reference will now be made to the drawings wherein like structures will be provided with like reference designations . a first preferred embodiment of the inducer for sailboard or windsurf applications is shown in fig1 . inducer 10 has a body 12 to contain and connect all other structures . body 12 contains a first batten receptacle 16 for the right batten of a batten pair , and a second batten receptacle 18 for the left batten . batten receptacles 16 and 18 are positioned so that battens exit at a diverging angle from the aft of body 12 . batten receptacles 12 and 18 position the battens so the forward sail portions diverge as shown in fig2 and 3 . body 12 provides a structure to handle the leverage forces between right and left battens 52 and 54 . at the forward end of body 12 , there is a crescent shaped surface 102 for resting against the round mast of a windsurf sail rig . referring now to fig3 when inducer 10 is resting against mast 32 , a smooth surface is formed by the forward part of the sail as it wraps around mast 32 and the outer walls of receptacles 16 and 18 . referring again to fig1 inducer 10 has an optional slot 17 in the outward surface of receptacles 16 and 18 . slot 17 is provided to accept a portion of the batten pocket into receptacle 16 and 18 to aid in the insertion of battens , and to help hold the inducer in position while rigging the sail . it is to be understood that there are numerous other ways of holding inducer 10 in position such as hook and loop fasteners , buttons , tabs , clamps or rivets . batten receptacles 16 and 18 can be elongated vertically to allow for angling battens up or down from inducer 10 . optionally , surface 102 can be constructed of a thin flexible layer and connected to body 12 only at the outer edges . such a construction will allow surface 102 to conform to a variety of mast diameters . surface 102 can optionally be elongated vertically for better mast support . fig2 and 3 show a windsurf sail rig incorporating the camber inducer of the present invention to make a wing sail . a standard windsurf mast and boom are used in this embodiment . fig3 also shows the alternate position 144 for reversing the tack of the sail . the disadvantages of enclosing the mast do not apply to windsurf rigs . it is customary in windsurf art to enclose the mast with the sail . windsurf sails are relatively small and are rigged with the sail lying on the beach where the sailor has easy access to the entire sail . masts are of sufficient strength , usually being constructed with graphite and fiberglass composites . the sail consists of a right sail portion 48 , and a left sail portion 50 . the right and left sail portions 48 and 50 , are mirror images of each other and are connected in the luff area to form a continuous sail around the front of the mast . the mast clamp 142 clamps onto the mast 32 through a hole in the sail ( not shown ) as is customary in the art . a zipper 122 is sewn into the sail just to the side of the mast to provide access to the sail interior for inserting the forward batten ends into receptacles 16 and 18 . the right and left sail portions 48 and 50 have multiple pairs of adjacent batten pockets 56 and 58 sewn into the inner surface of the sail . the batten pockets extend horizontally from luff to leach except for a small gap or window 60 near the leach , as shown best in fig5 . batten pockets 56 and 58 are preferably made from a folded strip of sail cloth and sewn to the inside of the sail with a single row of stitching . each batten pocket 56 and 58 has a batten tensioning means at the trailing edge or leach of the sail as is typical in the art . a strap 64 and buckle 66 function as one preferred batten tensioning means . referring again to fig2 an inducer 10 is mounted at the forward or luff end of each pair of batten pockets 56 and 58 . battens are inserted through the right and left batten pockets 56 and 58 and into inducer batten receptacles 16 and 18 of each inducer 10 . a typical sail will have several batten pairs with inducers . the angle of the batten receptacles cause the inserted battens to arch away from each other at the luff of the sail . the arching pair of battens and their sails are brought together near the leach of the sail by a sliding hook 28 shown in detail in fig5 . and 6 . sliding hook 28 connects to the right and left battens through an opening or sliding hook window 60 on the inner surface of each batten pocket 56 and 58 . sliding hook 28 allows the rear portion of the sails to be held in slidable contact with each other . the length of sliding hook window 60 can additionally be used to limit the relative fore and aft movement of the trailing edge portions of the sail , which affects sail shaping . referring