Abstract: An integrally formed fibreglass fin assembly (1) including a base (2)—that is defined by broken lines (3,4)—for mounting the assembly to an object in the form of a surfboard (5). A primary fin (6) extends upwardly from base (2)—in that it extends upwardly from line (3)—and has a compound arcuate leading primary edge (7) and a compound arcuate trailing primary edge (8). A secondary fin (9) extends rearwardly and upwardly from base (2)—in that it extends from line (4)—and has a compound arcuate leading secondary edge (10) and a compound arcuate trailing secondary edge (11).

Abstract: The three-degree of freedom fin apparatus and method described herein is for use on a watercraft (such as a surfboard) and allows adjustment of up to three degrees of freedom, including a translational degree of freedom along a longitudinal axis of the fin structure in the fore and aft direction (longitudinal translation or pitch), a first rotational degree of freedom about the longitudinal axis (roll), and a second rotational degree of freedom about a vertical axis centered at a point on the fin (yaw). Pitch adjustment is made by sliding a base plate and fin assembly along the longitudinal axis. Yaw adjustment is made by moving a front portion of the fin assembly about a yaw pivot point and the rear portion along a yaw track in the base plate. A roll adjustment is made by rotating a fin unit of the fin assembly about the longitudinal axis.

Abstract: FIG. 1 is an exploded view of the invention that consists of a reusable installation guide or router template, (13), which also doubles as a resin dam to secure receptacle, (9), into substrate (19)-(20). Insert (3) resides in receptacle, (9), and accommodates fin, (1), in angled slot (4). The insert, (3), and fin (1), are secured via grub screws, (10), tightened by Allen key (11). This design will accommodate a wide variety of proprietary fins available from numerous manufacturers who bundle their fin mounting systems to be used only with their fins. The fin can be removed, moved laterally within the slot, and canted by changing the insert. The fin is not part of the instant invention.

Abstract: An adjustable fin system for a watercraft such as a surfboard, includes a fin having a base, a foot extending from the base, a fin box mountable within a hull of the watercraft and a manually operable detent mechanism for releasably holding the fin in a plurality of different positions relative to the fin box. The fin box defines a cavity for receiving the foot. The cavity has an opening on a first surface through which the foot is inserted. The opening and the base are relatively dimensioned so that when the foot is received within the cavity the base substantially covers the opening.

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 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: A wave riding surfing board with a pair of transversely oriented hydrofoils, each attached to respective front and rear struts, for supporting a surfer in a prone or kneeling position. In operation, the front canard hydrofoil is arranged for piercing the surface of the water and partially supporting the weight of the rider and the board, while the fully submerged rear hydrofoil is arranged for supporting the remaining 90–100 percent of the weight. The rigging angle of the front canard hydrofoil can be adjusted. The surfing board can be maneuvered by banking the board. In a preferred embodiment, a pair of control handles and a control mechanism give rider a control over the front canard hydrofoil and the flap surfaces on the trailing edge of the rear strut to enable precision maneuvering.

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: Apparatus is provided for attaching a fin to the underside of a small watercraft, such as a surfboard. The apparatus includes a holder which is attachable to the underside of the surfboard, so that a recess defined in the holder extends inwardly from the underside. The apparatus further includes a fin sub-assembly comprising a fin and a body which is receivable within the recess defined in the holder. The fin sub-assembly can be received in the holder in a plurality of angular orientations about an axis generally perpendicular to the underside of the surfboard. The invention extends to a holder, a small watercraft, and a method for attaching a fin to an underside of a small watercraft.

Abstract: A sailboard has a pair of skegs extending downwardly from a bottom surface thereof generally adjacent a rear of the sailboard. The pair of fins extend in a vertical orientation parallel to a centerline of the sailboard. A retractable fin is mounted adjacent the rear of the sailboard. The sailboard has a mast base adjacent an aerodynamic center thereof. A tunnel area is formed at a bottom surface of the sailboard adjacent the rear of the sailboard between the pair of skegs.

Abstract: A sports board with an expanded foam core that has a density adapted so the core will receive a solid sheet skin laminated directly thereto without an adhesive layer. The sports board includes a bottom solid sheet skin laminated directly to a bottom surface of the expanded foam core, and a foam top skin laminated to a top surface and heeled to side surfaces of the expanded foam core.

