Abstract:
A wind-propelled vehicle, particularly a multi-hulled sailing vessel, in which instead of mast, the upper spar ( 14 ) of the sail ( 13 ) is supported from a carrier ( 13 ) which moves athwart the vessel in a track in the form of an arch ( 16 ).

Description:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0001]    Not applicable.  
         REFERENCE TO MICROFICHE APPENDIX  
         [0002]    Not applicable.  
         FIELD OF THE INVENTION  
         [0003]    This invention relates to sail-powered vessels or vehicles. Although it is of general applicability, the invention has particular application to catamarans and other multi-hulled vessels, and will be particularly described by reference to its application to a catamaran.  
           [0004]    An object of the invention is to provide a method of supporting a sail of the “crab claw” type, such that the limitations of known methods of rigging such sails are to a useful extent avoided.  
         BACKGROUND OF THE INVENTION  
         [0005]    The crab claw sail has been known since the ancient Polynesians. In its common form it consists of a triangular sail suspended between an upper and a lower spar, the spars converging towards the forward end of the sail where the sail is fixed in the region of the bow. The top spar is attached to a mast with the sail on the leeward side of the mast, and the bottom spar is attached to the hull.  
           [0006]    Such a sail configuration is difficult to tack. Because the sail must be located on the leeward side of the mast, in tacking the sail must be lowered and moved to the other side of the mast, then raised again. The sail is furthermore difficult to reef.  
         BRIEF SUMMARY OF THE INVENTION  
         [0007]    In accordance with the present invention, the upper spar of the sail is supported by means including a support device capable of movement athwart the vessel. The support device may, in one possible embodiment of the invention, take the form of a moveable support mounted to travel athwart the vessel on a track. The path of the support device may be arcuate, in which case the track referred to may be configured in an arc extending across the vessel. (In this context it is not intended by the use of the word “arc,” that the arc must be part of a circle. For example, it may be elliptical or formed by merging two or more curves.)  
           [0008]    Broadly, therefore, the invention resides in a wind-propelled vehicle having a rigging of the crab-claw type, the vehicle including a sail having an upper spar and a lower spar, characterized in that the sail is supported by the connection of the upper spar to means capable of movement athwart the vehicle. Preferably the support means includes a moveable support mounted to travel athwart the vessel on a track, and preferably the track is configured in an arc extending across the vessel. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0009]    An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:  
         [0010]    [0010]FIG. 1 is a side elevation of a catamaran embodying the invention.  
         [0011]    [0011]FIG. 2 is an end elevation of the catamaran of FIG. 1 from the bow.  
         [0012]    FIGS.  3 - 5  show details of a carrier.  
         [0013]    [0013]FIG. 6 shows in side elevation an arch mounting arrangement, and  
         [0014]    [0014]FIG. 7 is an end elevation of the arrangement shown in FIG. 6. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0015]    The illustrated catamaran includes a pair of hulls  10 , a deck  11  and superstructure  12 , and carries a crab claw sail  13  with top spar  14  and bottom spar  15 . In accordance with the invention, the vessel does not have a mast but rather the sail is supported by means of a structure which in this embodiment takes the form of an arch  16  the feet of which are mounted on either side of the deck.  
         [0016]    Mounted on the arch  16  for movement around the arch is a carrier  17 , supporting a block (not shown) which supports the top spar  14 . The lower spar  15  is restrained by a sheet  19  fixed to a carrier running in a track fixed across the deck or superstructure, in the region of the plane of the arch. The longitudinal position of the sail relative to the arch is such that the fore and aft portions of the sail are substantially balanced. As well as allowing for simple control of the sail, this allows gentle gybing.  
         [0017]    The arch  16  in this embodiment consists of a pair of tubular rails  20  interconnected by a cross-bracing lattice structure  21 . The feet of the arch are supported on the deck of the catamaran and guided by rails  22 , as will be described in more detail below.  
         [0018]    FIGS.  3 - 5  show the carrier  17  in more detail. It will be seen to include a box-like frame  23  which embraces the arch, with upper, lower and outside wheels  24 , 25 ,  26  which engage the side rails  20  of the arch to support and guide the carrier. Each of the wheels may be mounted by means of an axle  27  fixed in place by a pair of U-bolts  28 .  
         [0019]    A centrally located stiffening flange  29  is provided on the lower surface of the carrier  17 , for the support of a block (not shown) from which the upper spar  14  is suspended. The upper wall of the carrier is provided with a pair of flanges  30  which provide anchoring for a pair of ropes (not shown) which pass downwardly over the arch towards the deck for movement of the carrier around the arch.  
         [0020]    While the arch  16  can be fixedly mounted to the deck, it is preferred that it be mounted in such as way as to allow a certain amount of fore-and-aft movement, and also pivoting movement. FIGS. 6 and 7 illustrate one way of achieving this.  
         [0021]    A pair of flanged rails  22  are fixed to the deck on each side of the vessel, and the feet of the arch are supported on runners  32 , which rest on wheels  33  which can roll along the deck, trapped between the deck and the flange  34  of the rail  22 . The wheels  33  run on axles fixed to the outer flanges  35   a  of the runners  32 , which also have inner flanges  35   b  located inboard of the rails  22 .  
         [0022]    The fore and aft position of the arch is fixed by means of pins  36  which pass through the flange  35   b  and may be engaged in selected ones of a series of holes  37  drilled through the flanges  35   a  and  35   b  at regular spacing (suitably 250 mm). Similar holes are drilled in the rail  22  at 500 mm intervals. In this way the fore and aft position of the arch can be adjusted in regular increments (in this case 250 mm). A locking arrangement (not shown) is provided for the pins. In the course of adjusting the position of the arch, it will be prevented from toppling by the engagement of the wheels  33  with the flanges of the rail  22 .  
         [0023]    A further feature of the mounting arrangement shown in FIGS. 6 and 7 allows for selective tilting of the arch. This is achieved by supporting the feet of the arch on the runners  32  by means of pins  38 , which are selectively engaged with upper and lower locking holes  39  and  40  in the regions of the fore and aft edges of the arch. It will be appreciated that if both the fore and aft pins  38  are located in the lower holes  40 , the arch will be helical. If the aft pin  38  is located in the upper hole  39  and the forward tilted forward. preferably by pin  38  in the lower hole  40 , the arch will be approximately 10 degrees. Reversing the positions of the pins  38  will of course tilt the mast to the stern. Complete removal of the fore or aft pins  38  will allow the arch to be lowered to the aft or foredecks respectively.  
         [0024]    In normal sailing conditions the sail is controlled by means of a control line  31  which extends from the rear of the bottom spar to the cockpit. By moving the carrier on its track around the arch, the sail can be pivoted through as much as plus or minus up to 90 degrees, and indeed can be placed horizontally when the vessel is at anchor.  
         [0025]    As an alternative to the normal practice of reefing, in the present system, the sail can be leant into the wind by adjusting the carrier  17  to windward and the bottom line  19  to leeward under strong wind conditions. The sail is leant into the wind. This reduces the effective area of the sail, and also tends to lift the leeward hull, counteracting the tendency for the leeward hull to be driven deeper, a disadvantage of a Bermudan rig. As a consequence, the vessel can be sailed faster in heavy wind conditions. In even heavier winds, slackening the tension in the bottom line  19  will allow the sail to increase its curvature with the effect of reducing its power.