Abstract:
A lifting-sail rig and method comprising airfoils, or efficient aerodynamically shaped leading edge soft sails, supported by an improved non-interfering fixed mast rig positioned away from the lifting-sail for increased aerodynamic efficiency and ease of sail or airfoil control. Stable sailboat performance is achieved at a higher speed for multihulls and widened beam monohulls for supporting the lifting-sail rig. The improved lifting-sail rig balances the large wind driven forces that have resulted in the capsizing of conventional monohull sailboats, and the pitch poling of multihulls.

Description:
CROSS REFERENCE PRIORITY DATA 
     Provisional Patent Application No. 60/302,326 filed on Jun. 29, 2001. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to sailboats and particularly to an improved lifting-sail rig and method for multihulls and wide beam monohulls with a simple, effective, seaworthy apparatus for the control of heeling with the capability for completely canceling the overturning moment. 
     2. Description of the Prior Art 
     The conventional stayed, fixed mast rig used with a weighted keel, monohull sailboat has proven successful in providing the most stable mode of sailing in heavy winds and seas, with shortened sail or reefing to avoid capsizing. The weighted ballast on a keel has proven successful in providing operating stability, but the added weight, keel surface area, and the heeled hull shape increases water drag. Smaller conventionally rigged, centerboard sailboats utilize crew weight to windward with sail easing and sail reefing, to balance the overturning moment created by high wind forces. Control of all conventional sailboats is limited by the need for ultimately “luffing”, easing the sail outboard, or reefing for reducing the effective sail area to maintain stability against capsizing. Heeling results in loss of efficiency as a result of the added downward sail force or “weight”, which greatly increases hydrodynamic drag, and a large loss in forward aerodynamic driving force. At small angles of heel a multihull having a wide beam and narrow hulls with reduced inertial drag, has proven more stable than a wide beam monohull. However, like any non-ballasted, lightweight sailboat, a multihull tends to capsize when it reaches negative stability in a heavy wind, usually at heel angles greater than about 50 degrees. The maximum design value of the its achieved righting moment limits a sailboat&#39;s “power to carry sail”, whereas increased speed is directly related to the ability to carry a larger sail area where conventional sail rigs are deficient. 
     The relatively small “windsurfer” is the only commercially successful seaworthy lifting-sail craft that completely balances the overturning moment with crew weight. The windsurfer is a one person, aerodynamically efficient, simple, high-speed sailboard. U.S. Pat. No. 3,487,800 to Schweitzer and Drake discloses this lightweight windsurfer with a simple, base pivoting carbon fiber mast, integral with an aerodynamically shaped leading sail edge. The windsurfer sail is manually controlled by the operator, who maneuvers the sailboard by tilting the sail with an attached wishbone boom, fore and aft for steering, and outboard to windward for lifting and balance. The windsurfer operator can skillfully exercise control without capsizing in strong winds and turbulent seas. The planing windsurfer is the only production sailboat that has achieved a world speed record of 45 knots, even though in a 50 knot wind. Depending on the strength of the wind, by tilting the sail rig to windward, the operator can obtain near “lift-off” conditions where hydrodynamic drag approaches zero. A skilled operator can actually lift the sailboard out of the water briefly and return safely to the water surface. However, the upside growth of windsurfing has been limited by the fact that relatively strong wind conditions are required to optimize windsurfer sailing speed. For high speed in light to moderate winds, a large sail area is required in excess of about 10 square meters. But, only those strong sailors over 6 feet tall can generally realize the strength with enough moment arm to handle these larger sail areas with ease and effectiveness in a strong wind. Limited by the height and strength of the average human operator, the most utilized sail area is actually reduced to about 5 or 6 square meters. Consequently, the windsurfer with its operator supported tilting mast and lifting-sail has a ratio of maximum sail area to total weight ratio much lower than can be achieved with conventional monohulls and multihulls having conventional mounted fixed stayed, or carbon fiber masts. 
     One of the most rapidly growing high performance sailboat categories is multihulls. Catamarans or trimarans can carry a large sail area, but are more difficult to control than the simpler windsurfer. Multihulls have a tendency in a strong wind to heel to an angle of negative stability, pitch pole, or capsize. However, stayed fixed mast sailboats have proven to have a suitable platform for practical innovations that enhance performance and stability. Conventional vertical sailing rigs may have simple fore and aft stays and side stays or shrouds that substantially support the fixed mast in pitch, roll, and yaw. Alternating pitching forces with the high stress concentrations do not cause premature failure of conventional rigging, and is adequately strong and seaworthy to withstanding the high cyclical stresses from the sail pitching moment in rough seas. 
     An experimental sailboat named Yellow Pages Endeavor, with an efficient 300 square foot airfoil supported by three stays attached to three short planing hulls asymmetrically arranged, attained the worlds speed record in October 1993 of over 46.5 knots or 53.6 mph in only an 18 knot breeze in relatively smooth water. Furthermore, the iceboat with a stayed mast-sail rig is a good example of the highest speed potential of over 80 knots with extremely low drag on ice. 
     Prior art lifting-sail arrangements including those that physically mount and rotate the sail about a fixed mast, have proven to be overly complex and difficult to operate. Furthermore, they are difficult to tack or change direction, and they do not have the capability to fully counteract heeling for a complete righting moment. A swing sail rig disclosed in U.S. Pat. No. 4,799,443 to Vogel, comprises a sail luff boom mounted on a single multi-hinge fitting at a pivot point above the sail center of effort with the upper region of the luff boom attached to the top of a short fixed mast. The single multi-hinge fitting connects the luff boom to the mast for both supporting and articulating the swing sail rig. The small multi-hinge mast fitting attached at the mast head allows the sail to rotate vertically around the mast, while rotating about the axis of the luff boom for altering the angle of attack of the sail to the relative wind direction. At the same time the sail can swing or tilt outboard to some extent under the driving force of the wind. Difficulty in maneuvering the luff boom, fixed only to the single mast support fitting results in mechanical interference with the mast. Also, the fixed mast placed in front of the luff boom in close proximity to the swing sail, results in aerodynamic sail interference with increased drag. When sailing to windward, the most critical and difficult point of sailing, the single multi-hinge fitting would tend to have difficulty enduring the very large torsional stresses from the sail forward driving force, and the large pitching moment between the sail center of effort and the multi-hinge fitting, particularly as the sail tends to twist or pitch aft. The strength may be improved as disclosed in U.S. Pat. No. 6,189,472 to Duncan by providing support of the swing sail with an additional swing boom to the boat deck. However, the short swing boom length required to adequately strengthen the rig, limits the outboard swing and the subsequent achievable righting moment. An early U.S. Pat. No. 1,670,936 to McIntyre discloses an early lifting-sail and mast apparatus allowing the sail center of effort to swing outboard to the lee side of the mast, and to pass thru the keel center of lateral resistance for realizing a complete righting moment for all points of sailing. The lee outboard support for the complex rotating lifting-sail apparatus includes a sprit-boom mechanism coupled to the fixed mast, but not substantially supported against pitch, roll, and yaw. 
     Consequently, improved simpler, more substantial and reliable fixed mast lifting-sail rig and method is needed for controlling heeling with the capability for a complete righting moment under high wind operating conditions. The simple lifting-sail rig apparatus and method of the present invention, with effective operator control, is more aerodynamically efficient, being positioned forward of a conventional fixed mast rigging with a mast-sprit. A preferred embodiment utilizes a low drag carbon fiber, simplified mast rig with the improved high aspect ratio lifting-airfoil or lifting-sail, that operates automatically with rapid response in the same simple, natural way of a conventional sail. To achieve the foregoing and other objects in accordance with the purpose of the present invention, according to one aspect of these novel improvements, various related versions of the preferred lifting-sail rig and method are disclosed. 
