Abstract: This invention discloses a fin, for use on a surfboard and other watercraft, of a low-drag, high-lift, high-aspect-ratio, low-sweepback-angle planform of symmetrical foil section, with a fit root section that has a forwardly projecting leading edge and cutaway at the trailing edge, alone or in combination with winglets placed on the vertical fin element so as to minimize tip-vortex drag, so as to make the surfboard or watercraft more maneuverable, easier to propel through the water, and to stabilize the surfboard or watercraft.

Abstract: A personal watercraft having improved bottom hull shapes in general, and improved center keel shapes in particular. The center keel can have a substantial section over which the keel angle becomes sharper progressing from front to rear, and the concavities on either side of the center keel become deeper progressing from front to rear. The center keel can have a point of maximum downward slope on either side of the keel centerline, with the maximum vertically downward slope becoming greater with greater rearward distance over a section of the personal water craft bottom hull. The bottom hull can have keel troughs on either side of the keel centerline that become deeper over a section of the personal watercraft bottom hull, traveling from front to rear over that selected section of personal watercraft bottom hull. The center keel shape can provide a smoother ride and improved handling in rough water.

Abstract: A fin box for releasable attachment of a fin to the body of a surfboard or the like; said fin including a fin-tab associated therewith; said fin box adapted for insertion into and retention within said surfboard; said fin box further adapted for reception and releasable retention of a plurality of fin-tab configurations thereby to releasably retain said fin in fixed relationship to said surfboard; and wherein a first surface of said fin box is of a length and a width sufficient to support said fin entirely so that no portion of said fin is in contact with the body of said surfboard or the like.

Abstract: A low profile stabiliser device for attaching to the under surface of a watercraft, typically a surfboard or a boat, including in combination a plurality of stubby keel members joined by one or more transverse members spaced from the bottom surface of the watercraft, the keel members comprising a vertical foremost keel member positioned along the longitudinal centerline of the watercraft trailing keel members on either side of the foremost keel member, the trailing keel members leaning at an angle with respect to the foremost keel member and trailing in staggered formation outwardly towards the rear and sides of the watercraft, the staggered formation adapted to substantially reduce or remove interference to the sideways release of water from each keel member by an adjacent keel member, wherein in operation, one or more of the leaning keel members can be made to approach a vertical position as the watercraft heels over in a turning maneuver.

Abstract: A system for attaching fins to surfboards that utilizes fixing elements embedded in the body of the board, the elements having slots that receive footings extending from the end of the fin. The footings are removably secured by a passive wedge clip fixing system, enabling fins to be removed for transport or upon damage by hand or simple tool. Screws can also be used for attachment.

Abstract: An assembly for converting a non-sailing boat to a sailboat comprises a sailing keel adapted to be removably attached to the keel of a boat, a first and a second support frame, one or more straps connected on a first end to the sailing keel and connected on a second end to one or both of the first and second support frames, a steering support frame, and a rudder attached to the steering support frame or stern of the boat. The first and second support frames and steering support frame are adapted to extend across the boat from one side of the boat to an opposite side, and the first support frame is adapted to support a mast in an essentially vertical position. A method for converting a non-sailing boat to a sailboat utilizing this assembly is also provided.

Abstract: A surfcraft fin system utilizing a rib between fin anchors. The rib sets the distance between the anchors eliminating the need for a manufacturing jig. The rib is removed during the surfcraft manufacturing process resulting in multiple fin anchors adhered into the surfcraft.

Abstract: A device for stabilizing boats and other watercraft that is generally blade-shaped and attaches to the body or hull of the boat. The stabilizing device projects generally outwardly and downwardly from the boat and is pivotally connected along the vertical axis at the attachment point to the watercraft. The device dramatically improves the stability of the boat and resists stops unwanted drift either from a stationary position or from a desired heading.

Abstract: Fin assemblies for a variety of watersport boards including wakeboards, sailboards, surfboards and the like. The fin assemblies include a fin cap, at least one fin base and at least one locking member. Fin assemblies are secured to a watersport board by passing at least one locking member through channels in the board and fin base and into sockets in the fin cap. Fin assemblies are reconfigured by first removing the locking members, arranging the desired combination of fin cap and fin base suitable for current water conditions and/or user ability and then resecuring the fin assembly to the board with locking members.