to fig2 and 3 , standard rigging is preferably used at the foot and head of the sail for tensioning the sail . the leach or trailing edge of the sail is tensioned with conventional rigging connected to an equalizing block 74 . equalizing block 74 is connected to the rear of the two sail surfaces 48 and 50 with an equalizing line 68 . equalizing line 68 runs through equalizing block 74 with one end connected to right sail 48 and one end connected to left sail 50 . equalizing block 74 allows the tensioning force applied from the boom to be applied equally to booth right and left sails 48 and 50 . block 74 applies this force to the sail through line 68 without interfering with the relative fore and aft movement of right and left sail portions 48 and 50 . the tensioning forces in line 68 are also separated by the diameter of block 74 which minimizes the likelihood of the sails catching on each other as they move fore and aft . referring to fig4 a to 4e , batten 21 for the preferred inducer embodiment has a less flexible portion 22 at the forward end , and a more flexible portion 24 in the mid forward section . mid less flexible portion 25 of the batten is also less flexible , and comprises the major portion of the batten . a more flexible aft flexible section 26 at the aft end of each batten aids in maintaining a smooth transitioning sail surface as the two sail portions 48 and 50 come into slidable contact with each other . controlling the flexibility of the batten in this way is employed to assist the inducer in achieving the optimum airfoil shape . the less flexible portion 22 at the front of the batten is necessary to overcome wind resistance and sail shaping forces as it holds the forward sail portions apart from each other . when a batten pair is in use with inducer 10 , the leeward batten forms the high arch of the airfoil as with batten 52 in fig3 . the more flexible portion 24 allows the leeward batten to curve from a divergent direction and to bend back toward the other batten at the trailing edge . the mid less flexible portion 25 is then used to hold a consistent shape for both the windward and leeward battens in the aft part of the sail continuing back to the trailing edge . the aft flexible section 26 at the trailing end of the batten allows the two battens to converge smoothly as they are brought together by sliding hook 28 . batten construction can be accomplished with methods known to one skilled in the art . the flexibility of the battens can be controlled with a variety of methods such as varying the batten thickness , shape , and materials of construction . materials such as fiberglass , graphite , and foam are common . fig4 a to 4e show an example of using cross section and shape of construction to control flexibility . cross section 4b has a less flexible solid portion for section 22 . a flattened solid cross cross section at 4c provides for the more flexible section 24 . a tubular batten at station m provides a lightweight , rigid middle portion for section 25 . section 26 also has a flat cross section shown at cross section 4e . referring to fig5 and 6 , one preferred embodiment of sliding hook 28 has a closed ring 30 , and a flexible hook section 29 . the flexible hook section is to provide a way to easily connect and disconnect one batten at sliding hook window 60 . sliding hook 28 holds the aft portions of the right and left battens of a batten pair in close proximity , while allowing easy fore and aft shifting of the battens . sliding hook 28 also allows some limited vertical movement of the right and left sails by virtue of it &# 39 ; s dimensions . this vertical movement can be used to assist and / or limit the sail shaping characteristics . another preferred embodiment for sliding hook 28 is to construct it with a flexible strap such as polyester webbing . the windsurf / sailboard embodiment does not need an opening and closing hook method and could easily incorporate this embodiment . however , if a reclosable hook for the strap is desired , there are a variety of possibilities . a connecting means such as hook and loop or tab and slot fasteners could be used to connect the ends of the strap . the wing sail of this first embodiment relies largely on wind pressure during sailing to hold the sail in the desired sail position at either tack . the positive pressure on the windward side of the sail in combination with the negative pressure on the leeward side of the sail is used to push the leeward batten into the desired high cambered arch shown in fig3 . the positive pressure of the wind on the windward side presses on the windward sail and batten . the pressure or leverage from the windward batten is transferred to the inducer body , and the inducer body