     SUMMARY OF THE INVENTION 
     The improved airfoil or lifting-sail rig for driving or propelling a sailboat, may comprise preferably, a simple carbon fiber aft positioned mast with a lower vertical portion and a short, horizontal mast-sprit upper portion projecting forward from the top of the vertical mast portion for supporting the lifting-sail or lifting-airfoil. An aerodynamic shaped luff-spar is attached to the leading edge of the sail or integral with the airfoil leading edge design. A universal head coupling connects the head end of the luff-spar to the middle region of the mast-sprit portion for unrestricted upward tilting or lifting of the sail or airfoil at the mast-sprit to produce a complete righting moment. Support of the luff-spar against fore and aft pitching is controlled, particularly when sailing to windward by a substantial guy wire that may be a rigid rod or fore-spar. The guy wire is connected between a luff-spar coupling that may be located in the mid region of the luff-spar and a coupling at the forward end of the mast-sprit. This simple method of tilting the airfoil or sail to adjust the heel control is about the axis defined by the mast sprit. The angle of attack of the lifting-sail is altered by rotating the luff-spar about an axis defined by a line between the universal head coupling and the luff-spar coupling. 
     An alternative lifting-sail rig embodiment may comprise a stayed mast with spreaders that prevent buckling of the mast and distortion of the rig during the pitching, (torsional) yawing, and rolling motion of the sailboat. Again a short, horizontal mast-sprit portion projects forward from the top region of the aft mast for supporting an efficient lifting-sail. 
     The efficient lifting-sail apparatus is easily controlled by the operator with the aid of the wind naturally forcing the sail into the desired attitude of lift angle and angle of attack in the same manner as a conventional sail. The sail or airfoil may be operated by two sheets, one to control horizontal (outward lifting) tilt preferably at the tack, and the other to control the upper edge of the sail or airfoil may include a top boom with a main sheet leading from the top region of the mast for controlling the angle of attack by the operator. Alternatively, a main sheet leading from the clew may be used to control rotation of the sail angle of attack to the relative wind direction. The balancing lifting force of the sail may un-weight the sailboat and reduce the hydrodynamic drag to a near zero “lift-off” state, or a complete righting moment may be achieved by the unrestricted upward tilting of the sail or airfoil as desired by the operator. 
     The objective is to increase the improved lifting-sail rig apparatus high wind speed potential beyond conventional sailboats, with ease of handling, safety, durability, and control in heavy winds and seas. An improved aerodynamically efficient and reliable sailboat, can achieve higher speeds with stability and control over capsizing on all points sailing., 
     OBJECTS AND ADVANTAGES 
     A primary objective of this present invention is to provide an improved lifting-sail rig high speed sailboat, that achieves stability and control over capsizing on all points sailing, with ease of handling in heavy winds and seas. 
     Another objective is to provide a simple, efficient lifting-sail rig capable of easily and naturally inclining upward to a high lift position, for optimum control of the heeling force with the capability for complete balance of the overturning moment. 
     Another objective is to provide a simple, efficient lifting-sail rig capable of an unrestricted upward lifting-sail orientation for the maximum lift position of the sail rig in very strong winds, with the lifting resultant passing directly through the keel center of lateral resistance for complete balance of the overturning moment. 
     Another objective is to achieve a low aerodynamic drag lifting-sail stayed mast and rigging with good sea keeping ability and superior structural strength. 
     Another objective is to achieve a low aerodynamic drag lifting-sail simple carbon fiber mast and rigging with good sea keeping ability and superior structural strength. 
     Another objective is to achieve a low aerodynamic drag lifting-sail stayed mast and rigging with good sea keeping ability and superior structural strength. 
     Another objective of this present invention is to control the lifting-sail rig with the wind naturally forcing the sail into the desired attitude of lift angle and angle of attack. 
     Still another objective of this invention is to achieve a larger sail coefficient of lift, higher aspect ratio, more efficient sails or airfoils to achieve a higher overall driving force. 
     Another objective is to utilize the improved stability of the lifting-sail result afforded by the “windsurfer” with the attendant, un-weighted, minimum area hull planing capability with reduced hull drag. 
     Another objective is to achieve an apparatus with maximum spacing between the sail center of effort and the keel center of lateral resistance to permit the angle of the lifting-sail to be as near vertical as feasible with the overturning moment completely balanced. 
     Another objective is to provide a method for complete balance of the overturning moment of a lifting-sail rig multihull with only one hull in the water for reduced drag, by causing the lifting-sail to heel the catamaran to windward, thereby moving the center of lateral resistance to the keel of the windward hull. 
     Another objective is to provide complete balance of the overturning moment of a lifting-sail rig trimaran, moving the center of lateral resistance to the fin of the windward ama, or outrigger of the trimaran, furthest to windward from the lifting rig center of effort. 
     Another objective is to provide a low profile drag airfoil or sail rig for a safe “hove to”, or non driving condition, whereby the sail rig may be orientated by the wind force into near horizontal, or vertical “luffing” position facing into the wind. 
     Another objective is to provide a safe “hove to”, or non-driving condition, whereby a lifting sail or rigid airfoil may be lowered into a rest or nesting position on the deck for mooring or docking the sailboat. 
     Another objective of this invention is to permit the use of a delta shaped sail or airfoil with an efficient tapered, aerodynamic shape to provide a higher coefficient of lift, lower center of effort, lifting-sail rig with ease of handling and good sea keeping ability, which may be light weight and inflatable similar to conventional delta shaped hang-gliders and kites. 
     Another objective is to provide dual airfoils, as a fixed bi-plane, or in tandem that may be rotated into the advantageous, efficient “safe leeward position” configuration, to lower the center of effort and increase the righting moment with minimum aerodynamic drag. 
     Another objective is to maximize the hull speed in relatively calm seas, with a plurality of small surface area, short planing pods having reduced hydrodynamic drag. 
     Another objective is a craft comprising a least three, but preferably four widely spaced of short planing pods that may be interconnected in a symmetrical array, with small hydrofoils for control and lift. 
     Another objective is to provide an adequate space between short planing hulls for a crew cockpit, cabin or living quarters without interference from the lifting-sail rig. 
     Another objective is to maximize the hull speed in ocean going windward performance, with small surface area, very long narrow semi-circular hulls having low wave drag and low inertial drag. 
     Another objective is to achieve ultimate safety and heavy weather multihull operation, sea-keeping ability, and a built in life saving provision, particularly for trimarans, catamarans, or similar multihull craft adapted with at least one self righting, detachable “life support” elevated capsule or large crew pod with a self-sufficient spaceship-like quality. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention. 
     FIG. 1 is an explanatory diagram of first preferred embodiment showing an optimum positioning method of windward tilting the lifting-sail rig to cancel the overturning moment, the rig comprising a vertical mast and an attached horizontal mast-sprit, with a low aerodynamic drag sail hinged from the mast sprit, inward canted hydrofoils, and four simple supporting stays suitable for a wide beam monohull or a multihull. The unique mast-sprit rig with minimum spars and stays of low drag is positioned aft of the lifting-sail to result in no aerodynamic sail interference. 
     (FIG. 1 a  shows photographs of this simple operating lifting-sail rig apparatus reduced to practice according to the present invention.) 
