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US 4,915,048 AGranted
Vessel with improved hydrodynamic performance
AssigneeCorwin R. Horton
InventorUlf H. Stanford
Life of this patent
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AssigneeCorwin R. Horton
InventorUlf H. Stanford
Estimating the term…
Planing vessels of improved performance capability and methods for improving such performance and foils which may be associated with a planing vessels for providing improved performance capability. A dynamic downward force generated as the vessel (1) moves through water, preferably by a foil (3), is imposed on the vessel, with the locus of the force positioned, in the traverse direction, at the longitudinal vertical centerline plane of the vessel. In the longitudinal direction the locus of the dynamic force is positioned, relative to the other forces acting fore-to-aft on the vessel, to decrease the trim angle of the vessel, desirably to less than two degrees. Vessel wetted surface configurations are provided for stable and efficient operation at low trim angles, including the following. A deep draft, fine entrance (32) which minimizes rise at the bow experienced with conventional planing vessels and assists in maintaining laminarity of flow at the planing surfaces. A foil (31) extending along the bowpeak below the waterline and spaced forwardly thereof to streamline the flow passing the bow to thereby decrease spray and turbulence. A skeg (32) extending downward at the bottom of the hull at the entrance along the longitudinal centerline plane which improves directional stability and also assists in maintaining flow laminarity. A sweptback wing located at the entrance, preferably mounted at the lower margin of the skeg positioned with an angle of attack which generates an upward force to improve the vessel stability against pitch and yaw in disturbed water. An aftmidships planing floor (11) having a rise from midships to the stern trailing edge desirably from 50% to 100% of the midships draft improves the stability of the vessel when operated at trim. A release floor (21) extending aftward 5 to 25% of the waterline length of the vessel, preferably from a transverse step (4), and rising over this length 10 to 50% of the midships draft to a transverse trailing edge (22). The trailing edge and the release floor, in the transverse direction, are parallel with base plane of the vessel. The pressure release floor reduces the pressure on the aftward flow to separation at the trailing edge in a gradual and uniform manner which reduces drag. The foil to generate a downward force in the flow desirably is positioned below the stern trailing edge and contoured to produce minimum induced drag and to divert the flow at its trailing edge downwardly so as to reduce turbulence and drag at the stern.
A vessel of improved performance comprising a hull having planing surfaces aft of the entrance capable of generating a substantial dynamic lifting force on the hull, a fine, deep entrance with steeply sloped surfaces capable of generating in the water flow dynamic downward forces on the bow sufficient at speed to counter aftward lifting forces to maintain the hull at a small trim angle and means spaced from said hull and responsive to the flow passing the hull for applying an aftward downward force on the hull with a locus in the transverse direction of the vessel that is substantially at the longitudinal centerline plane thereof, which downward force, together with said dynamic downward force at the bow, is of sufficient at speed to offset a substantial portion of the dynamic lifting forces on the hull, thereby to substantially restrict the rise in the water of the hull caused by the planing forces.
A vessel of improved performance comprising a hull having planing surfaces aft of the entrance capable of generating a dynamic lifting force greater than 5% of the displacement weight of the vessel, a fine, deep entrance with steeply sloped surfaces which generate in the water flow dynamic downward forces on the bow and with surfaces generating lift forces in the water flow being limited in amount and configuration whereby the downward forces generated by the steeply sloped surfaces predominate, at speed, to maintain the hull at a small trim angle, said entrance extending from the fore perpendicular of said hull to and aftward of a fore-and-aft position located at a distance aft of said fore perpendicular equal to ten percent of the waterline length of said hull, the mean draft at said entrance between the fore perpendicular and said fore-and-aft position being at least eighty percent of the greatest draft of said hull aft of said entrance, and means spaced from said hull and located at midships for generating a dynamic downward force, said means comprising a foil mounted below the waterline of said hull, said foil having a chordwise axis generally aligned with the longitudinal direction of said vessel and a spanwise axis generally transverse to said longitudinal direction and said foil being hydrodynamically contoured and angularly positioned about its spanwise axis so that with the vessel moving forwardly through water said foil generates a downward force generally aligned with vertical axis of the vessel of a magnitude to substantially restrict the rise in the water of the hull caused by the planing forces.
A vessel of improved performance comprising a hull having planing surfaces capable of generating a dynamic lifting force greater than 5% of the displacement weight of the vessel and a fine, deep entrance of a generally V-bottom configuration with steeply sloped surfaces capable of generating in the water flow flow substantial dynamic downward forces on the bow, the entrance extending from the fore perpendicular of said hull to and aftward of a fore-and-aft position located at a distance aft of said fore perpendicular equal to twenty percent of the waterline length of said hull and wherein the mean draft at said entrance between the fore perpendicular and said fore-and-aft position is at least eighty percent of the greatest draft of said hull aft of said entrance.
A vessel of improved performance comprising a hull having planing surfaces capable of generating a dynamic lifting force greater than 5% of the displacement weight of the vessel, an entrance having a generally V-bottom configuration with steeply sloped surfaces capable of generating in the water flow dynamic downward forces on the bow and a skeg attached to and extending vertically downward from the keel line at the entrance and extending fore-and-aft along the longitudinal vertical centerline plane a distance equal to at least five percent of the waterline length of said hull, the depth vertically of said skeg being substantially greater than the thickness thereof.
A vessel of improved performance comprising at least one hull having a fine, deep entrance of a generally V-bottom configuration with steeply sloped surfaces capable of generating in the water flow substantial dynamic downward forces on the bow and a forward planing surface facing generally downwardly of said hull and extending fore-and-aft along the keel thereof forward of midships, said surface being elongate in the fore-and-aft direction, being disposed bilaterally symmetrically with the longitudinal vertical centerline plane of the hull and being positioned with an angle of attack in the fore-and-aft direction to generate an upward force when moving through the water.
A vessel of improved performance comprising a hull having planing surfaces capable of generating a dynamic lifting force greater than 5% of the displacement weight of the vessel, including a planing floor extending aftwardly of the point of extreme draft of said hull to a transverse step located, longitudinally, aft of the fore perpendicular of the vessel between 75% and 95% of the waterline length of said hull and, vertically, at or above the extreme draft of said hull and a pressure release floor integral with said hull and extending aftward of said step to the trailing edge thereof at the aft perpendicular, said trailing edge being transverse to the longitudinal centerline plane, parallel to the base plane of said hull and located vertically from the waterline of said hull a distance less than 25% of the extreme draft of said hull, and the surface of said pressure release floor extending in the transverse direction parallel to the base plane of said hull and extending in the longitudinal direction substantially straight or concave to said trailing edge.
A vessel of improved performance, particularly when a dynamic downward force with an aftmidships locus is applied to the vessel during its operation, comprising a hull having a waterline beam at the stern that is about equal to or greater than the waterline beam at midships and having a generally V-bottom floor extending aftward, with a gradually decreasing rise of floor from the base plane of said hull, from the fore perpendicular to a transverse trailing edge at the stern, to form planing surfaces capable of generating a dynamic lifting force greater than 5% of the displacement weight of the vessel, said floor being integral with and fixed to said hull and rising from midships to said stern trailing edge a distance with respect to the base plane of said hull equal to at leat 50% of the draft at midships, said trailing edge extending generally parallel to the base plane of said hull substantially across the waterline beam at the stern.
A vessel of improved performance comprising a hull having a generally V-bottom floor extending aftward, with a gradually decreasing rise of floor from the base plane of said hull, from the fore perpendicular to a transverse trailing edge at the stern, to form planing surfaces capable of generating a dynamic lifting force greater than 5% of the displacement weight of the vessel, said floor being integral with and fixed to said hull and rising from midships to said stern trailing edge a distance with respect to the base plane of said hull equal to at least 50% of the draft at midships, the transverse mean draft between chine lines at a transverse vertical plane 75% of the waterline length of said hull aft of the fore perpendicular is no more than 50% greater than the draft at said plane of the intersection of a straight line between the points of greatest draft at midships and the trailing edge, respectively.
A vessel of improved performance comprising a hull having planing surfaces capable of generating a dynamic lifting force greater than 5% of the displacement weight of the vessel including a planing floor extending to a stern trailing edge thereof which is generally transverse to the longitudinal axis of said hull, a chine line forming an outboard edge of said floor generally parallel with the longitudinal axis of said hull at each side thereof, each chine line extending to a junction with said stern trailing edge, a heel extending transversely outboard to each said junction and having an outboard margin at said junction extending aftward thereof generally parallel to said chine line and upwardly therefrom in a generally curved path to a point above the waterline of the vessel to smoothly separate the flow along said chine line.
A foil having low induced drag having cambered surfaces over a leading portion thereof to provide the capability in flow to generate a force component in a lift direction normal to the chord of the foil and having a lower surface that, beginning from a point about 25 to 55% of the chord length from the leading edge, curves upwardly to a point 85% of the chord length from the leading edge which is a distance from the chord of the foil less than 50% of the distance between the chord and the lower surface at said beginning point.
A method of decreasing the friction and turbulence on a vessel having a hull with planing surfaces aft of the entrance capable of generating a substantial dynamic lifting force and a fine, deep entrance with steeply sloped surfaces capable of generating in the water flow dynamic downward forces on the bow sufficient at speed to counter aftward lifting forces to maintain the hull at small trim angle which comprises imposing on said hull a downward force responsive to the flow passing that at planing force speed, is greater than 1% of the displacement weight of the vessel, at a locus in the transverse direction of the vessel that is substantially at the longitudinal centerline plane thereof and in the longitudinal direction aftmidships.
Dependencies are inferred from the claim text.