presses the leeward batten outward to create the desired high camber in the leeward sail . the negative pressure caused by the airflow on the leeward side of the sail assists in creating the sail shape by pulling the leeward sail and batten outward . reversing tack is done as is customary in windsurf art . a sharp pull on the boom from the new windward side of the sail will reverse the sail camber , and the leverage of the windward and leeward battens in combination with the inducer will again create the designed airfoil shape . fig7 shows inducer 10t , a second preferred embodiment for my inducer . this embodiment has the same body 12 , a first batten receptacle 16 for the right batten of a batten pair , and a second batten receptacle 18 for the left batten . however , there is a modified mast interface . in addition to curved surface 102 to fit against a round mast , there are two slots 150 in curved surface 102 . slots 150 receive tabs 152 which are connected to a backing layer 154 . layer 154 is connected to mast 32 with adhesive or other means . referring to fig8 a and 9a , inducer 10t is preferably used in combination with a method to rotate all inducers in the sail by rotating the mast . a first preferred embodiment of my mast rotator 128 is shown in fig8 a and 9a . mast 32 is connected to boom 78 by mast rotator 128 . rotator housing 130 is connected to the forward ends of boom 78 replacing standard mast clamp 142 ( fig3 ). rotation arm 36 is pivotally connected to body 130 at housing pivot 135 . the other end of rotation arm 36 has a mast clamp 140 which securely holds mast 32 so it cannot slip or rotate in clamp 142 . a spring arm 132 is connected to body 130 at pivot 136 and to rotation arm 36 at pivot 134 . spring arm 132 can compress and expand while transmitting spring pressure to rotation arm 36 . referring again to fig8 a and 9a , a rotation force is applied to mast 32 by arm 36 pivoting on pivot 135 . the rotation of mast 32 , in combination with inducer 10t , and battens 52 and 54 , form the desired airfoil shape for the sail as shown in fig9 a . the rotated position is maintained to one side or the other by spring arm 132 . a change in tack is accomplished with a sharp pull on the boom from the new windward side . the positive and negative wind forces on the sail overcome the resistance of spring arm 132 , and arm 36 rotates to the opposite side . with the change in tack , the sail assumes the alternate airfoil position 146 shown in fig9 a . as an optional aid to rigging the sail , housing 130 and arm 36 can have holes ( not shown ) which line up when arm 36 is centered . a pin ( not shown ) can be inserted into the holes which will aid in rigging the sail by holding the mast and inducers centered in a neutral position for inserting and tensioning battens . two piece masts are common in windsurf art . when a two piece mast ( not shown ) is used , the rotational forces on mast 32 caused by mast clamp 140 and rotation arm 36 need to be transferred to the top portion of the mast . this can be accomplished by drilling a small hole in the overlapping joint of the mast ( not shown ) and inserting a small pin ( not shown ) through both mast portions and installing a keeper ring ( also not shown ) to hold the pin in place . fig8 b and 9b show mast rotator 128a , a second preferred embodiment for my mast rotator . in mast rotator 128a , body 130a is connected to the forward end of boom 78 . a portion of housing 130a extends around mast 32 to form a sleeve 142 . mast clamp 140a encircles and securely holds mast 32 just inside sleeve 142 . mast clamp 140a serves as a bearing surface between mast 32 and sleeve 142 allowing mast 32 to rotate inside of sleeve 142 . referring again to fig8 b and 9b , arm 36a extends into housing 130a from mast clamp 140a . spring arm 132a is pivotally connected to rotation arm 36a at pivot 134a and to housing 130a at housing pivot 136a . spring arm 132a exerts a force on arm 36a that helps maintain mast 32 in a rotated position by holding arm 36a on either side of housing 130a to hold the sail and battens in the desired airfoil shape on either tack . a third embodiment of my rotator ( not shown ) is preferably used with inducer 10t and is similar to the second embodiment shown in fig8 b and 9b . the third rotator embodiment consists of housing 130a to connect boom 78 to mast 32 . housing 130a comprises a sleeve 142 which surrounds mast 32 . a mast clamp similar to clamp 140a serves as a bearing surface and to keep sleeve 142 from sliding up or down mast 32 . sleeve 142 and the mast clamp allow mast 32 to rotate freely within the housing 130a . this third rotator embodiment relies on wind pressure to hold the sail in the desired shape on either tack . fig1 a and 10b show detail of inducer 10t fitting different diameter masts . the typical windsurf mast is tapered , and so for an inducer to be used at different heights on a mast , it must be able to fit different mast diameters . fig1 a shows inducer 10t and tab backing 154 accommodating a small diameter portion of mast 32 . fig1 b shows inducer 10t and tab backing 154 accommodating a large diameter portion of mast 32 . the tab and slot method of connecting inducer 10t to mast 32 allows inducer 10t to slide vertically on mast 32 as the sail is assembled and tensioned . vertically sliding inducer 10t also allows the same mast and set of inducers to be used for several different sized sails which will all have different batten spacing . there are numerous other methods of interfacing my inducer with the sail or mast of a windsurf rig including various clamps , tabs , pins and the like . two such alternate embodiments are shown in fig1 , 12 , and 13 . fig1 shows a modified tab 152a on backing 154 , and a modified slot 150a in body 12 . fig1 shows a single &# 34 ; t &# 34 ; shaped track or tab 152b on backing 154 , and a single slot 150b in body 12 for receiving track 152b . fig1 shows inducer 10a with a cutout 100 just aft of surface 102 . screw clamp 96 passes through body 12 at cutout 100 and exits the sides of body 12 . clamp 96 provides a means to connect inducer 10a to windsurf mast 32 . in still another embodiment of inducer 10 ( not shown ) surface 102 can also be made flexible so it will fit against the various diameters of the typical tapered windsurf mast 32 . fig1 shows another preferred embodiment of my inducer . inducer 10j can be easily applied to a jib , the front sail of a sailboat . inducer 10j has a body 12j , and two clamping plates 14 . body 12j is generally v shaped . in use , the apex of the v points forward into the wind . body 12j has structure to withstand and transfer the leverage forces caused by right and left battens 52 and 54 ( fig3 ). body 12j has batten receptacles 16j and 18j at opposite sides of the v . batten receptacles 16j and 18j become enclosed on the sides when plates 14 are connected in place with connecting holes 20 and rivets one of which is shown in fig1 at 15 . referring to fig1 and 16 , inducer 10j is designed to be used with a double surfaced sail . such a sail is shown in fig1 and 16 . the double surfaced jib is like sewing two jibs together at the luff to form right sail 48j and left sail 50j . as is customary in the art , the jib has a loop of cloth at the luff which surrounds a supporting cable 38 to hold the forward portion of the jib in place . a halyard 39 is connected to the top of jib 82 to raise and tension the sail as is customary in the art . referring still to fig1 and 16 , inducer body 12j is positioned between the right sail 48j and left sail 50j , of a double surfaced jib just behind the stitching 49j connecting the two sail portions together . clamping plates 14 are positioned on the outer surfaces of right and left sails 48j and 50j to clamp the sail portions against body 12j . rivets 15 extend through clamping plate 14 , sail 48j or sail 50j , and connector body 12j to clamp all three together . right and left batten receptacles 16j , and 18j are formed by the connection of clamping plates 14 on each side of inducer body 12j . the forward end of each batten pocket 56 and 58 is also sandwiched between inducer body 12j and clamping plate 14 . the forward end of each batten pocket 56 and 58 is positioned inside it &# 39 ; s respective receptacle 16 and 18 . when batten 52 is inserted into pocket 56 , the forward end of batten 52 is guided into receptacle 16 . fig1 shows a jib as it would appear in use on a sailboat . left sail 50j is the windward sail , right sail 48j is the leeward sail . the wind creates positive pressure on the windward sail 50j . the windward sail 50j presses on left battens 54 . the forward batten portion presses on inducer 10j . inducer 10j presses outward on leeward right batten 52 . this outward pressure helps to create the high cambered shape in leeward sail 48j . the leeward sail and associated battens also assist in sail shaping by virtue of the lift created by the sail . the negative pressure caused by the lift of leeward sail surface 48j pulls the leeward sail and batten outward which transfers force through inducer 10 to help flatten the windward sail surface 50j . equalizing block 74j applies a balanced force to both right and left sail portions 48j and 50j from the jib sheet line 84 . block 74j allows right and left sails 48j and 50j to shift position upon changing tack . conventional methods of sail trimming can be used on a jib utilizing my invention . fig1 shows a main sail of a sailboat