     FIGS. 2 and 3 are the explanatory diagrams of a first preferred embodiment of the lifting-sail rig apparatus, comprising a low aerodynamic drag sail, a carbon fiber vertical mast and horizontal mast-sprit, inward canted keels or hydrofoils, and four simple supporting stays mounted on a multihull such as a catamaran. The minimum mast structure is positioned aft of the lifting-sail to prevent aerodynamic interference. 
     FIG. 4 is an explanatory diagrams of the first preferred embodiment of the lifting-sail rig, comprising a low aerodynamic drag symmetrical wing with a rear flap, a carbon fiber vertical mast with a horizontal mast-sprit, inward canted hydrofoils, and four simple supporting stays. The minimum mast structure is positioned aft of the lifting-sail to prevent aerodynamic interference. 
     FIG. 5 is an explanatory diagram of the first preferred embodiment of the lifting-sail rig apparatus, comprising a low aerodynamic drag, high coefficient of lift, symmetrical slotted airfoil with camber reversing, a formed or carbon fiber vertical mast with a horizontal mast-sprit, canted hydrofoils, and four simple supporting stays. The minimum mast structure is positioned aft of the lifting-sail to prevent aerodynamic interference. 
     FIG. 6 is an explanatory diagrams of a preferred embodiment of the lifting-sail rig apparatus, comprising a low aerodynamic drag sail, a carbon fiber, vertical mast including a flexible bent mast-sprit, inward canted hydrofoils, and four simple supporting stays. The minimum mast structure is positioned aft of the lifting-sail to prevent aerodynamic interference. 
     FIGS. 7 and 8 are the explanatory diagrams of a first preferred embodiment of the lifting-sail rig, comprising a low aerodynamic drag sail, an “A” Frame mast with a horizontal mast-sprit, inward canted hydrofoils, and dual supporting forestays mounted on a sailboat such as a catamaran. The low aerodynamic drag lifting-sail or lifting-airfoil may be lowered between the “A” frame to a “docking” position on the deck of the wide beam sailboat or multihull. The minimum “A” Frame mast structure is positioned aft of the lifting-sail to prevent aerodynamic interference. 
     FIGS. 9 and 10 are the explanatory diagrams of a first preferred embodiment of the lifting-sail rig, comprising dual low aerodynamic drag sails with two adjacent lifting-sails that take advantage of the “slot effect” derived by the combined conventional jib and mainsail interaction, a vertical mast with a mast-sprit, canted hydrofoils, spreaders at the mast maximum buckling stress point, and four simple supporting stays. The minimum mast structure is positioned aft of the lifting-sail to prevent aerodynamic interference. 
     FIG. 11 is an explanatory diagram of a preferred embodiment employing the “biplane” effect with two widely spaced lifting sails or lifting airfoils resulting in a lowered center of effort lifting-sail rig apparatus and method. The biplane mounted on a fixed mast with a horizontal yardarm may be rotated to the more effective “safe leeward position” configuration. The lowered center of effort, provides a more effective righting moment. Also, with a large free area on the main hull self righting, detachable “life support” elevated capsule or large crew pod with a spaceship-like quality may be utilized as a crew cockpit, cabin or living quarters without interference from the rotating lifting-sail rig. 
     FIGS. 12 and 13 are the explanatory diagrams of a first preferred embodiment of the lifting-sail rig apparatus to maximize the hull speed in relatively calm seas, with small surface area, short planing hulls or pods. Having reduced hydrodynamic drag, particularly as a catamaran, trimaran, or other unique craft with a plurality, of three, preferably four widely spaced, short planing pods for maximum stability, are interconnected in a symmetrical array, with hydrofoils for lift and steering control. A unique joined tandem lifting-airfoil is mounted on a horizontal yardarm for upward tilting. The horizontal yardarm is mounted on a fixed mast for vertical rotation of the lifting-airfoil, to vary the angle of attack and the camber with rear flaps. The low inertia, simple joined tandem lifting-airfoil mounted on the rotating yardarm results in a lowered center of effort. 
     FIG. 14 is an explanatory diagram of a preferred embodiment employing an efficient delta shaped sail or wing with the lifting-sail rig apparatus and method. With a lower center of effort, the delta lifting-sail rig is preferably light in weight and inflatable similar to conventional delta shaped hang-gliders and kites. 
     FIGS. 15 and 16 are the explanatory diagrams of a preferred embodiment of the lifting-sail rig, for offshore cruising with a heavy duty mast and mast-sprit reinforced with additional, heavy duty spreaders and stays. 
     FIG. 17 is an explanatory diagram of an alternative embodiment comprising a lifting-rotor used in place of a lifting-sail. The lifting-rotor rig generates aerodynamic driving force only when the airfoil cylinder is rotated, or driven about its central axis. Therefore, the driving force is safely controlled by the speed of rotation even in strong winds. 
     FIG. 18 is an explanatory diagrams of an alternative embodiment of the lifting-sail rig, comprising a low aerodynamic drag sail, a vertical mast with a mast-sprit, inward canted hydrofoils, and four simple supporting stays. The aerodynamic mast and rig with minimum spars and stays of low drag is positioned forward and away from the lifting-sail with the mast-sprit extending aft. 
    
    
     REFERENCE NUMERALS 
     Lifting-Sail Method and Apparatus  2   
     Aft Mast Lifting-Sail Rig Apparatus  3   
     Bent Flexible Aft Mast Lifting-Sail Rig Apparatus  4   
     “A” Frame Aft Mast Lifting-Sail Rig Apparatus  5   
     Jib/Mainsail Aft Mast Lifting-Sail Rig Apparatus  6   
     Rotating Bi-Plane Lifting-Sail Rig Apparatus  7   
     Joined Dual Tandem Airfoil Lifting-Sail Rig Apparatus  8   
     Delta Airfoil Aft Mast Lifting-Sail Rig Apparatus  9   
     Reinforced Aft Mast Midpoint Spreader Lifting-Sail Rig Apparatus  10   
     Forward Mast Lifting-Sail Rig Apparatus  11   
     Lifting-Sail Docking Apparatus  12   
     Bent Flexible Aft Mast Lifting-Rotor Rig Apparatus  13   
     Extended Beam Planing Hull  14   
     Main Deck  14   d    
     Trimaran Main Hull  14   t    
     Starboard Hull  14   s    
     Port Hull  14   p    
     Rudder  16   
     Starboard Rudder  16   s    
     Port Rudder  16   p    
     Keel or Hydrofoil  18   
     Keel or Hydrofoil Center of Lateral Resistance  18   clr    
     Starboard Keel or Hydrofoil  18   s    
     Port Keel or Hydrofoil.  18   p    
     Lifting-Sail  20   
     Lifting-Jib  20   j,  Lifting-Mainsail  20   m    
     Sail Center of Effort  20   ce    
     Jib Sheet  21   j,  Main Sheet  21   m    
     Symmetrical Lifting-Airfoil  22   
     Symmetrical Lifting-Airfoil Rear Flap  22   r    
     Symmetrical Lifting-Airfoil Forward Wing  22   f    
     Symmetrical Lifting-Airfoil Middle Wing  22   m    
     Lifting-Airfoil Center of Effort  22   ce    
     Symmetrical Delta-Shaped Lifting-Airfoil  23   
     Symmetrical Joined Tandem Lifting-Airfoil  24   
     Symmetrical Lifting-Airfoil Articulating Linkage  26   
     Lifting-Sail Symmetrical Airfoil Luff-Spar  28   
     Lower Sail Boom  30   
     Lower Wishbone Sail Boom  30   w    