Abstract: A fin for an recreational device including: a rigid fin core having opposite sides, at least one edge and a base; at least one registration post on each of the opposite sides of the core, and a flexible material at least partially covering the core, wherein the flexible material include leading and trailing fin edges extending outward from the edge of the core and the flexible material is flush with an end surface of each of the at least one registration post.

Abstract: A pivotable deployable bulb mounted foil apparatus for a sailboat can pivot a foil mounted within a keel bulb remotely as needed to provide lateral resistance for the sailboat. The foil or foils can be rotated between a nested position for greater speed when the foils are not needed for lateral resistance in the water to an extended or operative position when needed for lateral resistance. The pivotal bulb mounted foil is especially adapted for use with a canting keel where the sailboat loses its lateral resistance from the keel when the keel is canted.

Abstract: The invention relates to a finkeel (3) for boats, having a fixed part (30) attached to the hull (2) of the boat and a movable part consisting of two lee-boards (32, 33) hinged with respect to an axis lying in the midplane (M) of the finkeel.

Abstract: For eliminating the dynamic drag of the member which supports the ballast by completely enveloping it with a indispensable component of the sailing vessel, namely, the hollow rotatable monolithic rigid hydrodynamic fin, and thereby reducing the dynamic drag of the canoe body when it is sailing. The elongated four-sided symmetrical diamond shaped ballast support is adapted to be fixed to the interior of the canoe body. The top of the rotatable fin enters into the interior of the canoe body so that the water turbulence is substantially less than in the prior art when the top of the rotatable fin is spaced from the bottom of the canoe body. With sliding convex/concave contact, the rotatable fin is laterally supported by the stationary diamond shaped member. A first and second cylinder are fixed to the canoe body sole and canoe body cabin top to provide strong support to the rotatable fin and ballast.

Abstract: A stabilizer for a mobile device includes a first element that has a center-plane and an upper end for attachment to a bottom surface of the mobile device. The stabilizer also has a hollow tubular element that has a center-plane. The hollow tubular element is connected to the first element such that the center-plane of the hollow tubular element and the center-plane of the first element are not aligned.

Abstract: A system for attaching fins to surfboards and other surf craft utilizing plugs embedded into openings in the body of the board, these plugs having slotted openings which receive tapered tabs protruding from the bottom surface of the fin. The tabs are removably secured by engagement springs enabling the fins to be removed for transport or upon damage.

Abstract: A sportboard fin attachment assembly in accordance with the present invention includes a plug that is inserted into the cavity of a socket to define an enclosure. The enclosure is embedded into the underside of a sportboard so that the top wall of the enclosure is co-planar with the sportboard underside. The enclosure includes a tag slot that extends through the top wall into communication with the cavity. The plug has a clamp that forms a pin slot that is oriented perpendicular to the tag slot and is in communication with the cavity. The assembly also includes a fin and a tag that is releasably attached to the base of the fin. Alternate tags having beveled top surfaces are available for attachment to the fin. The beveled surfaces will cause the fin to be inclined at predetermined angles. A tag pin extends outwardly from a tag sidewall. When the tag is moved through the tag slot into the cavity, the tag pin will enter the pin slot.

Abstract: A personal watercraft designed to advance suitably in a forward direction, to prevent an influence of side waves, and to incline to the turning center side when being steered by an operator from a forward direction to a turned direction. The personal watercraft includes a keel provided at a middle portion in the widthwise direction of the bottom of the body and extending from the bow to the stern. The keel is formed in an arc in the widthwise direction of the body. The keel is configured such that, at the rear half portion of the body, the center of the arc of the keel substantially coincides with the position G of the center of gravity of the body. On the other hand, at the front half portion of the body, the radius R2 of the arc of the keel gradually decreases in the forward direction.

Abstract: A shaped hull with a fixed angle keel with respect to the hull that when heeled, orients the keel to an angle of attack substantially related to the heel angle. The angle of attack being sufficient to create on the keel a lateral force substantially equal and opposite to the lateral force derived from the wind. The submerged portion of the hull, however, remains symmetrical and oriented parallel to the course sail as is its associated drag contribution vector. Thereby reducing or substantially eliminating the lateral force generated by the hull and the associated drag contribution. The movement of the shaped hull induces a lateral force on the keel without generating a lateral force and its associated drag on the hull, thus providing a sailboat with reduced drag without resorting to the prior art methods and their associated disadvantages.

Abstract: A slidable, impact absorbing keel device for sailing vessels. A vessel hull and a fin keel are attached to a mutually slidable hull connection member and a slidable keel connection member respectively. A tongue-and-groove connection slidably connects the hull and the keel. A compartment contains a spring and is in fluid communication with the surrounding water by means of a conduit. The keel is displaceable backwards if the vessel runs aground or comes into contact with an object below the water line. The keel will be displaced forward to its initial position by means of the compressed spring. The keel is selectively adjustable by means of a wire and tensioning device for purposes of regular maintenance and trimming the vessel by shifting the keel and thus the vessel's center of mass.

Abstract: A fin-type sailboat keel with a ballast bulb and a single winglet projecting from the after portion of the bulb is disclosed. The after portion of the bulb, to which the winglet is affixed, rotates, allowing the winglet to be canted about the centerline of the bulb 360 degrees. The winglet can have an adjustable angle of attack or a flap at its trailing edge, allowing various effects to be achieved. Mechanisms for the control of these moving parts are described. A fin stabilizer of similar geometry is also claimed.

Abstract: This invention relates to a widened base of a boat keel, notably the base of any keel intended to equip a catamaran-type boat. The skate (3) is prepared separately but mounted and firmly affixed under the keel (2) of a hull (1) by simple means.

Abstract: This invention pertains to a retractable wing keel for sailboats. A keel member is movably attached to the bottom of the sailboat, and a wing member is attached to the bottom of the keel member. In a first embodiment, the keel member is pivotally attached to the bottom of the sailboat and the wing member is pivotally attached to the bottom of the keel member. In a second embodiment, the keel member is slidably attached to the bottom of the sailboat and the wing member is fixedly attached to the bottom of the keel member.

Abstract: A foil having a stabilizing hollow element, the entire foil forming a wing- or fin-like shape. The hollow element may also have a leading edge that tapers to a defined point. The hollow element may also have a foil shape, running substantially parallel to the foil profile of the fin- or wing-like extensions.

Abstract: A sailboat having a novel hull shape, a fixed, shallow keel, dual rudders, and retractable, shallow dagger boards for sailing in shallow or shoal water is provided. The combination of features allows the boat to achieve performance sailing at all points of wind, and in both deep and shallow water. The hull preferably has a hydrodynamic shape which provides lift and lateral resistance to the hull when sailing. The keel is preferably shallow so that the boat may be sailed in shallow water and even beached. The draft of the keel is preferably related to the length of the hull measured along the waterline. In a preferred embodiment, there is 1 inch of draft for every 1 foot of waterline. The boat may also preferably include a set of retractable dagger boards located on opposite sides of the keel. A dagger board may be extended on the leeward side of the boat when the wind exceeds about 15 knots, in order to help prevent side slippage or leeway.

Abstract: A foil having a stabilizing hollow element, the entire foil forming a wing- or fin-like shape. The hollow element may also have a leading edge that tapers to a defined point. The hollow element may also have a foil shape, running substantially parallel to the foil profile of the fin- or wing-like extensions.

Abstract: This is a mechanical element intended to control the rolling of FPSO type petroleum production systems which use adapted decommissioned ships as the floating facility. The bilge keel is made up of two lines of plates, continuous or sectioned, in this case with a small separation between each two adjacent sections, mounted along the bilge of the ship, one on either side, at right angles to the hull, and characterized basically by being wider and having a greater total length than the conventional bilge keels used in ships.

Abstract: An outboard or stern marine drive assembly includes a skeg that is detachably secured to the lower gear case. The skeg plane is laterally off-set from the vertical plane that passes through the propeller thrust axis. One embodiment of the thin, high-strength steel skeg is secured by a "T" section along the top edge of the skeg to mesh longitudinally with a corresponding T slot in the gear case wall. In another embodiment, the skeg is flush mounted to a boss surface cast integrally with the shell wall of the gear case.

Abstract: Cavitation of a hydrofoil element, such as the rudder of a marine vessel, om exposure to a body of water during onset flow at different angles to the chordal axis of the rudder profile, is suppressed by a tab on the lower end tip of the rudder. Such tab has external surfaces thereon which affect flow separation relative to the rudder so as to suppress or delay cavitation.