incorporating my invention . sailboats without a rotatable mast will use inducer 10j . sailboats with a rotatable mast will use inducer 10m shown in detail in fig1 and 19 . one preferred embodiment of the inducer is shown in fig1 and 19 . inducer 10m has a body 12m , and two clamping plates 14m . each clamping plate 14m has a leverage arm 11 . the body 12m is generally v - shaped . in use , the apex of the v points forward toward the mast . as shown in fig1 and 19 , inducer body 12m is positioned between the right sail 48m and left sail 50m , just behind the luff rope stitching 49m of the sail . clamping plates 14m are positioned on the outer surface of the right and left sail 48m and 50m . the forward end of each batten pocket is sandwiched between inducer body 12m and clamping plate 14m . rivets 15 extend through clamping plate 14m , sail 48m , and body 12m to clamp all three together . right and left batten receptacles 16m , and 18m are formed by the connection of clamping plate 14m and inducer body 12m . leverage arm 11 extends from the outer surface of clamping plate 14m . the forward ends of lever arms 11 extend forward to be in close proximity to supporting mast 32m . constructing clamping plate 14m and leverage arm 11 with plastic will reduce the friction against mast 32m and avoid marring mast 32m . referring to fig1 , inducer 10m has an optional reinforcing layer 13 that lays against the outer surface of right and left sail 48m and 50m ( fig1 ). reinforcing layer 13 extends forward from right sail 48m , around bolt rope 46 , and back to lie against the outside of left sail 50m . reinforcing layer 13 is held in place by clamping plates 14m and connecting rivets 15 . reinforcing layer 13 is designed to help take the stress on the sail caused by the leverage between leverage arm 11 and bolt rope 46 in mast groove 34 . traditional trimming methods can be used in a main sail incorporating my camber inducer . referring to fig1 , the sail consists of a right sail portion 48m , and a left sail portion 50m . the right and left sail portions 48m and 50m are mirror images of each other connected only at a common headboard ( not shown ) and bolt rope . the bolt rope is designed to be retained by mast groove 34 , as is customary in the art . the sail can alternatively use sail slides or sail slugs ( not shown ) to connect to mast groove 34 . the sail also has a conventional headboard ( not shown ) at the head of the sail for connecting to a halyard line ( not shown ) for raising and lowering the sail . a conventional downhaul connection ( also not shown ) is located at the foot of the sail to tension the luff of the sail as is customary in the art . each sail portion has multiple full length battens carried by batten pockets 56 and 58m sewn to the inside surface of right and left sail 48m and 50m . referring again to fig1 , the right and left sail batten pockets 56m and 58m form adjacent pairs . the batten pockets 56m , and 58m extend from leach to luff except for a small gap or window 60 near the leach . each batten pocket has a batten tensioning means at the trailing edge or leach of the sail as is typical in the art . strap 64 and buckle 66 are shown in this embodiment . referring to fig1 and 19 , inducer 10m , is mounted at the forward or luff end of each pair of batten pockets . body 12m is positioned inside the two sail portions 48m and 50m at the luff . plates 14m are positioned on the outside sail surfaces to clamp sails 48m and 50m between body 12m and plate 14m . the forward end of each batten pocket is sandwiched by the inducer clamping plate 14m on the outside of the sail , and the inducer body 12m on the inside of the sail forming batten receptacles 16m and 18m . referring again to fig1 and 19 , battens are inserted into batten pockets 56m and 58m at the leach and are guided into batten receptacles 16m and 18m of inducer 10m . the angle of the batten receptacles 16m and 18m cause the battens to arch away from each other at the luff of the sail . the arching pair of battens and their sails are brought together near the leach of the sail by sliding hook 28 . sliding hook 28 connects to right and left battens 52 and 54 through sliding hook window 60 on the inner surface of each sail . sliding hook 28 allows the rear portion of the sails to be held in slidable contact with each other . a clew plate assembly is shown in fig1 and 20 . each clew plate assembly consists of an outer clew plate 73 and inner clew plate 71 . sail portions 48m , and 50m are sandwiched between the outer and inner plates 73 and 71 . outer plate 73 has a knot extension 76 , with a hole for connecting line 68m . line 68m is retained in the outer plate with a knot such as a figure eight knot . line 68m runs from