     Sail Batten  31   
     Upper Sail Boom  32   
     Upper Wishbone Sail Boom  32   w    
     Mast-Sprit/Luff-Spar Head Universal Coupling  34   
     Mast-Sprit/Luff-Spar Head Universal Halyard  34   h    
     Symmetrical Airfoil Fore-Spar  36   
     Guy wire  36   g    
     Mast-Sprit/Luff-Spar Halyard  36   h    
     Upper Sail/Airfoil Angle of Attack Control Sheet  38   
     Fore-Spar/Luff-Spar Coupling  40   
     Mast-Sprit Coupling  42   
     Mast-Sprit  44   
     Flexible Bent Mast-Sprit  46   
     “A” Frame Mast  48   
     “A” Frame Starboard Leg  48   s    
     “A” Frame Port Leg  48   p    
     Symmetrical Airfoil Vertical Mast  50   
     Mast-Sprit Stay  52   
     Luff-Spar Head  54   
     Luff-Spar Tack  56   
     Lower Boom/Sail or Airfoil Angle of Attack Control Sheet  58   
     Luff-Spar/Sail or Airfoil Tilt Sheet  60   
     Starboard Forestay  62   s    
     Port Forestay  62   p    
     Starboard Backstay  64   s    
     Port Backstay  64   p    
     Vertical Mast Maximum Buckling Stress Point  66   
     Starboard Mast Spreader  66   s    
     Port Mast Spreader  66   p    
     Bi-Plane Rotary Yardarm  68   
     Bi-Plane Rotary Yardarm Bearing  69   
     Planing Multihull  70   
     Elevated Crew Capsule  71   
     Planing Pods  72   
     Starboard mast-sprit spreader  74   s    
     Port mast-sprit spreader  74   p    
     Starboard mast-sprit stay  75   s    
     Port mast-sprit stay  75   p    
     Starboard mast-sprit jumper stay  76   s    
     Port mast-sprit jumper stay  76   p    
     Starboard mast jumper stay  78   s    
     Port mast jumper stay  78   p    
     Lifting-Rotor Center Bearing  79   
     Lifting-Rotor  80   
     Lifting-Rotor End Plates  81   
     Lifting-Rotor Lower Bearing  82   
     Lifting-Rotor Drive Motor  83   
     Lifting-Rotor Axis of Rotation  84   
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1 is an explanatory diagram showing the lifting-sail principle of the first preferred lifting-sail rig embodiment. As shown with this lifting-sail principle, the optimum heeling position with minimum drag is too windward with the lee hull  14   s  out of the water. The leeward tilt angle of the lifting-sail  20  cancels the overturning moment with the side force Fs at the lifting-sail  20  center of effort  20   ce  passing through the keel or centerboard  18   p  center of lateral resistance  18   cr  with force Fr equal to lifting-sail  20  side force Fs. The lifting-sail rig method and apparatus  2  comprises a vertical mast  50  with a horizontal mast-sprit  44 , supporting a low aerodynamic drag lifting-sail  20  hinged from the mast sprit  44  with a universal coupling  34 . The vertical mast  50  with a mast-sprit  44  is positioned aft of the lifting-sail  20  without aerodynamic interference. Inward canted hydrofoil  18   s  on starboard hull  14   s,  and inward canted hydrofoil  18   p  on port hull  14   p  provides the counteracting Force Fr of lateral resistance. With the overturning moment completely balanced by the lifting-sail rig method and apparatus  2 , the angle of the lifting-sail  20  should be as near vertical as possible to maintain the highest forward driving force. This is accomplished with the beam distance maximized between the lifting-sail  20  center of effort  20   ce  and the keel or centerboard  18   p  center of lateral resistance  18   cr.  The preferred method is to heel the catamaran to windward with the lifting-sail  20 , thereby lifting the lee hull  14   s  out of the water, and moving the center of lateral resistance  18   cr  to the keel  18   p  of the windward hull  14   p.  Starboard  16   s  and port  16   p  rudders provide directional control. With a trimaran, as shown in FIG. 11, the center of lateral resistance  18   r  is on the inward canted fin  18   p  of the windward ama, or outrigger  15   p  of the trimaran, which is furthest to windward from the lifting-sail  20  center of effort  20   ce.    
     The vertical component of the driving force Fs of lifting-sail  20 , un-weights the starboard hull  14   s , reducing the hydrodynamic drag to zero in the “lift-off” state. The simple, efficient lifting-sail  20  is capable of easily and naturally inclining upward to a high lift position, with safety, stability, and optimum control of the lifting force Fs for complete balance of the overturning moment. The lifting-sail  20  has the stability of the “windsurfer” method along with the attendant, un-weighted, minimum area hull planing capability, ease in rapid tacking, and reduced hull drag as a result of the upward aerodynamic force. 
     FIGS. 2 and 3 are the explanatory diagrams of a first preferred embodiment of a simple, carbon fiber or formed aft mast lifting-sail rig apparatus  3 . The improved lifting-sail  20  comprises a fixed vertical mast  50  with a short mast-sprit  44  projecting forward at the top of the vertical mast  50  for supporting the lifting-sail  20 . The vertical mast  50  is positioned aft of the lifting-sail  20  without aerodynamic interference. The mast sprit  44  is laterally supported by two widely spaced forestays, starboard  62   s  and port  62   p.  The vertical mast  50  is supported by two widely spaced backstays, starboard  64   s  and port  63   p.  Inward canted hydrofoil  18   s  on starboard hull  14   s , and inward canted hydrofoil  18   p  on port hull  14   p  provide the lateral resistance. Starboard  16   s  and port  16   p  rudders provide directional control. An aerodynamically shaped, symmetrical airfoil luff-spar  28  is attached to or integral with the leading edge of the lifting-sail  20  extending from the luff spar tack  56  to the luff spar head  54  of the lifting-sail  20 . The mast-sprit  44  luff-spar  28  universal coupling  34  connects the head end  54  of the luff-spar  28  to the middle region of the mast-sprit  44  thereby hinging the lifting-sail  20  for unrestricted upward tilting to produce a complete righting moment. Support of the luff-spar  28  against aft pitching of the lifting-sail  20  is controlled, particularly when sailing to windward by a guy wire  36   g , or alternatively, a symmetrical airfoil fore-spar  36 , particularly for fore pitching of the lifting-sail  20  when sailing downwind. 
     The fore-spar  36 , or alternatively guy wire  36   g , is connected between a luff-spar coupling  40  located in the mid region of the luff-spar  28  and a coupling  42  at the forward end of the mast-sprit  44 . Simple rotation of the lifting-sail  20  for adjusting its angle of attack to the relative wind is about an axis along the luff-spar  28  defined by a line between the luff-spar coupling  40  attached on the leading edge of the luff-spar  28  and the mast-sprit-spar universal coupling  34  located at the mid-region of the mast-sprit  44 . Upper wishbone booms  32   w  and lower wishbone booms  30   w  are attached to the luff-spar  28  for rotating the lifting-sail  20  to reverse and vary the camber of the lifting-sail  20 . A lower angle of attack control sheet  58  may be attached to the lower boom  30   w  and lead to the deck  14   d  for additional control. Tilt sheet  60  for lifting-sail  20  is also attached to the lower boom  30   w  and leads aft to the deck  14   d  for ease of lifting-sail  20  tilt adjustment, while tensioning the guy wire  36   g , particularly for sailing down wind. 
