초록 ▼

An underwater appendage for sailboats, such as a keel or rudder, is fitted with an external shell-like shroud, which is placed around a core portion of the appendage such that the outer shroud forms a deformable water foil which is fastened on both sides of the core near its rear or trailing edge, a

An underwater appendage for sailboats, such as a keel or rudder, is fitted with an external shell-like shroud, which is placed around a core portion of the appendage such that the outer shroud forms a deformable water foil which is fastened on both sides of the core near its rear or trailing edge, and which shroud is everywhere else spaced away from the core. This deformable shroud forms a hydrofoil, the leading edge of which can be displaced to either side of the core by means of inflatable bladders placed on either side of the core, thus creating a desired angle of attack for the deformable foil, either to port or starboard. Inflation of the bladder on the windward side of the boat creates an angle of attack to windward and also a bulging of the shrouded water foil on the windward side creating the desired hydrodynamic lift to counter the lateral component of the aerodynamic force on the sail. As the boat is turned through the wind, onto the opposite tack, the pressure on the bladder is relaxed as it becomes the leeward bladder, and pressure on the opposite bladder is increased as it becomes the windward bladder. Pressure on both bladders can be relaxed when no lift is desired as when running before the wind.

대표청구항 ▼

1. An underwater appendage for a sailboat of the type having a hull and at least one underwater appendage, said appendage comprising: a core portion being substantially keel-shaped having mounting means to said hull, a shell-like foil-shaped flexible outer shroud placed around the said core which sh