the knot extension 76 of right clew plate 70 , downward through equalizing block 74m and back to knot extension 76 of left clew plate 72 where it is secured with a second figure eight knot . line is one preferred connector means because it is strong , light , flexible , inexpensive , and easy to replace when it gets worn . line 68 can also be constructed from steel cable and connected with pins or shackles . clew plate 70 and 72 are constructed of traditional materials such as aluminum , and use common mounting methods such as rivets . referring again to fig1 and 20 . equalizing block 74m is constructed from two aluminum plates which sandwich two small sheaves 79 . a swivel attachment 81 provides for connection to boom 78m with a conventional shackle . equalizing block 74m is able to rotate about its mounting point on the boom by virtue of swivel 81 . equalizing block 74m allows the sheeting force applied to the boom with main sheet 80 to be applied equally to booth right and left sails 48m and 50m . block 74m applies this force to the sail through line 68m without interfering with the relative fore and aft movement of right and left sail portions 48m and 50m . the downward sheeting forces are separated by the distance between sheaves 79 . thus , both right and left sails 48m and 50m have a vertical or nearly vertical sheeting force applied . the distance between sheaves 79 is appropriate for the fore and aft movement of right and left sails 48m and 50m . as right and left clew plates 70 and 72 are shifting fore and aft ( as when changing tack ), equalizing block 74m serves as a cam to separate the right and left plate assembly 70 and 72 . the camming action is shown by a cam action arrow 77 in fig2 . camming action 77 stops the two plates from catching on each other as they pass each other in their respective fore and aft movement when changing tack . referring to fig1 , a conventional boom 78m is connected to mast 32m with conventional connection means ( not shown ). boom 78m is able to pivot in relation to the mast 32m . a conventional main sheet line 80 is connected to the boom 78m . referring to fig1 and 19 , a conventional mast is used in this embodiment . mast 32m has a mast groove 34 which retains bolt rope 46 ( fig1 ) of the sail . mast 32m also has customary means to raise and lower the sail ( not shown ). mast 32m is preferably a rotatable mast for use of inducer 10m . a non rotatable mast would require the use of inducer 10j . referring to fig1 , rotation arm 36m is mounted on mast 32m near boom 78m . outward ends of arm 36m extend slightly forward of mast 32m . rotation arm 36m is only applicable to rotatable mast embodiments . lines 38 pass from the outward ends of the rotation arm 36m , and connect to the boom with block 40 . blocks 40 are used as necessary for the appropriate mechanical advantage to induce a rotation in mast 32m . each rotation arm line 38 has a cleat ( not shown ), for securing the line 38 at the desired rotation . lines 38 have one or more rotation line redirection blocks ( not shown ), to lead lines to the crew area , and to align line 38 for cleating . lines 38 lead to a point which is accessible by the crew for cleating and releasing the line . fig2 shows a third preferred embodiment for my inducer applied to a sailboat batten traveler car . a typical traveler car system is shown . as is common in the art , a track 86 is attached to mast 32m . a car 88 slides on track 86 . car 88 has a pivot connector 92 which inducer 10c is mounted to . pivot connector 92 can be designed to allow inducer 10c to pivot in two or three axis of rotation . referring again to fig2 , inducer 10c has a body 12m with recesses for batten receptacles 16m and 18m . right and left sail portions 48m and 50m are clamped against body 12m with right and left clamping plates 14c just as in the previous embodiment . plates 14c also form part of batten receptacles 18m and 16m . clamping plates 14c have a forward extending portions 98 which provide a connection means to connect to batten car 88 at pivot 92 . extensions 98 also form a recess 94 , which serves as a bolt rope retainer to clamp and hold bolt rope 46 of the sail . batten car 88 allows inducer 10c to pivot about a non rotating mast , while still positioning the opposing battens of a batten pair at the correct angle to form a double surfaced airfoil . such a sail can be flaked with both right and left battens inserted in inducers 10c or just one batten of each pair can be pulled out of its receptacle in order to flake or otherwise collapse the sail . plate 14c can additionally have a leverage arm like leverage arm 11 in fig1 for use with batten car 88 and a rotatable mast . such an arrangement would preserve the ease of