by a boomlet  202 , but in this case, the boomlet  202  extends to both sides of the mainsail  102 . This embodiment further increases the efficiency of the mainsail  102  and provides essentially the same functionality regardless of the rotation of the boom about the mast. While  FIGS. 3A and 3B  illustrate the boomlet  202  disposed below the boom  104 , the boomlet  202  may be disposed anywhere as necessary to support the second sail  204  in a plane that is coplanar with plane  132   
         [0034]      FIGS. 4A and 4B  illustrate an embodiment similar to that which is illustrated in  FIGS. 3A and 3B , except the boomlet  202  is disposed distal from the mast  202  toward the stern of the craft. Also,  FIG. 4A  discloses an embodiment in which the boomlet  202  is coupled to the boom  106  via a rotatable joint  210 , thus permitting the second sail  204  to be easily deployed or undeployed by  90  degree rotation (of which an intermediate position is shown as  212 ). This rotatable boomlet option can also be implemented with the boomlet  202  adjacent the mast, with a pulley structure such as that which is described below.  
         [0035]      FIG. 5A  illustrates an embodiment in which the second sail  204  is deployable and stowable by use of a movable boomlet  202 . In the embodiment shown in  FIG. 5A , the boomlet  202  (shown in deployed position) can be disposed in a stowed position  202 ′. In this embodiment, the boomlet  202  rotates around an axis emerging perpendicularly from the drawing—that is—an axis parallel to the mast and perpendicular to the boom  106 —as shown. This is implemented by use of a joint  208  disposed at the end of the boomlet  202  closest to the boom  106 . Deployment of the boomlet  202  (and hence, the second sail  204 ) can be effected by tensioning the first cable  502 , and can be brought back to the stowed position  202 ′ via tensioning of the second cable  504 . This is accomplished by application of a pulley  506  rotating about an axis parallel to the mast  104 . In the illustrated embodiment, the pulley  506  rotates about an axis collinear with the mast  104 .  
         [0036]      FIG. 5B  illustrates another embodiment in which the second sail is deployable on opposite sides of the boom  106 . This is implemented with a joint  212  having an axis of rotation that is parallel to the boom  108 . The joint  212  or associated structures on member  210  and the boomlet  202  may include provision for affixing the boomlet  202  in first position  202 ″ or second position  202 ′″. Such provision may include interlocking structures on the boomlet  202  and the member  210 .  
         [0037]      FIGS. 6A and 6B  are diagrams of another embodiment of the present invention. In this embodiment, the second sail  602  is proximate the top of the mast  104 , improving airflow over the upper region of the mainsail  102 . Also, in this embodiment, the second sail  602  is constructed of a shape-retaining material such as a plastic, so that structures such as the boomlet  202  are not required.  
         [0038]     The second sail  602  can be affixed to the mast  104  with a rotatable joint  604  such that the second sail  602  can rotate about the mast  104  axis, or may be fixed to the mast  104 . The rotatable joint  604  can allow the second sail  602  to always point into the wind, regardless of the boom  106  position, or may rotate along with the boom  106 , possibly by affixation to the boom cable  108 . Although the second sail  602  shown in  FIGS. 6A and 6B  is wing-shaped, other shapes can also be used.  
         [0039]      FIGS. 7A and 7B  are diagrams showing an embodiment of the present invention wherein the second sail  602  is affixed to the mast proximate the boom  106 . As was the case with the embodiment shown in  FIGS. 6A and 6B , the second sail  602  may be rotatable about the mast or non-rotatable. The second sail  602  may be made to rotate with the boom  106  via appropriate affixment to the boom  106 .  
         [0040]      FIG. 8A and 8B  are diagrams showing another embodiment of the present invention. In this embodiment, the second sail  802  (which may also be constructed of a shape-retaining material) extends a greater distance along the boom  106  to provide increased influence over the airflow over the mainsail  102 . In the illustrated embodiment, the second sail  802  is also teardrop shaped when viewed from above.  
       CONCLUSION  
       [0041]     This concludes the description of the preferred embodiments of the present invention. The foregoing description of the preferred embodiment of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. For example, although the embodiments disclosed above illustrate the use of the second sail either above or below the mainsail, it is also envisioned that a second sail can be placed in both locations. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto. The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.