     FIG. 4 is an explanatory diagram of the first preferred embodiment of the aft mast lifting-sail rig apparatus  3  shown in FIGS. 2 and 3, but with a higher coefficient of lift, lower aerodynamic drag, symmetrical lifting-airfoil  22  comprising a symmetrical forward wing  22   f  with a rear flap  22   r.  Symmetrical lifting-airfoil articulating linkages  26  are attached to the symmetrical forward wing  22   f,  and the rear flap  22   r  to reverse and vary the camber of symmetrical lifting-airfoil  22 . The angle of attack of the lifting-symmetrical airfoil  22 , is controlled primarily by an upper control sheet  38  leading from the trailing end of the top symmetrical airfoil articulating linkage  26  to the mast-sprit  44  and leading down to the deck  14   d  for rotating the symmetrical lifting-airfoil  22  with ease of adjustment. 
     Inward canted hydrofoil  18   s  on starboard hull  14   s , and inward canted hydrofoil  18   p  on port hull  14   p  provide the lateral resistance. Starboard  16   s  and port  16   p  rudders provide directional control. A lower angle of attack control sheet  58  may be attached to the lower boom  30   w  or and leads to the deck  14   d  for additional control. Tilt sheet  60  for lifting-sail  20  is also attached to the lower boom  30   w  and leads aft to the deck  14   d  for lifting-sail  20  tilt adjustment, while tensioning the guy wire  36   g , particularly for sailing down wind. Support of the luff-spar  28  against aft pitching of the lifting-sail  20  may be controlled by a symmetrical airfoil fore-spar  36 , particularly for fore aft pitching of the lifting-sail  20 . 
     FIG. 5 is an explanatory diagram of the first preferred embodiment of the aft mast lifting-sail rig apparatus  3  shown in FIGS. 2 and 3, and FIG. 4, but with a slotted high coefficient of lift, symmetrical lifting-airfoil  22  with a low aerodynamic drag, symmetrical forward wing  22   f,  a middle wing  22   m,  and a rear flap  22   r.  Symmetrical lifting-airfoil articulating linkages  26  are attached to the symmetrical forward wing  22   f,  the middle wing  22   m,  and the rear flap  22   r  to reverse and vary the camber of symmetrical lifting-airfoil  22 . The angle of attack of the lifting-symmetrical airfoil  22 , is controlled primarily by an upper control sheet  38  leading from the trailing end of the top symmetrical airfoil articulating linkage  26  to the mast-sprit  44  and leading down to the deck  14   d  for rotating the symmetrical lifting-airfoil  22  with ease of adjustment. Inward canted hydrofoil  18   s  on starboard hull  14   s , and inward canted hydrofoil  18   p  on port hull  14   p  provide the lateral resistance. Directional control is provided by starboard  16   s  and port  16   p  rudders. A lower angle of attack control sheet  58  may be attached to the lower boom  30   w  and lead to the deck  14   d  for additional control. Tilt sheet  60  for lifting-sail  20  is also attached to the lower boom  30   w  and leads aft to the deck  14   d  for ease of slotted airfoil  22  tilt adjustment, while tensioning the guy wire  36   g , particularly for sailing down wind. Support of the luff-spar  28  against aft pitching of the lifting-sail  20  is controlled, particularly when sailing to windward by the guy wire  36   g , or alternatively, a symmetrical airfoil fore-spar  36  may be used, particularly for fore pitching of the lifting-sail  20  when sailing downwind. 
     FIG. 6 is an explanatory diagrams of a first preferred embodiment of a bent flexible mast lifting-sail rig apparatus  4 , comprising a fixed carbon fiber vertical mast  50  with a short bent flexible mast-sprit  46  projecting forward at the top of the vertical mast  50  for supporting the lifting-sail  20 . The vertical mast  50  is positioned aft of the lifting-sail  20  without aerodynamic interference. The mast sprit  46  is laterally supported by two widely spaced starboard  62   s  and port  62   p  forestays. The vertical mast  50  may be supported by two widely spaced starboard  64   s  and port  63   p  backstays. An aerodynamically shaped, symmetrical airfoil luff-spar  28  is attached to or integral with the leading edge of the lifting-sail  20  extending from the luff spar tack  56  to the luff spar head  54  with battens  31  spaced vertically to maintain the shape of the lifting-sail  20  The bent mast-sprit  46  to luff-spar  28  universal coupling  34  connects the luff spar head  54  of the luff-spar  28  to the middle region of the bent mast-sprit  46  for hinging the lifting-sail  20  with the universal coupling  34  for unrestricted outward tilting of the lifting-sail  20  to produce a complete righting moment. Support of the luff-spar  28  against fore and aft pitching of the lifting-sail  20  is preferably controlled by a symmetrical airfoil fore-spar  36 . Alternatively a guy wire  36   g  may be utilized under tension when sailing downwind. The symmetrical airfoil fore-spar  36  is connected between a luff-spar coupling  40  located in the mid region of the luff-spar  28  and a coupling  42  at the forward end of the bent mast-sprit  46 . Inward canted hydrofoil  18   s  on starboard hull  14   s , and inward canted hydrofoil  18   p  on port hull  14   p  provide the lateral resistance. Directional control is provided by starboard  16   s  and port  16   p  rudders. Simple rotation of the lifting-sail  20  for adjusting its angle of attack to the relative wind is about an axis defined by a line between the luff-spar coupling  40  attached on the leading edge of the luff-spar  28  and the mast-sprit-spar universal coupling  34  located at the mid-region of the mast-sprit  46 . Upper wishbone boom  32   w  is attached to the luff-spar  28  to reverse and vary the camber of the lifting-sail  20 . The angle of attack of the symmetrical lifting-airfoil  22 , is controlled primarily by an upper control sheet  38  leading from the trailing end of the upper wishbone boom  32   w  to the bent mast-sprit  46  and leading down to the deck  14   d  for rotating the symmetrical lifting-airfoil  22  with ease of adjustment. Lower wishbone boom  30   w  is attached to the luff-spar  28  to reverse and vary the camber in the lower region of the lifting-sail  20 . The angle of attack of the symmetrical lifting-airfoil  22 , is controlled primarily by an lower control sheet  58  leading from the trailing end of the upper wishbone boom  32   w  to the bent mast-sprit  46  and leading down to the deck  14   d  for rotating the lower region of the symmetrical lifting-airfoil  22 . Lifting-sail  20  tilt sheet  60  is also attached to the lower short sail boom  30  and leads aft to the deck  14   d  for ease of tilt adjustment. 
     FIGS. 7 and 8 are the explanatory diagrams of a first preferred embodiment of an “A” Frame aft mast lifting-sail rig apparatus  6 , comprising an “A” Frame mast  48  with a short mast-sprit  44  projecting forward supported by mast-sprit stay  52  at the top of the “A” Frame mast  48  for supporting the lifting-sail  20 . The “A” Frame mast  48  is positioned aft of the lifting-sail  20  without aerodynamic interference. The mast sprit  44  is laterally supported by two widely spaced starboard  62   s  and port  62   p  forestays. Inward canted hydrofoil  18   s  on starboard hull  14   s , and inward canted hydrofoil  18   p  on port hull  14   p  provide the lateral resistance: Directional control is provided by starboard  16   s  and port  16   p  rudders. 
     The “A” Frame mast  48  comprises two widely spaced “A” Frame legs, starboard  48   s  and port  48   p  supported at the maximum buckling stress point  66  by mast spreaders, starboard  66   s  and port  66   p  with starboard  64   s  and port  64   p  backstays. An aerodynamically shaped, symmetrical airfoil luff-spar  28  is attached to or integral with the leading edge of the lifting-sail  20  extending from the luff spar tack  56  to the luff spar head  54 . The mast-sprit  44  to luff-spar  28  universal coupling  34  connects the luff-spar head  54  to the middle region of the mast-sprit  44  for hinging the lifting-sail  20  for unrestricted upward tilting to produce a complete righting moment. Support of the luff-spar  28  against fore and aft pitching of the lifting-sail  20  is preferably controlled by a symmetrical airfoil fore-spar  36 . Alternatively a guy wire  36   g  may be utilized under tension when sailing downwind. 
     The symmetrical airfoil fore-spar  36  is connected between a luff-spar coupling  40  located in the mid region of the luff-spar  28  and a coupling  42  at the forward end of the mast-sprit  44 . Simple rotation of the luff-spar  28  for adjusting the lifting-sail  20  angle of attack to the relative wind is about an axis defined by a line between the luff-spar coupling  40  attached on the leading edge of the luff-spar  28  and the mast-sprit-spar universal coupling  34  located at the mid-region of the mast-sprit  44 . Upper boom  32  is attached to the luff-spar head  54  to reverse and vary the camber of the lifting-sail  20 . An upper angle of attack control sheet  38  is attached to the aft end of upper boom  30  and leads along the mast-sprit  44  to the deck  14   d  (not shown) for ease of adjustment. Lower boom  30  may be attached to the luff-spar tack  56  to reverse and vary the camber of the lifting-sail  20 . A lower angle of attack control sheet  58  may be attached to the lower boom  30  and lead to the main deck  14   d  for additional control. Tilt sheet  60  for lifting-sail  20  is also attached to the lower boom  30  and leads aft to the main deck  14   d  for ease of lifting-sail  20  tilt adjustment. Inward canted hydrofoil  18   s  on starboard hull  14   s , and inward canted hydrofoil  18   p  on port hull  14   p  provide the lateral resistance. Directional control is provided by starboard  16   s  and port  16   p  rudders. 
     As shown in FIG. 8, the low aerodynamic drag lifting-sail  20 , or alternatively a lifting-airfoil  22 , may be lowered by a “docking” position apparatus  12  onto the main deck  14   d  with halyard  34   h  from coupling  34  and halyard  36   h  from mast-sprint tip coupling  42 , or the symmetrical airfoil fore-spar  36 , and may be controlled in docking position by tilt sheet  60 . 
     FIG. 9 is an explanatory diagram of a first preferred embodiment of a simplified jib/mainsail aft-mast lifting-sail rig apparatus  6 , an arrangement with dual sails, a jib  20   j  with a mainsail  20   m , are mounted in tandem on mast-sprit  44  in close proximity to one another to gain the same “slot effect” advantage provided by a conventional jib and mainsail. The jib  20   j  and the mainsail  20   m  are each controlled in the same manner with a jib sheet  21   j  and a main sheet  21   m  respectively. The sheets  21   j  and  21   m  are attached to a common lower boom  30 , and lead aloft (not shown) to the mast-sprit  44  and down the vertical mast  50  to the main deck  14   d  for trimming and independently adjusting the angle of attack of the jib  20   j  and the mainsail  20   m . The two adjacent lifting-sails  20   j  and  20   m  may be supported by the low drag mast-sprit  44  stay  52  and aft vertical mast  50  as shown in FIG. 10, with starboard  66   s  and port  66   p  spreaders at the mast maximum buckling stress point  66 , and supporting starboard  64   s  and port  64   p  backstays. Inward canted hydrofoil  18   s  on starboard hull  14   s , and inward canted hydrofoil  18   p  on port hull  14   p  provide the lateral resistance. Directional control is provided by starboard  16   s  and port  16   p  rudders. Aerodynamically shaped, symmetrical airfoil luff-spars  28   j  and  28   m  are attached to or integral with the leading edges of the lifting-sail  20   j  and  20   m  respectively. Universal couplings  34   j  and  34   m  are connected to heads  54   j  and  54   m  of the luff-spars  28   j  and  28   m,  at the middle region of the mast-sprit  44 . The lifting-sails  20   j  and  20   m  are hinged from the mast-sprit  44  with universal couplings  34   j  and  34   m  respectively for unrestricted upward tilting to produce a complete righting moment. Support of the luff-spars  28   j  and  28   m  against fore and aft pitching is controlled, particularly when sailing to windward, by two symmetrical airfoil fore-spars  36   j  and  36   m,  connected between luff-spar couplings  40   j  and  40   m  located in the mid region of the luff-spars  28   j  and  28   m,  and the couplings  42   j  and  42   m  respectively at the forward region of the mast-sprit  44 . In this case, the lifting-sails  20   j  and  20   m  are rotated independently to adjust the angle of attack to the relative wind by rotating luff-spars  28   j  and  28   m  along a line between the luff-spar tacks  46   j  and  46   m  attached to the common lower boom  30  and the mast-sprit-spar universal coupling  34   j  and  34   m  located at the mid-region of the mast-sprit  44 . Tilt sheet  60  is attached to the lower boom  30  and leads aft to the main deck  14   d  for ease of upward tilt adjustment of the lifting-sail  20   j  and  20   m  assemblies. 
     FIG. 11 is an explanatory diagram of a preferred embodiment rotating bi-plane lifting-sail rig apparatus  7 , comprising a biplane with two widely spaced lifting-sails  20  or lifting-airfoils  22  The biplane with dual lifting-sails  20  are spaced widely apart, preferably the length of the luff-spar  28 , to minimize aerodynamic interference and induced drag, while increasing the righting moment with a lowered center of effort. The lower the center of gravity lifting-sails  20  or lifting-airfoils  22  which may be fixed or rotated on vertical mast  50  to a head on lateral bi-plane position (not shown), or to the advantageous “safe leeward position” orientation as shown in FIG.  11 . With the large free area derived-from the widely spaced apart dual lifting-sails  20 , the main trimaran hull  14   t  may be utilized as a crew cockpit, or cabin without interference from the rotating lifting-sail rig. Alternatively, the large main hull  14   t  may comprise an elevated self righting, detachable “life support” capsule or large crew pod  71  with a spaceship-like quality. Ultimate safety and heavy weather multihull operation is achieved with the sea-keeping ability and built in life saving provision. 
     The bi-plane rotary yardarm  68  mounted on the rotary yardarm bearing  69 , supports the widely spaced dual lifting-sails  20  with sail battens  31 , each with a mast-sprit/luff spar head universal coupling  34 , a mast sprit coupling  42 , and a symmetrical airfoil fore-spar  36  connecting to a luff-spar coupling  40 . The widely spaced dual lifting-sails  20  are each controlled by a luff-spar/sail or airfoil tilt sheet  60  attached to the luff-spar tack  56  and leading to the main hull  14   t.  The angle of attack of each lifting-sail  20  is controlled by an upper sail/airfoil angle of attack control sheet  38 , which is attached to an upper wishbone boom  32   w  and leading to the yardarm  68  down to the main hull  14   t.  The rotating bi-plane lifting-sail rig apparatus  7  has a lower center of gravity lifting-sail  20  and center of effort  20   ce  below the fixed mast  50  for easy structural support, handling and balance of aerodynamic and gravity forces. In addition, by lowering the lifting sail force Fs center of effort  20   ce,  the righting moment of the lifting-sail rig may be maximized by moving the keel or hydrofoil  18  force Fr center of lateral resistance  18   clr , as shown in FIG. 1 of the lifting-sail method and apparatus  2 , as far to windward as possible to cancel the overturning moment at a near vertical angle of each lifting-sail  20  for maximum effectiveness. In the case of the rotating bi-plane lifting-sail rig apparatus  7 , the lifting-sail rig  20  heels the multihull to windward moving the center of lateral resistance  20   clr , furthest from the lifting center of effort  20   ce , at the fin or keel  18   s  of a windward ama, or outrigger  14   s  of the trimaran  14   t.    
     FIGS. 12 and 13 are the explanatory diagrams of a first preferred embodiment of a joined dual tandem airfoil lifting-sail rig apparatus  8 , shown with large elevated crew capsule  71  with small surface area, short planing hulls or pods  72  to maximize the planing multihull  70  speed in relatively calm seas. The joined dual tandem airfoil lifting-sail rig apparatus  8 , comprises a dual joined tandem symmetrical lifting-airfoil  24 , where each lifting-airfoil  22  may have a lifting-airfoil forward wing  22   f  with lifting-airfoil rear flaps  22   r,  or as a slotted symmetrical lifting-airfoil  24  a lifting-airfoil middle wing  22   m  would be included. The joined dual tandem symmetrical lifting-airfoil  24  is supported by a horizontal yardarm  68  mounted on a rotary yardarm bearing  69 . The widely spaced joined dual lifting-airfoils  22  are each controlled by a tilt sheet  60  or other means such as tilt motor (not shown) on the yardarm  68  horizontal axis. The angle of attack of the joined dual tandem symmetrical lifting-airfoil  24  about the vertical mast  50  is controlled by the rotation of the lifting-airfoil rear flaps  22   r  on the dual lifting-airfoils  22 . The joined dual tandem airfoil lifting-sail rig apparatus  8  has a lower center of gravity and center of effort  20   ce  below the fixed mast  50  for easier structural support, handling and the balance of aerodynamic and gravity forces. The planing multihull  70  has reduced hydrodynamic drag with an elevated crew capsule  71  and a plurality of three, preferably four widely spaced of short planing pods  72  interconnected in a symmetrical array as shown in FIG. 13, with small hydrofoils  18  for lift control. Small surface area, short planing pods  72  have proven successful with reduced hydrodynamic drag in relatively calm seas, without reliance on large hydrofoils, which may limit the speed with cavitation drag. The righting moment of the joined dual tandem airfoil lifting-sail rig apparatus  8  is maximized by moving the center of lateral resistance  18   clr  of the hydrofoils  18  as far to windward as possible to cancel the overturning moment at a near vertical angle of the joined dual tandem symmetrical lifting-airfoil  24 , i.e. for maximum effectiveness as shown in FIG. 1, by causing the symmetrical lifting-airfoil  24  to heel the planing multihull  70  to windward to move the center of lateral resistance  18   clr  of the keel  18  force Fr of a windward outrigger planing pod  72  furthest from the lifting-airfoil  24  force Fs at the lifting center of effort  22   ce . With the large free area derived from the widely spaced apart dual joined airfoils  22  of the symmetrical lifting-airfoil  24  the planing multihull  70  may include an elevated capsule  71  that may be utilized as a crew cockpit, or cabin without interference from the rotating symmetrical lifting-airfoil  24 . The large planning multihull  70  may comprise a self righting, detachable “life support” crew elevated capsule  71  with a spaceship-like quality. Ultimate safety and heavy weather multihull  70  operation is achieved with sea-keeping ability with a built in life saving capsule  71  elevated above the water surface. 
     FIG. 14 is an explanatory diagram of a preferred embodiment of a delta airfoil aft mast lifting-sail rig apparatus  9  employing an efficient delta shaped sail or wing  23  with a low center of effort  23   ce . The delta lifting-sail or wing  23  is preferably light in weight and may be solid or inflatable similar to conventional delta shaped hang-gliders and kites. FIG. 14 shows the same principle as the aft mast lifting-sail rig apparatus  3  or similarly a reinforced lifting-sail rig apparatus  4  and method of operation, with the embodiments shown in FIGS. 1 through 6, except with a delta shaped lifting-sail  23 . The shorter height of the high lift, delta shaped sail  23  has the advantage of a lower sail force center of effort  23   ce  with a large sail area resulting in a smaller heeling moment with a large sail driving force. The delta airfoil aft mast lifting-sail rig, apparatus  9  may comprise a fixed vertical mast  50  with a short mast-sprit  44  projecting forward at the top of the vertical mast  50  for supporting the delta lifting-sail  23 . The vertical mast  50 , is positioned aft of the delta lifting-sail  23  without aerodynamic interference. The mast sprit  44  is laterally supported by two widely spaced starboard  62   s  and port  62   p  forestays attached to an extended beam planning hull  14 . The aft vertical mast  50  may be supported by two widely spaced starboard  64   s  and port  63   p  backstays (not shown). The center of lateral resistance  18   cr  is located on hydrofoil  18   s  on starboard side of extended beam planning hull  14 , and hydrofoil  18   p  on the port side. Directional control is provided by starboard  16   s  and port  16   p  rudders. The mast-sprit  44  to the delta lifting-sail  23  universal coupling  34  is connected to the to the middle region of the mast-sprit  44  for hinging the delta lifting-sail  23  for unrestricted upward tilting to produce a complete righting moment. Support of the delta lifting-sail  23  against fore and aft pitching is controlled, particularly when sailing to windward, by a substantial guy wire  36   g.  The guy wire  36   g  is connected between a delta luff-sail coupling  40  located in the mid region of the luff-spar  28  and a coupling  42  at the forward end of the mast-sprit  44 . Simple rotation of the delta lifting-sail  23  for adjusting its angle of attack to the relative wind is about an axis defined by a line between the delta luff-sail coupling  40  attached to the leading edge of the delta lifting-sail  23  and the mast-sprit-spar universal coupling  34 . An upper angle of attack control sheet  38  may be attached to the lower edge of the delta lifting-sail  23  and lead to the deck  14   d  A lower angle of attack control sheet  58  may be attached to the lower edge of the delta lifting-sail  23  and lead to the deck  14   d  for additional control. The delta lifting-sail  23  tilt sheet  60  is also attached to the forward lower edge of the delta lifting-sail  23  and leads aft to the deck  14   d  for ease of upward tilt adjustment and for tensioning guy wire  36   g , particularly for sailing down wind. 
     FIGS. 15 and 16 are the explanatory diagrams of a preferred embodiment of the reinforced aft mast midpoint spreader lifting-sail rig apparatus  10  with a biplane rig for a lower center of effort of the sail force and reinforced additional, heavy duty spreaders and stays for offshore cruising. This alternative provides a substantial, seaworthy rig for ocean cruising and racing, with a high resistance to pitch, roll, and yaw to prevent distortion of the biplane lifting-sail  20  rig and resist buckling the vertical mast  50 . The biplane rig is shown in FIG. 16 with a luff spar  28   s  attached to the outer end of a rigid starboard mast-sprit spreader  74   s ′ and a luff-spar  28   p  attached to the outer end of a rigid port mast-sprit spreader  74   p ′, wherein the  74   s ′ and  74   p ′ inner ends are rigidly joined to the mast-sprit  44  to provide the outboard location of the universal couplings  34  for mounting the luff-spars  28   s  and  28   p  respectively. The luff-spars  28   s  and  28   p  are-hinged from said  74   s ″ and  74   p ′ with universal couplings  34  for unrestricted outward tilting to produce a complete righting moment, and pure rotation about their respective luff-spar axes to vary the sails  20   s  and  20   p  angle of attack. The aerodynamically shaped, symmetrical airfoil luff-spars  28  are attached to or integral with the leading edge of the lifting-sails  20 . 