Abstract: The surfboard fin, in particular, a long surfboard fin has been fixed to or removed from the surfboard under application of a washer and a screw. This operation is quite inconvenient and the fin is removed or fixed when the surfboard is used or is not used, resulting in that the prior art fin has required a quite amount of labor for it. The present invention enables this operation to be carried out manually in an easy manner. The box is fixed to a groove formed at the surfboard with adhesive agent and then the inside part of the box is formed with two grooves standing at different levels. The front long groove is positioned at a slight higher location and one pin of the fin can be inserted into the groove. The rear part pin can be inserted into several L-shaped grooves arranged at a slight lower part of the rear part of the box.

Abstract: A surfboard fin is fixed when it is used, and removed when it is not used. If the fin is not removed when the fin is not used, it produces an inconvenient state during transportation of the surfboard and the like. However, at present, certain screws are used for its fixing or removing. This work requires much amount of labor and a surfboard playing person feels much inconvenience for this work. The present invention provides a method capable of easily fixing a fin to or removing a fin from a surfboard manually. A rectangular groove is formed at the surfboard, a fitting box is embedded into the groove and fixed with adhesive agent. An inner groove is formed at the central part of the box, the inner groove has two protrusions at right side and two protrusions at left side at the side parts. When the fin is set in the inner groove, the two fitting grooves of respective the right and left sides are provided at the legs of the fin, fitted to the protrusions of the inner groove, whereby the fin is fixed.

Abstract: Disclosed is a device disposed in one of a plurality of holes on a body of a surfboard for fixing one of a plurality of fins therein, each fin including an elongated tab extended downwardly, horizontally from a base thereof, the tab including a plurality of spaced protrusions on its either side. The device comprises a central, lengthwise slot including a plurality of spaced projections on its either side above its bottom, wherein responsive to inserting the tab into the slot, the tab is adapted to move rearward by snappingly pushing until the tab is stopped by a rear end of the slot with upper surfaces of the protrusions engaged with lower surfaces of the projections. Either assembly of the fins without sacrificing its fastening or disassembly thereof can be made easy.

Abstract: A dynamic fin system (DFS) achieves fin rotation passively via water flow so that no direct active control of fin rotation is required by the watercraft operator. The DFS, using a combination of fin rotation via at least one axle and resistive forces applied to a fin mounting tab, provides an assembly in which a fin can pivot from side to side in a reliable, effective and simple way. The DFS provides ease in turning and stability at a neutral position while minimizing the amount of flow resistance. The DFS provides a strong fin mounting, and uses a combination of an axle for rotational control, a resistive centering force, and a force preload for stabilizing the fin in the neutral position. The DFS provides a mount for a rotating fin in a watercraft hull that supports repositioning of the rotating fin axis both forward and rearward in the hull.

Abstract: A fin assembly for adjustably coupling a fin (2) to a board (16). The fin assembly includes a fin having a base (6), the base including a substantially semicircular portion (13) and a front tip (12). The fin assembly also includes a fin box (1) adapted to be attached to a board, the fin box having an opening (3) for receiving the base of the fin. A rear end of the opening has a substantially semicircular portion (5) for receiving the semicircular portion of the base. A front end of the opening has a plurality of rifts (4) for selectively receiving the front tip of the base. Changing the rift that the front tip is disposed in changes an angle of attack of the fin. The fin assembly also includes a fastening assembly (7, 8, 9, 10, and 11) for removably securing the fin to the fin box.

Abstract: Provided is a system including a fin box that allows surboard fins to be installed, removed or adjusted to the front or rear of the board within the box and a means for installing the box on the surfboard. More importantly, the fins can be installed in the fin box, and adjusted or removed from the fin box without the use of tools. By using the fin box installation system, manufacturers can effectively locate, align and install the fin box on the surfboard. More importantly, the manufacturers are able to lean and rotate the fins precisely at any desired angles and achieve precise and critical symmetrical mounting of the fins with relation to the centerline of the surfboard.

Abstract: A curved lower surface of a gliding board, such as a wakeboard or a surfboard, is provided with an anticlastic shape to resemble the shape of a saddle. The lower surface of the board is concave in a transverse cross section and convex in a longitudinal cross section along the entire length of the board.

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 pivotal fin system, for use with an aquafoil, such as surfboards, body boards, wave skis, sail boards, wake boards and the like, comprising a pot (3) and a fin (2), having a tab (18) extending from the base (17) of the fin (2). The pot (3) has a central slot (11) and is mounted in the board (23) with the opening of the central slot (11) flush with the board (23). The slot (11) has a releasable locking means (6 & 7) therein, and the tab (18) has a connection means (21 & 22), which is releasably engaged by locking means (6 & 7). Preferably the releasable locking means (6 & 7) is a substantially c-shaped clamp, and the connection means (21 & 22) has a recess or recesses (22) behind a bulbous extension (21), which is engaged in the c-shaped clamp, with arms (5) of the c-shaped clamp engaging in the recess or recesses (22).

Abstract: A fin for a watersport board, such as a surfboard, includes a substantially rigid core covered by a flexible core covering. The core may include one or more positioning members located on either side surface of the core. The core covering may be formed over the core without covering the positioning members. The fin may include a board coupling assembly that includes a plurality of plugs that each have a lumen lined with material of the flexible core covering. The board coupling assembly may secure the fin to the board by compression forces between a screw and the lining of the plug lumens. Methods of making and using such a fin are also disclosed.

Abstract: An adjustable fin insert assembly is disclosed for mounting on a cavity of a wake board, and includes a fin box positionable in the cavity of the board. The fin box is elongate and includes a longitudinal slot which extends into the fin box from a lower surface thereof. The assembly includes a fin member removably mountable on the fin box adjacent the slot with a portion of the fin member extending into and being slidable along the slot for permitting adjustment of a position of the fin member in the slot. The assembly also includes a plurality of positioning members positioned in the slot and being longitudinally slidable in the slot. A space is defined in the slot adjacent to at least one of the positioning members, and the space is repositionable in the slot by sliding the at least one of the positioning members.

Abstract: An adjusting fin for a watercraft consisting of a fin removably attached to a spindle that is held within a fin box. The spindle is rotatable within the fin box such that the fin can pivot with action of water against the fin as the watercraft moves through the water. Adjustable stops act against cams on the spindle to limit the range of rotation available, thus allowing the adjusting fin to be set up to suit the prevailing conditions and the expertise of the user. An optional biasing means biases the fin towards a neutral position which is perpendicular to an underside of the watercraft.

Abstract: Apparatus is provided for attaching a fin to the underside of a small watercraft, such as a surfboard. The apparatus includes a holder which is attachable to the underside of the surfboard, so that a recess defined in the holder extends inwardly from the underside. The apparatus further includes a fin sub-assembly comprising a fin and a body which is receivable within the recess defined in the holder. The fin sub-assembly can be received in the holder in a plurality of angular orientations about an axis generally perpendicular to the underside of the surfboard. The invention extends to a holder, a small watercraft, and a method for attaching a fin to an underside of a small watercraft.

Abstract: “CONSTRUCTIVE DISPOSITION OF ADJUSTMENT OF THE REMOVABLE LATERAL FINS IN SURFBOARD” that, besides conserving the removable fins and the possibility of the central fin when of the use of the usual disposition of three fins in the surfboard to fit longitudinally, has innovated by providing to the surfboard lateral fins (2) specific base (5) the possibility of, by juxtaposition to the fitting cup (1), endowed with opening or incision (3) with graduate rifts (4) in it tip front, to adapt the fin (2) to the user's need, with multiple angular tuning options to the sides, guaranteeing to the surfers the possibility to adapt the surfboards to their own ability degree in the surf practice, as well as to the marine conditions, without for so being compelled to obtain different types of boards.

Abstract: A fin plug assembly to receive and engage a fin includes a cavity, a cam with gears, and a worm gear. The fin plug assembly allows a quick and easy fore-aft adjustment of the fin. Disclosed also is a method of installing the fin plug assembly in a surfboard using a one-piece complete control jig system including the step of providing additional structural strength by removing and/or spiking the foam material in the body of the surfboard.

Abstract: A water floatation board includes a pair of curved side fins for an increase in holding power of the board when in the matter, and without increasing drag during board use. Each curved side fin has a concave surface that faces a centerline of the board, and a convex surface that is opposite of the concave surface. The inner and outer surfaces merge to form leading and trailing edges, and a fin tip. The use of the concave surface allows the fin area to increase without an increase in fin depth, thus providing greater holding power without increasing drag.

Abstract: A fin plug assembly to receive and engage a fin includes a cavity, a cam with gears, and a worm gear. The fin plug assembly allows a quick and easy fore-aft adjustment of the fin. Disclosed also is a method of installing the fin plug assembly in a surfboard using a one-piece complete control jig system including the step of providing additional structural strength by removing and/or spiking the foam material in the body of the surfboard.

Abstract: A fin and tag are formed from a unitary structure. The tag releasably secures to a tag engagement member embedded in a sportboard. A tag-pin extends through the tag about perpendicular to the longitudinal axis of the tag with first and second tag-pin ends extending outward from the tag. The engagement member has a longitudinal center slot for receiving the tag, and at least one bilateral slot intersecting the longitudinal center slot for allowing passage of the tag-pin as the tag is inserted in the center slot. The first and second tag-pin ends are respectively secured in first and second clamping engagements disposed on opposite sides of the center slot. Each clamping engagement is suspended by opposing flexible anti-torsion suspension members, and has elongated upper and lower clamping members between which a tag pin end is secured. Each clamping engagement is tightened and loosened by a cap screw and T-nut engagement.

Abstract: A recreational device for supporting a person being pulled along over the surface of a body of water, including an elongated platform body having a central front-to-rear axis and terminated by a slightly upturned, rounded front end, a rounded rear end, and a pair of spaced-apart side edges extending therebetween to form a smooth transitional periphery having rounded corners at the front and rear, the platform body further including a top surface for contact with the feet of the person and a bottom surface for contacting and moving over the surface of the water, two widely spaced-apart upwardly concave channels formed in the platform bottom surface adjacent the side edges and extending parallel to the central front-to-rear axis and terminating respectively in front of the rear end and in back of the upwardly turned front end, and a concave area located on the platform top surface, between the channels, to provide different elevations in the platform top surface for the person to place his or her feet and regul

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 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 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 bottom fin for a watersports board such as a surfboard or a windsurfer board. It has an upper body portion having a leading edge that extends downwardly and rearwardly from its front end. The bottom fin also has a lower body portion having a leading edge that extends downwardly and forwardly from the bottom end of the leading edge of the upper body portion. The upper body portion and lower body portion have a trailing edge that extends downwardly from the rear end of the top edge of the bottom fin all the way down to its bottom end. An elongated bulbous member is connected to the bottom end of the fin. There are attachment lugs extending upwardly from the top end of the bottom fin for securing the fin to the bottom surface of a watersports board.

Abstract: A hydrodynamic device for use with a recreational water vessel such as a surfboard, disrupts a flow of water under the recreational water vessel. A channel member (12) and a fixing device (14) are attachable to an underside of the recreational water vessel. The fixing device (14) may have lugs (44) arranged to be received in corresponding recesses in the underside of the vessel. Water flowing between the underside of the vessel and the channel member (12) passes from a high water-pressure zone to a low water-pressure zone, which enhances forward thrust of the recreational water vessel in the water.

Abstract: A t-shaped, hydrodynamic fin (“t-fin”) for surfboards designed to maximize performance and maneuverability of the surfboard by creating, in conjunction with two vertical side fins, two chambers to funnel and control the flow of water. The crosspiece of the t-fin is parallel to the surfboard and is horizontal when the surfboard is level from side to side. But also functions as a vertical fin when the board is tilted sideways (in either direction) and the side fins lose their verticality. The t-fin enhances surfboard maneuverability by maintaining fin perpendicularity on the board at all times. The t-fin is fastened to the underside of the surfboard, at the stern, but a second t-fin may be fastened at the same time to the bow underside, to achieve a surfboard that can be used reversibly. T-fins are custom-made, shaped and contoured, and the crosspiece of the t-fin affixed, to achieve the desired hydrodynamic effect.

Abstract: A bottom fin for a watersports board such as a surfboard or a windsurfer board. It has an upper body portion having a leading edge that extends downwardly and rearwardly from its front end. The bottom fin also has a lower body portion having a leading edge that extends downwardly and forwardly from the bottom end of the leading edge of the upper body portion. The upper body portion and lower body portion have a trailing edge that extends downwardly from the rear end of the top edge of the bottom fin all the way down to its bottom end. An elongated bulbous member is connected to the bottom end of the fin. There are attachment lugs extending upwardly from the top end of the bottom fin for securing the fin to the bottom surface of a watersports board.