Abstract: The present invention discloses a limited pivotal fin system 12 for a surfboard 10. The fins self-pivot as the surfboard is turned by the body weight of the user. The pivotal fin system includes an upper stationary mounting portion 18 attached directly to the underside of the surfboard 10, and a lower pivoting fin 12 with a limited rotational pivoting mechanism 16 located in an upper recessed area 28 on the leading edge 26 of the pivoting fin 12. The lower pivoting fin 12 is fixedly mounted to the upper stationary mounting portion 18. The pivoting mechanism 16 comprises an upper 20 and lower plate 32 which are rotably connected 52 to each other and includes a cavity 34 in the upper plate 20 where pins 24 from the lower plate 32 are projected to prevent movement beyond a few degrees. An alternative embodiment discloses a different form of limited pivoting mechanism 54 when the mechanism is mounted directly into the surfboard 10.

Abstract: An asymmetric wing for decreasing the leeward drift of a vessel has two different surfaces, one of which is cambered in cross-section and the other which has less camber in cross-section or flat. The asymmetric wing has a leading edge pointed toward the bow of the vessel and the trailing edge pointed toward the stern of the vessel. The surfaces of the asymmetric wing can be selectively moved to the port or starboard sides of the vessel. For centerboard and sliding keel vessels, a pair of asymmetric wings are installed in trunks, each asymmetric wing having a first cambered surface and a second less cambered surface. The first cambered surfaces of the two asymmetric wings point in opposite directions. At any one time both asymmetric wings are not moved into the water. The asymmetric wing is applicable to vessels without a centerboard or sliding keel trunk. In such a case, a horizontal shaft extends through a single asymmetric wing and the single cambered surface is rotated to either port or starboard.

Abstract: Methods and devices are provided for a water craft, for use on a body of water, having a bottom, and an inflatable keel, coupled to the bottom, wherein the keel contacts the surface of the water during operation of the craft, the keel comprising an inflatable bladder wherein inflating the bladder results in the keel at least partially transitioning from a collapsed state to an inflated state.

Abstract: A watersport board fin has a rigid body element with a leading edge and trailing edge, and a rigid ridge integral with rigid body and extending outwardly from the leading and trailing edges. The ridge has a number of through extending holes formed in it outwardly of the rigid body element, and has an average thickness of about 16-25% (e.g. 18-22%) of the average thickness of the body element, preferably between about 0.1-0.14 cm (e.g. about 0.12 cm). The ridge is substantially completely covered by a flexible material soft enough to minimize injury to a person impacted by it, and flexible enough to be deflected during movement through the water to provide a rudder action. Preferably the flexible material extends along substantially the entire extent of the rigid body element, including the base of the body element, thereby enhancing the safety and rudder performance of the fin. The fin is connected to the bottom surface of a sport board, such as a surfboard, wake board, sail board, water ski, body board, etc.

Abstract: In a surfboard of the type including spaced-apart top and bottom surfaces and an elongated recess formed therebetween for removably anchoring the base of a surfboard fin therein, a shallow draft surfboard fin socket for location in the recess in bonded engagement therewith including an elongated housing including a narrow bottom wall, spaced-apart upstanding elongated side walls, and spaced-apart upstanding short front and rear end walls, all joined together along their intersecting marginal edges to form an elongated cavity configured to receive therein the base of the fin, a flange extending outward from the side and end walls for location between the top and bottom surfboard surfaces, the housing side and end walls extending above the flange a distance sufficient to locate the upper marginal edges of the walls above the bottom surface of the surfboard and, first and second recesses formed in the front and rear housing walls respectively, interior the cavity, for receipt therein of a protrusion, formed at t

Abstract: A keel system for an inflatable kayak which is a one-piece plate of plastic material defining a pressure plate at an upper end, a skeg at a lower end and an attachment portion therebetween. The attachment portion includes upper and lower engaging elements to cooperate with the web and a grommet of a typical inflatable kayak to lock the structure at the stern. A similar device with a keel strip extending rearwardly under the hull is provided at the bow of the kayak. A rudder may be pivotally mounted to the aft edge of a skeg and stern post portion and in turn receive an outboard motor. Locking plate may be extended perpendicularly across the tops of the pressure plates to cooperate with the gunwales and spray cover of the kayak.

Abstract: An articulated fin of the present invention includes a nose section, a tail ection, an upper flexible control surface, and a lower flexible control surface. The upper and lower flexible control surfaces each span from the tail section to the nose section. The fin further includes a gear assembly for applying compressive and tensile forces on the upper and lower flexible control surfaces. The gear assembly bends the tail section upwardly upon applying a tensile force on the upper flexible control surface and a compression force on the lower flexible control surface, and bends the tail section downwardly upon applying a compression force on the upper flexible control surface and a tensile force on the lower flexible control surface.

Abstract: A ship's hull including a first hull part arranged as a hard-chine-hull disposed on a second hull part in the shape of a super-slender float. During in service conditions, only the aft half of the first hull part intersects the water surface so that two separate bow waves develop. By appropriate selection of hull widths and by disposition of the first hull part on the second hull part, the bow waves are in phase opposition. This reduces the wave-induced drag of the ship's hull considerably, especially near the critical speed.

Abstract: A fin box for a water sports board including an elongate socket and a flange which extends laterally from the elongate socket. The socket includes a central elongate cavity and a raised lip about the cavity. The elongate socket also includes an oblong cylindrical outer surface. A ramp extends between the raised lip and the flange. The lip includes a surface to receive sealing tape employed for the laminating process. A set screw assembly provides for locking of a fin within the central elongate cavity. Gussets extending between the flange and the elongate socket provide dimensional stability and locational strength as well as serrations for easy insertion into the foam core of a water sports board. The fin box is able to accommodate positioning within a coating of resin in a socket in the foam core of a water sports board with laminating of the board occurring immediately. The cavity is then exposed through grinding.

Abstract: A fin assembly for mounting to a lower surface of a watercraft hull comprises a base for attachment in a fixed position to a watercraft hull lower surface, the base having first hinge pin receiving bores defining a hinge axis, a fin having an inner end having second pin receiving bores for pivotally securing to the base for pivoting about the hinge axis, and a hinge pin mounted in the first and the second hinge receiving means pivotally connecting the fin to the base, and an elastomeric member disposed between the base and the fin for resisting pivotal movement of the fin relative to the base

Abstract: A rowboat with a pair of permanantly mounted wheels installed in the middle of opposed sides of bottom of boat. A pair of wheel wells isolate the wheels from interior of boat, thereby removing most of the wheels from exposure to turbulance and drag. The wheels are supported by and rotate around an axle. The axle is cradled in a recess molded into bottom of boat. A pair of skegs or keels are molded into boat and aligned longitudinally with direction of wheel travel. Fastened to bottom of skegs is a replacable plastic wear resistant tube split in half longitudinally. Thus providing a rowboat that is easy to move on land as well as water and has significant wear resistance on bottom.

Abstract: A sailboard or surfboard (30) having a fin (32) and a skirt (36) extending aft of the tail edge (34) of the board. The skirt (36) is mounted to the sailboard in a manner so that the skirt assumes the contour of the water when sailed. Adhesive or a clamp plate is utilized to secure the skirt (36) to the board (30). The fin (32) includes a fin base (60) and a foil (62). Foil (62) is positioned aft of the fin base (60) so that the trailing edge (64) of the foil (62) is aft of the fin base (60).

Abstract: A watercraft hull having a lower surface for normal contact with a body of water includes a fin having an inner end secured to the lower surface for extending into a body of water, a hinge intermediate the inner and outer ends for enabling an outer portion of the fin to pivot about the longitudinal axis of the watercraft for enabling increased controllability and performance of the watercraft.

Abstract: A pliant, controllable contour control surface comprising a first flexible facesheet formed to a first initial contour of the control surface, and a second flexible facesheet formed to a second initial contour of the control surface. The first and second facesheets each have a set of prestrained shape memory alloy tendons embedded therein, extending from a leading edge to a trailing edge of the control surface. Each set of the shape memory alloy tendons is separately connected to a controlled source of electrical current such that tendons of the first and second flexible facesheets can be selectively heated in an antagonistic, slack-free relationship, to bring about a desired modification of the configuration of the control surface. A computer based control system is utilized for maintaining a constant temperature of the antagonists to establish conditions conducive to the stress induced transformation from austenite to martensite, accomplished by causing constant current to flow through the antagonists.

Abstract: High performance sailing yacht designs are disclosed based on a keelless sailing yacht concept having dynamic gravitational ballast which is laterally movable for heeling resistance which ballast replaces a function of the standard keel. A keelless yacht of this type is disclosed with an adjustable flap mounted on an elongated strut from which the ballast is suspended below the hull to generate a variable heel hydrodynamic control force independently of the counter-heeling effect achieved by the ballast. The foregoing features enhance the effects of disclosed improvements and modifications to hull design in having a duplex form, with upper and lower hull shapes, the lower of low drag shape, and of reduced section, while the upper hull extends laterally abeam from the lower hull to define reserve buoyancy, added accomodation, and surfaces adapted for hydroplaning when the yacht is at a controlled angle of heel.

Abstract: A tug boat for escort towing and/or harbor use having a towing winch positioned at least on the forecastle. While in escort towing, the tug is intended to improve the steering and arresting properties of a vessel to be assisted by means of a tow rope emitted from the towing winch and connected to the vessel being assisted. In harbor use, the tug boat is applied for ordinary towing and buffer tasks. In order to improve the stability of the tug boat and the towing, steering, arresting and equivalent properties provided with the tug boat in the vessel being assisted, a towing eyelet, through which the traction force of the tow rope connected from the towing winch of the forecastle to the vessel being assisted is transmitted to the tug boat, is positioned depending on the towing angle and in proximity of the deck plane or in the deck plane.

Abstract: The invention provides an improvement in a keel arrangement for a sailboat hull, of the kind having an elongated ballast member spaced below the hull so as normally to extend horizontally and fore-and-aft under the hull, and a front foil and a rear foil depending respectively from a front and a rear portion of the hull, the lower ends of which between them support the ballast member, and in which the rear foil is pivotable about a vertical axis to allow it to act as a rudder. The improvement comprises a joint connecting a main, front portion of the ballast member to a minor, rear portion thereof, the joint allowing both longitudinal and rotational movement between the ballast member portions, whereby the foils can bend independently of each other, and the large majority of drag forces on the ballast member are resisted only by the front foil.

Abstract: A fixed ballast containment unit connected with a ship, comprised of an outer keel shell (16) within which a number of metal hydride containers (18) are supported by internal braces (17) in a manner which provides passages around the metal hydride containers (18) through which a number of heat intermediums may be induced to flow, so that the reactive properties of hydrogen with metal hydrides can be applied to various ships systems, while the mass of the ballast containment unit provides an inertial force to counteract external forces acting on the ship.

Abstract: In a fluid such as water the direction of a vessel is controlled by a fin ving at least one fixed chordwise segment and at least one cantilever mounted movable segment secured to the fixed segment by a backbone or spine spring at the neutral axis, and by differently tensioned control wires that are used to achieve camber variations under the influence of the vessel's control system. An elastomeric skin is supported on stiffeners to maintain the general fin cross section during such camber changes.

Abstract: On a body, for example a stabilizer fin or a rudder blade on ships or the keel fin on sailboats with a keel, which is fastened to a support body, preferably a ship's hull, so that it projects outward, several ribs are fastened so that they project on the exposed end of the body. These ribs are located at some distance from one another and are parallel to the plane of symmetry of the body. The length of the ribs is approximately 1/10 to 1/20 of the length of the body, which eliminates or reduces turbulence which occurs at the end of the wing like structure.

Abstract: A keel assembly for a sailboat includes a base portion which is integrally formed with the underside of the hull of the sailboat, a keel portion which is adapted to be releasably received in assembled relation with the base portion, and a plurality of fastening element assemblies for securing the keel portion to the base portion. The fastening element assemblies include downwardly extending threaded rods which are permanently secured in sealed nonrotatable relation in the base portion. The threaded rods have flanges thereon which are received in nonrotatable relation in recesses in the underside of the base portion. The threaded rods are received and secured in downwardly extending fastening element passages in the keel portion which are accessible through transversely extending access passages in the keel portion.

Abstract: A water ski fin extends through the rear of a water ski. Pivotally connected to a lower portion of the fin is a wing extending substantially perpendicularly from the fin. A linkage is connected to the wing that permits the wing from pivoting until the speed of the fin through the water exceeds a predetermined velocity to pivot and change its angle of attack in response to the speed of the fin through the water exceeding the predetermined velocity.