Ships – Sail or control means therefor
Reexamination Certificate
2002-07-01
2003-12-16
Morano, S. Joseph (Department: 3617)
Ships
Sail or control means therefor
C114S039130
Reexamination Certificate
active
06662738
ABSTRACT:
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'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 appa
Morano S. Joseph
Olson Lars A.
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