Abstract: A fin and tag are formed from a unitary structure. The tag releasably secures to a tag engagement member embedded in a sportboard. A tag-pin extends through the tag about perpendicular to the longitudinal axis of the tag with first and second tag-pin ends extending outward from the tag. The engagement member has a longitudinal center slot for receiving the tag, and at least one bilateral slot intersecting the longitudinal center slot for allowing passage of the tag-pin as the tag is inserted in the center slot. The first and second tag-pin ends are respectively secured in first and second clamping engagements disposed on opposite sides of the center slot. Each clamping engagement is suspended by opposing flexible anti-torsion suspension members, and has elongated upper and lower clamping members between which a tag pin end is secured. Each clamping engagement is tightened and loosened by a cap screw and T-nut engagement.

Abstract: A surfing craft with removable fin. A removable fin is disposed in a fin box and the fin box is disposed in a surfing craft body. A releasable locking mechanism has a spring actuated locking arm, a locking tab and an indention. The spring actuated locking arm applies spring force for locking the locking tab into the indention. A counter force is applied to the spring actuated locking arm to remove the fin from the fin box. In one preferred embodiment, the locking tab is attached to the locking arm and the locking arm is bendably connected to the fin. In this preferred embodiment the indention is on the fin box and the locking arm's locking tab is engaged with the indention of the fin box to prevent the fin from disconnecting from the fin box. Also in this preferred embodiment, by applying finger force the locking arm is bent causing the locking tab to disengage the indention so that the fin can be removed.

Abstract: A rudder construction for use particularly in light vessels, for example, in kayaks, and including a rudder blade (1) attached permanently to the hull (11) of the vessel and equipped with a thinned zone (9) to allow the main part of the rudder blade to turn, as well as with at least one flexible zone (17) to create flexibility in at least part of the rudder construction in a collision. The rudder construction is manufactured essentially entirely from an elastomeric material. The flexible zone (17) is formed from a weakening in the material thickness of the rudder construction and permits at least part of the rudder blade (1) to bend to the side.

Abstract: This present utility patent concerns a system of coupling keel for surfboards, which is comprised by keel 1 and lodging 2 with vertical crack 3, retention layer 4, branches 5, lower ended by a closing layer 6 and higher opening 7, by which each tongue-like part 8 of the keel 1 penetrates, and fastening screw 9 of the keel 1, whose contact edge will be lodged in the screw thread 10 of each tongue-like part. Each lodging is provided with saw-edged internal surface 11, in the vertical crack 3, and each keel 1, with tongue-like parts 8, with external face 12 corresponding to the same saw-edged surface, which couple to preserve the original arrangement designed by the manufacturer, and lodgings with external grooves 13, which reduces the possibility of pulling.

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 water floatation board includes a pair of curved side fins for an increase in holding power of the board when in the matter, and without increasing drag during board use. Each curved side fin has a concave surface that faces a centerline of the board, and a convex surface that is opposite of the concave surface. The inner and outer surfaces merge to form leading and trailing edges, and a fin tip. The use of the concave surface allows the fin area to increase without an increase in fin depth, thus providing greater holding power without increasing drag.

Abstract: A surfboard includes board, a fin connector securely mounted in the board and a fin attached to the fin connector. The surfboard has two setscrews screwed into the fin connector to hold the fin in place and a bolt extending through the fin connector, which screws into the fin to strengthen the connection between the fin connector and the fin.

Abstract: A fin plug assembly to receive and engage a fin includes a cavity, a cam with gears, and a worm gear. The fin plug assembly allows a quick and easy fore-aft adjustment of the fin. Disclosed also is a method of installing the fin plug assembly in a surfboard using a one-piece complete control jig system including the step of providing additional structural strength by removing and/or spiking the foam material in the body of the surfboard.

Abstract: Surfboard having an essentially elongate, flat basic body which is capable of floating and, during use, rests with its underside on the water, and on whose upper side there is provided a standing surface for the feet of the sports person using the board, and in which at least one fin is attached to the underside. An opening extending from the underside towards the upper side is provided in the basic body for receiving the said fin, whose extent in the transverse direction of the board, that is to say transversely to the direction of travel and transversely to the surface plane of the fin, is less than the cross-section of the fin; the outer edges of the fin cross-section at the connection point to the board are preferably designed in such a way that the outer edges rest essentially completely against the underside of the board.