raising and lowering the sail provided by batten car 88 and still have the positive control offered by a rotatable mast . referring to fig2 , an inducer 10s is shown . inducer 10s is similar to inducer 10c in fig2 , but 10s has a slide connector 156 sandwiched between forward extending portions 98 . slide connector 156 provides a connection for the bail portion of a sail slide ( not shown ) or a sail slug 90 . fig2 shows inducer body 12a demonstrating an alternate method of fabricating inducer parts . inducer body 12a is formed from a flat piece of aluminum . a channel 158 is formed in the plate which becomes receptacles 16a and 18a when body 12a is formed into a &# 34 ; v &# 34 ; shape . the deformation of the channel 158 closes the forward end of receptacles 16a and 18a and forms batten stop 160 , which stops the forward movement of right and left battens 52 and 54 . brace 162 is attached to each end of channel 158 to provide the structure necessary to hold battens 52 and 54 at the desired angle . fig2 a to 24c , demonstrate the sail shapes attainable with inducer 10m when used on a sailboat with a rotatable mast . the view is a top view showing the sail profiles . fig2 b show a neutral airfoil when the mast is not rotated in relation to the boom . 24a shows the sail profile resulting from when the mast is rotated in a clockwise direction in relation to the boom as would be the case for a starboard tack . fig2 c shows the mast rotated counter clockwise in relation to the boom , shaping the sail for a port tack . fig2 a to 25c show sail shapes attainable with inducer 10j and a non - rotatable mast . the view is once again a top view showing the sail profiles . fig2 a shows a neutral airfoil . this shape would result with the boat headed directly into the wind ( or with no wind at all ). fig2 b shows the sail shape if the boat is placed on a port tack . the wind is coming from the left , causing a positive wind pressure on left sail 50m and making it flatten out . as a result of this flattening , left batten 54 in left sail 50m presses on inducer 10j , causing inducer 10j to press outward on right batten 52 and right sail 48m . in addition , the wing shape and angle of attack cause a negative pressure on right sail 48m , which also helps to pull right sail 48m out , forming the arching camber shape of a wing . the batten characteristics are important because the more flexible portion 24 ( fig4 a ) is where the batten will bend to create the camber in the airfoil . fig2 c is an example of the sail shape resulting from the main sheet line 80 being traveled out and with the wind coming from the lower left as would be the case on a port reach . the sail is rotated in relation to the non - rotatable mast 32m and also in relation to the boat ( not shown ), but still forming an efficient wing shape . in view of the forgoing , it will be appreciated that the invention provides a batten retaining and positioning device which positions battens to form the sail into a double surfaced airfoil shape and the invention provides a camber inducer which can be adapted for this use on a windsurf sail or on a sailboat sail . the present invention also provides a method to assist in holding a mast rotation to assist the inducers in maintaining the desired wing sail shape . the present invention also provides a wing sail which is adaptable to both large and small craft and which can be mounted on a standard sail boat or sail board mast . the present invention further provides a wing sail with a reversible camber , providing an efficient wing shape on either tack and which allows the use of conventional mast rigging and methods of achieving mast support and rigidity . still further , the present invention provides a wing sail which can be raised , lowered , and stowed with relative ease like a standard fully battened sail , with fewer parts making it simple , reliable , and inexpensive . the present invention further provides a wing sail which allows the use of conventional sail trimming techniques for adjusting the sail shape to various wind conditions and craft needs . even further , the invention provides a clew connection which allows the two sail portions to shift while at the same time maintaining the desired sheeting forces and provides a mast rotation device to assist in shaping a wing sail . the present invention may be embodied in other specific forms without departing from its spirit or essential characteristics . the described embodiments are to be considered in all respects only as illustrative and not restrictive . the scope of the invention is , therefore , indicated by the appended claims rather than by the foregoing description . all changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope .