Abstract: Hinge apparatus which includes first and second hinge members (12, 14) arranged for relative rotation about a hinge axis (18), and fluidic actuator apparatus (24). The fluidic actuator apparatus includes a force transfer member (22) having a first end attached to the first hinge member at an anchor location spaced from the hinge axis, and expandable pillow (25) apparatus associated with the force transfer member and operative to expand when exposed to a fluidic pressure thereby to apply a force along the force transfer member to the first hinge member so as to cause rotation of the first hinge member relative to the second hinge member in at least a first direction.

Abstract: A hydrofoil wing structure is disclosed to be employed as an accessory for a marine propulsion device, to be disposed above and mostly aft of the propelling means of such a device, to contour and concentrate the kinetic energy in the hydrodynamic vortex created by the propelling means; to reduce turbulence, vibration and noise by reflecting acoustic energy downwardly from the surface of the water; to increase the efficiency of such a device powered by an electric battery; to improve the steering and maneuverability of the vessel by providing a rudder for the device; and to serve as a guard preventing the propelling means from entanglement in vegetation or its damage from submerged objects, and to similarly shield a sonar transducer or other instrument used in conjunction with the device for finding fish or gauging the depth of the water.

Abstract: A wind-propelled hydrofoil comprising a forward assembly with at least partially submerged forward foils and a fully submerged aft foil. The forward foils (43, 44) are such that the resultant of the vertical forces drops when said assembly is translated vertically upwards, with a heave characteristic (F), and increases when said forward assembly is subject to upward pitching, with an incidence characteristic (A). The aft foil (46) has an incidence characteristic (R) such that R(d-g)-Ag+F(g.sup.2 +r.sup.2)>0, wherein d is the distance between the aft foil (46) and the center of heave, g is the distance between the center of gravity and the center of heave, and r is the gyration radius of the hydrofoil.

Abstract: An agile water vehicle for travel above and below the water surface, incls a hull having therein a helmsman's compartment, a payload compartment, and a propulsor unit. A rudder assembly is fixed to the hull and includes a cylindrically-shaped (or slightly tapered) tubular member having a rudder thereon and extending therefrom, the tubular member being rotatable. A wing assembly is fixed to and spaced from a bottom portion of the hull, the wing assembly comprising a pair of wings extending widthwise of the axis of the hull, and a flap adapted for disposal in each of the wings and extendible therefrom, the flaps being operable for pivotal movement upwardly and downwardly from the wings. The propulsor unit, the rudder assembly, and the flaps are operable from the helmsman's compartment. A pair of propulsors are disposed on the wings and are rotatable around the spanwise axis of the wings. A pair of differential flaps are mounted on a rotatable axial cylinder or ring with a fixed divider plate therebetween.

Abstract: A high-speed hydrofoil craft has a hull supported by a foil. When the foil is submerged, the upper surface of the foil may be ventilated by atmospheric air to form an air-filled cavity, in which case the foil performs similarly to a planing foil.

Abstract: Disclosed is a construction applicable to stern drive and outboard types of power boat propulsion units for enhancing the performance normally provided by the customary trim/tilt capabilities designed into the units. At a critical juncture in the trim/tilt operation, the present device automatically "kicks in" and by intercepting only a predetermined portion of the propeller backwash provides an almost immediate stern up/bow down result without noticeable speed retardation. The device lends itself either to kit form or to factory installation.

Abstract: A high speed ship is disclosed which includes a hull structure having a bow portion and a stern portion with the hull being normally supported above the surface of the water when in operation. A forward strut depends from the bow portion of the hull structure and is subtended by a first transverse displacement foil. A pair of midship struts depend from the hull structure aft of the forward strut; the aft struts are subtended by a second transverse displacement foil extending laterally between and connected to each of said struts. The second transverse displacement foil has a beam equal to or greater than its length and provides 70% or more of the major buoyancy for the ship during operation to maintain the hull above the surface of the water during operation. The forward foil provides less than 30% of the buoyancy of the vessel and has a beam less than the spacing between the aft struts.

Abstract: A method and an assembly are provided for mounting a pair of hydrofoils to an outboard engine without drilling holes or otherwise defacing the anticavitation plate of the engine. The assembly includes a mounting plate, an adaptor, and a pair of hydrofoils. The hydrofoils are mountable to the outer edge portions of the mounting plate. In use, the counter-rotation tab of the engine is removed and then replaced by the adaptor. The mounting plate, if not already secured to the adaptor, is coupled to the adaptor. The hydrofoils are then mounted to the opposing edges of the mounting plate. A pair of reinforcing brackets may be secured to the mounting plate such that they extend over the edge portions of the cavitation plate. The forces generated upon the mounting plate will accordingly be distributed to the anti-cavitation plate as well as the adaptor. The hydrofoils employed in the assembly preferably include rudders, which obviate the need for the counter-rotation tab replaced by the adaptor.

Abstract: A watercraft comprises a hull having an upper surface, a lower surface, a bow and a stern. Spaced from the underside of the watercraft at the bow end is a pair of outwardly extending arms rotatably supporting discs. Likewise at the stern of the hull, a pair of arms rotatably supports an additional pair of discs. A multitude of such discs may additionally be provided with bearings. Alternatively, the discs may be mounted upon a ball joint arrangement for rotation and pivoting throughout a preselected range. Each disc is acutely angled from a horizontal reference plane. When the watercraft moves in a forward direction, the discs will rotate. As a result, the relative contact velocity between an underside portion of the discs and the water is substantially reduced as compared to a surface which is fixed to the watercraft. The contact friction is thereby reduced resulting in high speed capabilities of the craft with relatively low powered propulsion units.

Abstract: A sloped hydrofoil (22) is mounted to the bottom of a sailboard or surfboard vertical strut (26) using a hinge joint (24). Hinge joint (24) allows reversal of sloped hydrofoil (22) slope in response to a hull (30) side slip. Efficient sloped hydrofoil (22) supports a portion of craft weight to reduce hull (30) drag.

Abstract: A hydrofoil structures for efficient operation over a wide speed range from subcavitating to supercavitating operation is provided. The dualcavitating hydrofoil overcomes cavitation problems associated with high speed operation of prior art subcavitating hydrofoils by providing a supercavitating profile shape in the lower surface to achieve a supercavitating condition at high speeds, and overcomes performance related problems associated with low speed operation and structural problems associated with high speed operation of prior art supercavitating hydrofoils by providing a profile shape having a robust trailing edge that employs the Coanda effect to achieve a smooth flow exit at the trailing edge. The dualcavitating hydrofoil includes upper and lower surfaces defining a profile that includes a tapered section adjacent to and extending aft from the leading edge and a thick curved section adjacent to and extending forward of the trailing edge.

Abstract: A small waterplane area high speed ship is disclosed which includes a hull structure having a bow portion and a stern portion with the hull being normally supported above the surface of the water when in operation. A forward set of dual struts depend from the bow portion of the hull structure; these dual struts are subtended by a first transverse displacement foil extending laterally between amd connected to each of the dual struts. A second set of aft dual struts depend from the stern portion of the hull structure; the second set of dual struts are subtended by a second transverse displacement foil extending laterally between and connected to each of said struts. The transverse displacement foils provide the major bouyancy for the ship during operation to maintain the hull above the surface of the water during operation. The forward and aft struts and the foils are spaced longitudinally a predetermined distance selected such that the transverse wave created by each corresponding element is 180.degree. apart.

Abstract: A spidercraft supported by a wave rider pod consisting of very large tires and ground effect wings connected to a suspension system to absorb the shocks from planing over rough seas or rolling over rough terrain. It is a craft which possesses at least one hull or cabin, at least one support arm with a suspension system, and at least one flotation tire. The suspension system with springs and shock absorbers allows the wave rider pod to move in concert with the waves or rough terrain while the cabin of the craft remains relatively stable.

Abstract: A universal cavitation plate system for providing an after-market cavitation plate on the lower unit of virtually all boat motors having lower units and propellers. Each universal cavitation plate assembly has a cavitation plate with a longitudinal slot for receiving the lower unit of the boat motor, an elastomeric insert for cushioning or shock absorption between the lower unit and the cavitation plate, and a filler piece for at least partially filling the exposed space of the longitudinal slot between the rear of the boat and the trailing edge of the cavitation plate.

Abstract: A small watercraft powered by twin jet propulsion units, each driven by a respective engine. The engine is concealed within a hatch cover that has a larger portion which is removable for removal of the engine and a smaller portion which is pivotal for servicing of the engine without removing the larger portion. A centrally positioned operator's seat has a seat back with a handle so as to facilitate mounting of a rear deck and facilitate a passenger standing on the rear deck during operation. There are disclosed a pair of driving engines positioned within a V-hull in a central location so as to improve stability and yet permit extreme maneuverability. A fuel tank supplies fuel to the engines and is separated from the engines by a bulkhead with both the fuel tank and the engines being accessible when the smaller hatch cover is opened.

Abstract: The Multiple Concavity Surfing Ship and Transition System is an improvement for a surfing ship that generates a singular water wave and rides on its crest efficiently at high speeds. The improved system now adds provisions to aid in the ship's transition in lifting the ship upwards from its low speed displacement mode deep in the water to its high speed surfing mode on top of the ocean surface and to enhance stability and control during transition and cruise. Two complementary features to assist in this transition are provided, the first comprising one or more pairs of hydrofoils on either side of the ship near its bottom to increase surface area and span to lift the ship upwards at the low speed beginning of its transition, and second, one or more sets of concavities preferably symmetric nested concavities, of increasing camber on the bottom of the ship itself to reduce the wetted area in a controlled manner as the ship approaches its cruise mode at high speeds.

Abstract: The invention is directed to hydrofoil structures for efficient operation over a wide speed range from subcavitating to supercavitating operation. A dualcavitating hydrofoil is provided that overcomes cavitation problems associated with high speed operation of prior art subcavitating hydrofoil structures by providing a supercavitating profile shape in the lower surface to achieve a supercavitating condition at high speeds, and that overcomes problems associated with low speed operation of prior art supercavitating hydrofoil structures by providing an upper surface that combines with the lower surface to form a streamlined cross-sectional shape that achieves a smooth flow exit at the trailing edge for efficient, low drag, high lift subcavitating operation.

Abstract: Hydrofoil watercraft (HFWC)--particularly including extended-performance hydrofoil watercraft (E-P HFWC) characterized by a submerged demi-hull mounting hydrofoils, and also high-performance personal hydrofoil watercraft (P HFWC)--are rendered both tractable and pleasant to operate throughout broad operational ranges by the provision of selective upwards (i) flotation and (ii) planing forces from two sponsons moveable in position at the ends of hinged arms. At their maximally elevated, inboard, positions the sponsons are integrated with the contours of the main displacement hull--preferably a "V"-shape hull--so as to permit the HFWC to operate efficiently and handle well while not on plane, including while cutting through heavy seas.

Abstract: In a catamaran boat, including a propulsion system, and main hull positioned to travel above the water surface, the hull extending longitudinally forwardly, the combination comprising: two pontoons, each spaced below the main hull, the pontoons extending forwardly; support means carried by the main hull and carrying the pontoons, whereby the pontoons are at least mostly submerged below the water surface when the boat is loaded and at rest; the pontoons having associated chines positioned to permit the pontoons to plane on the water surface at typical planing speeds of the boat; the support means having streamlined leading edge structure and upper sponson structure; and the support means having lateral thickness at a longitudinal location spaced at a level above the pontoons and which is less than the maximum width of each of the pontoons at the longitudinal location.

Abstract: A twin-hull boat equipped with a pair of transverse hydrofoils 4 and 5 which are respectively secured to the bottom surface of twin-hull structures 3A and 3B adjacent the stem and stern. A pair of auxiliary wings 6A and 6B are installed opposite to each other at predetermined positions on the internal wall surfaces of the twin-hull structures 3A and 3B mutually facing the hull center line and at a predetermined height between the upper water line formed in the course of low-speed cruising and the lower water line formed in the course of high-speed cruising. The twin-hull boat incorporates a postural angle regulating device 15 to properly regulate the postural angle of the auxiliary wings 6A and 6B by causing them to pivot about a horizontal axis.

Abstract: The present invention is directed to an amphibious boat. The boat includes retractable wheel assemblies secured either side of the boat and movable from a trailering position to a storage position. In a preferred embodiment, the wheel assemblies lock with hydrofoil members secured to the boat hull and effectively transfer loads to the boat hull when the wheel assemblies are in the trailering position. The hydrofoils serve to provide additional lift for the boat when appropriately driven through the water. The wheel assemblies also have a unique suspension arrangement of the wheels for improved trailering characteristics.

Abstract: Apparatus for further improving the efficiency of a propulsion unit having a driveshaft depending from the stern of a boat, while protecting flora and fauna in the water as well as the propulsion unit. A plate member has an upper end adapted to be positioned forward of a driveshaft housing, and to depend downwardly and rearwardly to terminate in a trailing lower end below a propeller. The plate member tapers outwardly along lateral edges from the upper end to the lower end to divert flora and fauna around and under a housing and a propeller attached thereto. A lower portion of the plate member is divided into a plurality of spaced plate-like components defining passageways therebetween to enable water to flow therethrough for more efficient operation of a propeller. At the same time, the forward surfaces of the plate-like components react with passage of water when under way to urge a boat's stern upwardly to a more efficient hull operating position.

Abstract: A hybrid high performance water vessel consists of two hulls: an upper hull with a pair of main fluid-lifting-plane means (called mainfoils thereafter), for providing hydrodynamic lifting force at high speed; and a torpedo shaped streamlined sub-hull disposed beneath the water line, for providing the majority of flotation. Along the water line is a knife-like slender hull called mainstrut that pierces through water surface to minimize the crucial wave-making resistance. The mainfoils are located close to one end section of the vessel, and the sub-hull is placed at the other end section of the vessel, so that the center of hydrodynamic lifting force of the mainfoils and the center of buoyancy of the water vessel is offset substantially along the longitudinal axis of the vessel system. It enables the water vessel of present invention to have a "Hull Inclination" capability that improves the performances of said water vessels.

Abstract: Canard configured hydrofoil sailboards which are normally operated rolled to windward and without yaw and which employ a canard hydrofoil that tracks the water surface are of proven practicality. The present hydrofoil sailboard improves on previous designs by replacing the conventional canard hydrofoil by one of supercavitating type (30), operated in freely ventilating mode. This leads to markedly better surface tracking. This hydrofoil sailboard further improves on previous designs by employing a canard hydrofoil hinged (50,60) so that it can be rolled to one side or the other and locked into the rolled position. The use of a locked, hinged canard hydrofoil leads to a new hydrodynamic force distribution having significant benefits. Among these are improved sail balance which allows conventional sailboard sail and harness arrangements to be used. Additionally, steering by means of board rolling is much improved.

Abstract: A hydrofoil craft has a hull supported above a water surface by a foil connected to the hull by means of a support arm. In accordance with one form of the invention, the support arm enables the foil to move up and down with respect to the hull in concert with upgusts and downgusts of water surrounding the foil so as to maintain the hull at an approximately constant elevation. In accordance with another form of the invention, the support arm is supported by the hull for pivoting about a longitudinal axis extending in substantially the fore and aft direction of the hull. When rolling forces act on the foil, the support arm can pivot about the axis from a vertical position in response to the rolling forces while enabling the hull to remain substantially level.

Abstract: A passively controlled hydrofoil supported planning watercraft having a conventional hull with an integrally formed step. The watercraft includes a centrally located, fully submerged main lifting foil. The main lifting foil is fixed and non-movable, and is attached to the hull along the centerline keel such that its line of action acts substantially through the longitudinal center of gravity of the watercraft. The watercraft further includes a rearwardly located stabilizing foil fixed to a stabilizer strut which is pivotally attached to the stern of the watercraft. A stabilizer strut so attached pivots fore and aft to control watercraft trim angle. Additionally, the stabilizer strut is rotatable about a substantially vertical axis for steering and roll control, and includes a trailing edge upper rudder for yaw control.

Abstract: A retractable step or ladder is mounted to the rear of the personal watercraft. The retractable step has a pair of hollow channel members fixedly mounted underneath the riding platform. An elongated rigid member is mounted to each channel member by springs which permit substantially horizontal travel of each elongated member relative to the channel member until a stop is reached. The springs bias each elongated member into positions where the elongated members are not extended relative to the channel members, however the biasing force of the springs can be overcome by moderate effort of the user of the watercraft who wishes to climb aboard the watercraft from the water. Camming surfaces are formed substantially at the end of each channel member and at the end of each elongated member, and the camming surfaces mate and allow a downward pivoting motion of the elongated members about a hinge pin only when the elongated members are extended until the stop is reached.

Abstract: A novel twin hull boat equipped with a pair of hydrofoils (3) and (4) comprising; a plurality of independently driven auxiliary wings (5/5) and (6/6) respectively being secured to both ends of a front hydrofoil (3) and a rear hydrofoil (4) secured to the bottom of the hull (1); a height sensor (11) for measuring height of the stem form water surface; a pair of inertia sensors or gyroscopes (13A) and (13B) for detecting rolling and pitching angles of the hull (1); a wing-angle sensor (10) for detecting angles of the auxiliary wings (5/5) and (6/6); and a controller (14) for controlling height of the stem constant, preventing the front hydrofoil (3) from coming out of water surface, and also controlling rolling and pitching behaviors of the hull (1) by driving the auxiliary wings (5/5) and (6/6) in accordance with a specific control mode selected by control-mode-setting switches (21) and (22).

Abstract: A number of embodiments of hull arrangements for watercraft that permit forward positioning of the propulsion device but also permit the hull to be constructed as a planing hull. In some embodiments, jet propulsion devices are disclosed and in another embodiment an outboard motor propulsion device is shown.

Abstract: A surfing ship that generates a singular water wave and rides on its crest efficiently at high speeds. Two complementary features to assist in the transition from displacement mode to high speed surfing mode comprise a pair of hydrofoils on either side of the ship near its bottom to increase surface area and span to lift the ship upwards at the low speed beginning of its transition, and a set of symmetric nested concavities of increasing camber on the bottom of the ship itself to reduce the wetted area in a controlled manner as the ship approaches its cruise mode at high speeds. The hydrofoils are retractable, enabling their extension for transition and cruise and their retraction for high speed cruise. Intermediate positions of the hydrofoils also offer the possibility of dihedral to aid in roll stability.

Abstract: Boat propulsion unit, comprising two outboard Propeller drives (3,4), having anti-cavitation plates (7), which are coupled to each other via a tie-bar (10) with a wing profile. In the trim position of the stern drive for low speed, the wing profile has an angle of attack in order to exert a lifting force on the stern drives under the influence of the water flowing past it.

Abstract: A high-speed watercraft provides a fast hydroplane craft, powered by a large gas turbine, that will plane over the surface of the water at high speed using a catamaran-type hull mounted on two long, flat-bottom pontoon skis with water chutes under the back end, with steering done from the front with a combination rudder/water chute. The turbine exhausts through a movable nozzle in the back that can be directed up or down by a hydraulic (or mechanical) actuator towards the surface of the water. The watercraft includes a large high, wide dual tail section having a tail wing and tail flap for control, and a large arch frame over the top from the front to the back with rods coming down to the gunnel to give the hull more strength. The craft also includes a front pontoon ski, a pair of middle pontoon skis, and a pair of aft pontoon skis. Finally, the craft includes a belly plate underneath near the back that acts like an after-ski with water chutes under the aft pontoon skis.

Abstract: Multiple-hull catamaran vessels equipped with hydrofoils have two hulls connected by a deck. Transverse to the hulls below the waterline are three or more hydrofoils, the trim bow and stern hydrofoils, and the relieving middle hydrofoil or a group of hydrofoils. The bow and stern hydrofoils are mounted at a distance not less than 30% and 20% of the hull length to the bow and stern, respectively, from the center of mass. Lift arising on all hydrofoils when sailing at a maximum calculated speed in calm sea reaches 60-70% and in calculated rough seas 20-40% of the catamaran's full weight. The bow foil, middle and stern foils account for 0.05-0.15; 0.15-0.30; 0.10-0.25 shares of the catamaran's full weight, respectively. When sailing in rough sea and during vertical travels of the hulls (vertical rocking), "submergence--emergence" takes place which leads to "increase--decrease" of the lift thereby reducing vertical travel amplitude.

Abstract: A device for permitting an outboard motor boat to operate in shallow water, comprises a first support for securing to a transom of a boat and extending rearwardly therefrom; a keel secured to the first support and extending downwardly therefrom and rearwardly from the transom; a vertically adjustable motor mount for supporting an outboard motor with a propeller housing having a leading surface, the motor mount for positioning the motor in a raised position to permit the boat to operate in shallow water and a lowered position in normal-depth water; and the keel includes a rear edge substantially parallel and adjacent to the leading surface of the propeller housing when the motor mount is in the raised position.

Abstract: Apparatus for improving the efficiency of a propulsion unit having a driveshaft housing depending from the stern of a boat, while protecting swimmers and the propulsion unit. A plate member has an upper end to be positioned forward of a driveshaft housing and to depend arcuately downwardly and rearwardly to terminate in a trailing lower end below a propeller. The plate member tapers outwardly along lateral edges from the upper end to the lower end to divert swimmers around and under a housing and a propeller attached thereto. The plate member reacts to the passage of water when under way to urge the boat's stern upwardly toward a more efficient operating position. The outer corner areas of the upper and lower ends are connected by outwardly curved rods to define a protection zone to protect body parts of swimmers by diverting them outwardly and downwardly under a propeller.

Abstract: A hydrofoil craft according to the invention is provided on the bottom of the hull with at least one, usually several, air cushion recesses arranged along the middle of the bottom in a fore-and-aft direction. The air cushion recesses each forms a groove having the upwardly indented bottom, the upper wall front end, to be deeper and becoming shallower toward the rear end and resembling a triangle or sector in shape when viewed in a longitudinal section and generally to be a rectangle in shape when viewed in a plane. The angle from the shallowest end of the air cushion recess to the deepest end is within 1.degree. to 30.degree. and the two side walls on the sides of the bulwarks of the recess extend a little to the lower parts of the fore-and-aft end walls. The hydrofoils are mounted across the lower parts of the air cushion recesses and are close to the air cushion recesses.

Abstract: A small waterplane area twin hull (SWATH) vessel is disclosed which includes a pair of normally submerged hulls that provide buoyancy support for the vessel. An upper hull platform located above the design water line of the vessel is connected to the submerged hulls by at least two pairs of struts respectively associated with each of the submerged hulls. The submerged hulls are arranged to define an acute angle between them. In one embodiment the vertex of the angle is rearward of the submerged hull and in another embodiment it is forward of the submerged hull. In other embodiments of the invention the struts are arranged to define dihedral angles between the struts and the upper hull platform. In addition, the struts may be angled with respect to the center line of the vessel.

Abstract: A hydrofoil craft which possesses at least one hull, at least one support arm which extends from said hull into the water and which is connected to the hull, at least one foil attached to each support arm, and preferably at least one shock strut per support arm which pivotally connects said hull to the support arm, so that said shock struts allow the support arm and the foil to move in concert with the upgusts and downgusts of water velocity located near the foil so as to enable said hydrofoil craft to maintain approximately constant lift. The principles involved are also applicable to aircraft of the "wing in ground effect" type which is designed to fly close to the water's surface so as to take advantage of the favorable aerodynamic effects of the water's proximity.

Abstract: A hydrofoil sailboard comprising a conventional sailboard, without the usual tail skeg, equipped with two hydrofoils arrayed in a canard configuration, the combined lift of the foils being sufficient to hold the board clear of the water at operational speeds. The main foil, mounted beneath the rear of the board is designed to ride fully submerged and to support the bulk of the weight of the board and sailor. The much smaller canard foil, mounted beneath the front of the board is designed to ride at or near the water surface, and its purpose is control and balance. The main foil is connected to the board by a supporting foil which is provided with ventilation fences. The canard is rigidly connected to the board by a support comprising a rod about which a streamlined fairing is free to swivel. A seal between the fairing and the rod prevents airflow to the canard along the inside of the fairing.

Abstract: A hydrofoil stabilizer for a marine craft employing an outboard or inboard/outboard motor. The stabilizer is specially shaped to have a central position adapted to attach to an existing cavitation plate of the motor, two upwardly sloping portions the angles of which approximate the bottom of the marine craft, and two peripheral portions adapted to improve the stability of the craft by running in relatively less turbulent water away from the immediate vicinity of the propellor. The stabilizer improves the turning and tracking characteristics of the craft.

Abstract: The invention provides an improved SWATH type vessel having pontoons and a stern plane located in a position to influence water flow in the region of the tail cone portions of the pontoons and the propellers to reduce depression of the water adjacent the propellers which would otherwise cause propeller ventilation when the vessel is moving at speed.

Abstract: A catamaran includes a pair of floats, a deck extending in the air between the pair of floats as fixedly attached thereto and a connecting member extending in the water between the pair of floats as fixedly attached thereto. The connecting member has an airfoil-shaped section so that a lift is provided to the bow of the catamaran while it is cruising. Preferably, the airfoil-shaped section is inclined to define an attack angle in a range between 15 degrees and 25 degrees and most preferably approximately at 20 degrees. When applied to a working catamaran having a rotating impeller for collecting floats, a tail section is provided as extending downstream from a downstream edge of the air-foiled section.

Abstract: A catamaran comprises two single hulls arranged in parallel in the spaced relation to each other, and a deck for connecting the two single hulls, the single hull having a semisubmerged portion and a connecting portion for connecting the semisubmerged portion to the deck, the semisubmerged portion having a maximum width portion where the width of its vertical transverse cross section is largest at a position near the water level, the width of vertical transverse cross section of the semisubmerged portion abruptly decreases upward in the vertical direction from the maximum width portion and gradually decreases downward in the vertical direction from the maximum width portion, the semisubmerged portion having a minimum width portion where the width of vertical transverse cross section becomes smallest after it abruptly decreases upward in the vertical direction, and the width of vertical transverse cross section of the minimum width portion is 60% or less and 30% or more of the width of vertical transverse cross

Abstract: A water sports device for supporting a seated human rider while the rider and the device are towed behind a powered water craft,, including an elongate board to which a seat and foot holder are secured, an elongate arm extending downward from the board and a planing blade secured to the arm generally parallel to the board so that the planing blade provides essentially no lift when the board is horizontal. The positioning of the seat and the planing blades at the rear of the board, the use of a single vertical strut, the size of the planing blade and the positioning of the foot holders at least two feet in front of the seat provides a water sports device which is relatively easy to ride,, while at the same time being highly maneuverable and capable of high jumps.

Abstract: A hull for a water-borne vessel includes submersible variable displacement ods attached to a main hull of the vessel through pivotable arms which allow positioning of the submersible pods at locations within a range of horizontal and vertical locations. The variable displacement pods also include hydrofoils and other controllable surfaces to provide dynamic lift and attitude control of the vessel. A gearing arrangement is provided to maintain or selectively change the orientation of the pods or portions thereof at different angular positions of the pivotable arms. Support for the vessel can thus be controllably proportioned among both static displacement and dynamic lift of the main hull and the variable displacement pods as well as through dynamic lift of foils or planes.

Abstract: A hydrofoil for watercraft is provided. The hydrofoil includes a generally flat body including an upwardly extending wing for providing low speed torque control and rudders extending from the bottom surface of the body to provide high speed torque control. The hydrofoil is adapted for mounting to an anti-cavitation plate. The depth of the hydrofoil can be controlled through the use of shims or a bracket including an offset arm to which the hydrofoil is mounted. The angular position of the hydrofoil is adjustable in the horizontal plane, thereby allowing the rudders to compensate for the lateral torque produced by a propeller.

Abstract: A hull extension is attached at an appropriate distance above the hull bottom surface to the stern of a planing water craft so as to be at least partially submerged at subplaning speeds and totally unsubmerged at planing speeds, effectively increasing hull length at subplaning speeds while not affecting hull length at planing speeds. A "step" effect is thus featured whereby the hull extension is not in contact with the water once planing commences. Hydrodynamic and buoyant efficiency is increased by the hull extension at subplaning speeds and unaffected thereby at planing speeds. The hull extension also offers practical utility in terms of providing additional protection, deck space and mounting area.

Abstract: A permanently fixed metal trim tab for attachment in pair combinations to the aft end of a boat. Each trim tab comprising a downwardly extending aft edge. A top surface of each trim tab comprises an aft area which comprises striations which provide an anti-slip surface. The strength, position of attachment to the boat, and anti-slip surface permit use of the trim tab as a step for entry and exit to and from the boat. Each trim tab comprises a flange for attachment to a transom of the boat from connecting points above and below an aftwardly extending substantially flat plate of the trim tab which is an integral part of the flange. The trim tab comprises a uniform cross section which is compatible with fabrication by an extrusion process.

Abstract: A lightweight, high strength, water ski hydrofoil assembly includes a diamond planform hydrofoil wing and a V-strut connecting the wing to a parallel ski support platform. The diamond planform wing is formed as a unit and the separately formed V-strut and platform secured thereto. The wing is provided with a foam plastic, aluminum or composite core element, while the V-strut and platform are provided with core elements selected from aluminum or aluminum alloys, composites and balsa wood. In the preferred embodiment, the core elements are provided with an intermediate layer of molded composite material (resin impregnated fiberglass and graphite fibers, or cloth) and an outer layer of rubber. The rubber coating may be applied to the core elements by injection molding, and confined to the leading and trailing edges of the components, with the intermediate layer being omitted, in some embodiments.

Abstract: A watercraft performance type device for facilitating the on-plane operation of a watercraft comprising a plate-like member which is specifically designed to be removably attachable to the underside portion of the cavitation plate associated with the lower drive unit of a typical outboard motor or stern drive assembly, the plate-like member including an angularly related tab portion extending downwardly substantially across the rear end portion thereof, an opening strategically positioned for receiving the downwardly extending torque tab commonly associated with most cavitation plates, the torque tab opening being located and dimensioned so as to enable the torque tab to extend therethrough when the plate-like member is attached in operative position to the underside portion of the cavitation plate, and a cut-out arrangement associated with the front end portion of the plate-like member for positioning and locating the same in close abutting relationship with that portion of the lower drive unit located adjac