1. An underwater appendage for a sailboat of the type having a hull and at least one underwater appendage, said appendage comprising: a core portion being substantially keel-shaped having mounting means to said hull, a shell-like foil-shaped flexible outer shroud placed around the said core which shroud has a rounded front portion descending parallel to the front edge of the core appendage, with free space between the core and the rounded front of the shroud, and with the two sides of said shroud enveloping the opposite sides of said core, with the upper and lower edges of said shroud being essentially horizontal and with the upper edge being close to the bottom of said hull, and the lower edge being nearer to the bottom of said core, with said shroud being disposed such that the sides of the shroud are essentially parallel to the core, and spaced outward from it, such that the distances of the outer shroud sides from said core is substantially constant along a line parallel to the descending axis of said core but which distance gradually diminishes toward the rear descending edge of said core such that the opposite sides of the shroud join their respective sides of the core near the rear descending edge of the said core with there being mounting means for both rear edges of said foil shroud to the said core where said shroud joins said core, forming an outer foil shaped shroud in a position such that the incidence of said foil is substantially parallel to the fore/aft axis of the boat in the undeformed symmetrical condition of said shroud and cross sections of said foil in any horizontal plane having a rounded front incidence portion tapering toward the rear edge such that a hydrofoil shape is formed by said shroud and a space exists between said shroud and the core at all points on the inside surface of said shroud except where it has mounting means along its rear edge where it joins the said core, said mounting means being the only attachment of said shroud such that said spaces provide space for displacing the forward round descending portion of the shroud to either side of said core, and space for the corresponding side of the shroud to displace in the same direction, except for the rear fixed edge of such side, and space for the opposite side of said shroud to displace inward toward said core, creating an incidence angle between the axis of said foil shroud and the fore/aft axis of said boat, and said space receiving variable actuating means for said displacing and for bulging of said shroud on the side which has been displaced outward, and variable actuating means for said bulging and said displacing of said shroud and variable actuating means for flattening the opposite side of said shroud such that an asymmetrical foil shape may be formed, creating lift in the direction in which the foil is both displaced and bulged and reversing means for such actuation in the opposite direction such that the desired hydrodynamic lift may be created on the opposite side of the appendage, said variable means also adjusting the shroud to a symmetrical foil when no lift is desired. 2. An underwater appendage, according to claim 1, wherein the said core is thicker above and below the said upper and lower horizontal edges of said shroud, such that the thicker portion of said core above the shroud extends down to a plane parallel to the said upper horizontal edge of said shroud, said lower horizontal plane of the said thicker portion of said core being only slightly above the upper horizontal edge of said shroud such that sufficient clearance exists for inward and outward displacement of the free upper edge of said shroud but which said clearance will be minimum, and the thickness of said portion of the core will be everywhere defined to form a symmetrical hydrofoil shape, the outer edge of which will be defined by the maximum displacement and bulging of the shroud, said shape of said core tapering toward the back edge where it will be coincident with the back edge of said shroud where said shroud joins said core below said horizontal clearance line, thereby minimizing disturbance of the flow of water along this horizontal line on the appendage, the thicker portion of the said core below the said lower horizontal edge of the said shroud will also be so shaped with minimum clearance for the same purpose. 3. An underwater appendage according to claim 1 wherein said variable actuating means comprises two inflatable bladders between said core and the sides of said shroud near the front of said core, one of said bladders on the port side of said core and the second of said bladders on the opposite side of said core, said bladders each being made of stretchable rubberlike sheet material and each said bladder being comprised of two major sheets, each being substantially rectangular or parallelogram in shape and of the same size, with the two said sheets being closely spaced and joined together along their respective perimeters such that a closed flat bladder is formed, of such size and shape to be placed in the afore said space between said core and said shroud on one side of said core and with the second said bladder being disposed on the opposite side of said core, with means provided for communicating pressure to each of said bladders, said pressures being independently controlled to each bladder such that one or the other said bladder may be inflated such that the said shroud can be displaced and bulged by said pressure, to first one and then the other side of said boat in order to gain lift in the desired direction, or pressure to both said bladders reduced such that said shroud assumes a symmetrical foil shape when no side force is desired on said appendage. 4. An underwater appendage as recited in claim 3 further comprising a plurality of independently controlled additional bladders between said core and said shroud for providing precise control of the shape of the shroud. 5. An underwater appendage according to claim 1 with a layer of high damping material bonded to the surface of said flexible shroud in order to dampen out any undesirable oscillations of said shroud. 6. A sailboat of the type having a hull and at least one underwater appendage, said appendage comprising: a core portion being substantially keel-shaped having mounting means to said hull; a shell-like foil-shaped flexible outer shroud placed around the said core, which shroud has a rounded front portion descending parallel to the front edge of the core appendage, with free space between the core and the rounded front of the shroud, and with the two sides of said shroud enveloping the opposite sides of said core, with the upper and lower edges of said shroud being essentially horizontal, and with the upper edge being close to the bottom of said hull, and the lower edge being nearer to the bottom of said core, with said shroud being disposed such that the sides of the shroud are essentially parallel to the core, and spaced outward from it, such that the distances of the outer shroud sides from said core is substantially constant along a line parallel to the descending axis of said core but which distance gradually diminishes toward the rear descending edge of said core such that the opposite sides of the shroud join their respective sides of the core, near the rear descending edge of the said core with there being mounting means for both rear edges of said foil shroud to the said core where said shroud joins said core, forming an outer foil shaped shroud in a position such that the incidence of said foil is substantially parallel to the fore/aft axis of the boat in the undeformed symmetrical condition of said shroud and cross sections of said foil in any horizontal plane having a rounded front incidence portion tapering toward the rear edge such that a hydrofoil shape is formed by said shroud and a space exists between said shroud and the core at all points on the inside surface of said shroud except where it has mounting means along its rear edge where it joins the said core, said mounting means being the only attachment of said shroud such that said spaces provide space for displacing the forward round descending portion of the shroud to either side of said core, and space for the corresponding side of the shroud to displace in the same direction, except for the rear fixed edge of such side, and space for the opposite side of said shroud to displace inward toward said core, creating an incidence angle between the axis of said foil shroud and the fore/aft axis of said boat; and said space receiving variable actuating means for said displacing and for bulging of said shroud on the side which has been displaced outward, and variable actuating means for said bulging and said displacing of said shroud and variable actuating means for flattening the opposite side of said shroud such that an asymmetrical foil shape may be formed, creating lift in the direction in which the foil is both displaced and bulged and reversing means for such actuation in the opposite direction such that the desired hydrodynamic lift will be created on the opposite side of the appendage, said variable means also adjusting the shroud to a symmetrical foil when no lift is desired.