     Support of the luff-spar  28  against fore and aft pitching is controlled, particularly when sailing to windward, by a symmetrical airfoil fore-spar  36  connected between a fore-spar/mast sprint coupling  40  located at the center point of the integral or rigid joint between horizontal spreader spar  74   s ″, and horizontal spreader spar  74   p ″, and a mast-sprit coupling  42  at the forward region of the mast-sprit  44 . A movable symmetrical four-bar linkage, with  74   s ″ and  74   p ″ the fixed link, is created by the connections  34   s ′ and  34   p ′ to  74   s ″ and  74   p ″ respectively. The lifting-sails  20  are rotated to adjust the angle of attack to the relative wind by rotating luff-spars  28  along a line between the luff-spar tack  46  attached to the upper wishbone booms  32   w  and the mast-sprit-spar universal coupling  34  located at the ends of the spreaders  74   s ′ and  74   p′ . For additional control, a lower angle of attack control sheet  58  may be attached to the wishbone booms  30   w  at the lower edge of the lifting-sails  20  and lead to the main deck  14   d.  Tilt sheet  60  is attached to the lower wishbone boom  30   w  and leads aft to the deck  14   d  for ease of upward tilt adjustment, while maintaining tension in fore-spar  36 , particularly for sailing down wind. The angle of attack sheets  38  are attached to the upper wishbone booms  32   w,  leading to the mast-sprit  44  and down the vertical mast  50  to the main deck  14   d  for trimming. 
     The biplane lifting-sails  20  are supported by the low drag mast-sprit  44  with mast-sprit stay  52  and aft vertical mast  50  as shown in FIG. 15 with starboard  66   s  and port  66   p  mast spreaders at the mast maximum buckling stress point  66 , and supporting starboard  64   s  and port  64   p  mast backstays. The reinforced aft mast midpoint spreader lifting-sail rig apparatus  10  has additional support of mast-sprit  44  with starboard mast-sprit spreader  74   s  and rigid port mast-sprit spreader  74   p  on the vertical mast  50 . Lateral mast-sprit stay  75   s  and lateral mast-sprit stay  75   p  are attached to the ends of rigid mast-sprit starboard  74   s  and port  74   p  spreader respectively, to counteract yawing of the mast-sprit  44 . As shown in FIG. 16, a front view of the reinforced aft mast midpoint spreader lifting-sail rig apparatus  10 , the starboard jumper stay  76   s  and port jumper stay  76   p  attached to the rigid starboard mast-sprit spreader  74   s  and rigid port mast-sprit spreader  74   p  respectively, are joined to the vertical mast  50  maximum buckling stress point  28  to counteract pitching and yawing of the mast-sprit  44 . The starboard mast jumper stay  78   s  and port mast jumper stay  78   p  joined at the end of rigid starboard mast spreader  66   s  and rigid port mast spreader  66   p  respectively, are attached to the main deck  14   d  at the mast  50  for additional resistance against pitching and yawing. Inward canted-hydrofoil  18   s  on starboard hull  14   s , and inward canted hydrofoil  18   p  on port hull  14   p  provide the lateral resistance. Directional control is provided by starboard rudder  16   s  and port  16   p  rudder. 
     FIG. 17 is an explanatory diagram of an alternative embodiment comprising a lifting-rotor, known as a Flettner Rotor, may be used in place of a lifting-sail. The lifting-rotor rig generates aerodynamic driving force only when the airfoil cylinder  80  is rotated, or driven about its central axis  84 . Therefore, the driving force is safely controlled by the speed of rotation of rotor  80  even in strong winds. The bent flexible mast rig as shown in FIG. 17 supports the lifting-rotor in the same manner as the lifting-sail. 
     Flexible bent mast-sprit  46  is connected to the upper end of rotor  80  by universal coupling  34  at the rotor axis of rotation  84 . Coupling  40  connects the central rotor ring bearing  79  to the lower end of the fore-spar  36 , while the mast-sprit rotary coupling  42  connects the fore-spar  36  to the forward tip of the bent mast sprit  46 . Lifting-rotor lower bearing  82  is located on the lower end of the rotor  80  at the central axis  84  and connects to the airfoil rotor tilt sheet  60 . Symmetrical airfoil vertical mast  50  is supported by starboard backstay  64   s  and port backstay  64   p.  Flexible bent mast-sprit  46  is supported by starboard forestay  62   s  and port forestay  62   p.  Lifting-rotor end plates  81  may be used to increase the aerodynamic efficiency of rotor  80 . Lifting-rotor drive motor  83  rotates the rotor  80  at the desired velocity about the lifting-rotor axis of rotation  84 . Upper Sail/Airfoil Angle of Attack Control Sheet  38  and Lower Sail/Airfoil Angle of Attack Control Sheet  58  are not necessary. 
     FIG. 18 is an explanatory diagram of an alternative embodiment forward mast lifting-sail rig apparatus  11  comprising an aerodynamic vertical mast  50  mast positioned forward of the low aerodynamic drag lifting-sail  20  with an aft leading mast-sprit  44 . The aft leading mast-sprit  44  is supported by mast-sprit stay  52 , starboard backstay  64   s  and port backstay  64   p.  The vertical mast  50  may be supported by starboard forestay  62   s  and port forestay  62   p . Aerodynamically shaped, symmetrical airfoil luff-spar  28  is attached to or integral with the leading edge of the lifting-sail  20 . The lifting-sail  20  is hinged from the mast-sprit  44  with universal coupling  34  for unrestricted outward tilting to produce a complete righting moment. Universal coupling  34  is connected to luff-spar head  54  of the luff-spar  28 , at the middle region of the mast-sprit  44 . Support of the luff-spar  28  against fore and aft pitching is controlled, particularly when sailing to windward, by substantial guy wire  36   g  connected between a luff-spar coupling  40  located in the mid region of the luff-spar  28 , and a mast-sprit coupling  42  respectively at the forward region of the mast-sprit  44 . The angle of attack to the relative wind is adjusted by rotating luff-spar  28  of the lifting-sail  20  along a line between the luff-spar tack  46  attached to the upper sail boom  32  and the mast-sprit-spar universal coupling  34  located at the mid-region of the mast-sprit  44 . For additional control, a lower angle of attack control sheet  58  may be attached to the wishbone boom  30   w  at the lower edge of the lifting-sail  20  and lead to the main deck  14   d.  Tilt sheet  60  is attached to the lower wishbone boom  30   w  leading aft to the deck  14   d  for ease of upward tilt adjustment, while maintaining tension in guy wire  36   g , particularly for sailing down wind. Inward canted hydrofoil  18   s  on starboard hull  14   s , and inward canted hydrofoil  18   p  on port hull  14   p  provide the lateral resistance. Directional control is provided by starboard  16   s  and port  16   p  rudders. 
     Although the description above contains many specificities, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention, other embodiments and ramifications are possible within it&#39;s scope, modification, and substitution of similar assemblies and parts. Other embodiments may be constructed from and consist of related lifting-sail rigs interchanged with the various disclosed lifting sail and airfoil rigs, apparatus and methods as disclosed.