Abstract: The present invention provides a swim fin with a foot pocket adapted to receive a specific foot of a user and having its end conforming substantially to the alignment of the toes of the user, a blade extending from the foot pocket to a free end and having an inner edge which faces the inner edge of the other swim fin and an outer edge, the free end of the blade substantially in line with and extending inwardly from the big toe side of the foot pocket extending further than the remaining free end of the blade.

Abstract: Open-shoe type swimming flipper, to be worn on a foot wearing a boot, the shoe including an element of insole and an element for holding the front of the boot. The element of insole of the flipper is provided with a number of coupling elements which fit into a number of complementary coupling elements made in the sole of said boot. The element for holding the front of the foot is connected permanently at least along one side edge to one side edge of the part of the insole of the flipper, whilst the other side edge may be connected by clasping devices directly to the opposite side edge of the part of insole of the flipper or to the free edge of an element, which, in turn is connected to said opposite side edge of the part of insole of the flipper.

Abstract: Amphibious shoes which may be used as walking shoes with easy convertibility to swim fins. The amphibious shoes of the present invention comprise a shoe-like structure and a one-piece continuous sole-fin structure affixed to the shoe-like structure. The one-piece continuous sole-fin structure comprises a fin-like extension integrally fused to a sole portion of the shoe-like structure and a flexible folding zone, thereby facilitating the easy movement of the fin-like extension for engaging with the shoe-like structure. The fin-like extension folds upward and is secured to the shoe-like structure in the walking mode and unfolds with minimal manipulation for swimming without the need for mechanical pivoting or locking devices. The fin-like extension has a length not exceeding the distance to the user's ankle when secured in the walking mode thereby allowing for unencumbered walking but still providing ample surface area for increased propulsion during swimming.

Abstract: A swim fin that has the streamlined design of an aquatic fish or mammal with the foot pocket and flexible shaft forming a proportional and similar shape to the body of a fish. The fin is a wing-like shape separate but connected to the shaft similar to the caudal fin of a fish. This streamlined design provides an efficient form of propulsion using only power strokes and the principles of lift similar to fish. Also the tips of the stiff caudal fin create vortices to reduce drag. The flexible shaft is made of a material with a physical "memory" so that it springs back to its original manufactured shape after it flexes to produce a secondary "kick" for the swimmer. This overall "fish or whale" shape also allows for the possibility of a modular construction, if desired, where the flexible caudal shaft and stiff caudal fin can be exchanged with ones of alternative size, shape, material and design so that the fin can be adapted to each swimmer's body type, muscle type, swimming style, and aquatic conditions.

Abstract: A pair of swim fins, each fin comprising a blade having a first planar surface and defined by an elongated front edge terminated by inner and outer corners and a rear portion, the front edge and rear portion held in spaced-apart arrangement by a pair of opposed side edges extending therebetween; the rear portion of the blade having formed therein the bottom portion of a foot pocket arranged about a second planar surface for partial insertion therein of the foot of the wearer and including an open heel portion and heel strap to retain foot in the pocket; wherein the bottom portion of the foot pocket is specifically outlined for each foot, including one slightly longer side thereof bordering the inside of the foot and another slightly shorter side, spaced-apart therefrom, bordering the outside of the foot; and, wherein the second planar surface of the pocket is inclined to the outside of the first planar surface of the blade to compensate for the natural pronation of the foot in the fin when the fins are used i

Abstract: A swim fin includes a blade having a web for providing a propulsion thrust in a water environment and an opposing plate having a shoe rotatably attached. The shoe is rotatable about an axis of rotation perpendicular to the blade for a rotation of the shoe from a swimming position, wherein the web extends radially outward from the toe, to a walking position, wherein the web extends radially outward from the heel. The toe of the shoe interlocks within a transverse extending flange of the web while in the swimming position. The toe includes a tongue extending radially outward for engaging the flange in a tongue in groove interlocking manner when in the swimming position. Further, a tab extends from the toe and into a notch for indexing the shoe in the swimming position. A shaft extends outward from the sole of the shoe and through the blade where it is secured to a washer for securing the shoe to the blade.

Abstract: A flipper structure including a web portion and a shoe portion. There is an opening between the web and the shoe so that the two portions are connected at only two points on their sides. The flipper structure allows a wearer to swing the web portion during swimming or diving by manipulating an area of his foot near his ankle instead of using only his toes. This allows the wearer to swim or dive for a prolonged time and to avoid possible cramps and injury.

Abstract: A swim fin having open instep and heel portions. The swimmer's foot is retained in the fin by means of an instep strap configured to pass over the instep of the foot and a heel strap that surrounds the heel of the foot. The instep strap passes through a pair of longitudinal slots in the planar foot portion of the fin and up and over the foot such that the ends of the instep strap are secured at the instep. Preferably, to facilitate adjustments, the ends of the instep strap overlap one another and are secured with hook and loop fasteners. A locking strap overlays the instep strap at the instep of the foot and further secures the fin to the foot. The instep strap conforms to the instep of the foot and lends itself to enclasping the arch of the swimmer's foot. Preferably, the heel strap is integrally formed from the instep strap and the ends of which overlap one another are secured with hook and loop fasteners. A heel locking strap overlays the heel strap at the ankle and further secures the fin to the foot.

Abstract: A swim fin which automatically locks into a rigid configuration when pressure is exerted against the blade during the propulsion stroke, transferring the forces and stresses past the foot to the ankle area and lower leg of the wearer, the fin having a pair of rigid brace members extending from the rear of the blade portion, with the free ends of the brace members connected to an ankle harness by a rod and slot combination and with the brace members pivotally connected to a rigid fulcrum positioned at or near the front of the foot. The slots in the brace members are offset approximately 20 to 25 degrees from the longitudinal axis of the brace members. When little or no pressure is applied to the blade, the brace members and blade can move relative to the ankle harness, but when pressure is applied to the blade, such as during the propulsion stroke, the brace members pivot on the fulcrum, automatically locking the free ends of the brace members to the ankle harness.

Abstract: An expandable swim flipper includes a blade having at least an expandable portion thereof. The expandable portion radially expands in response to water resistance directed to a first surface of the blade. The surface area of the flipper is correspondingly increased to propel a swimmer at a faster rate through the water. The expandable portion radially contracts in response to water resistance directed to a second surface of the blade. The surface area of the flipper is correspondingly reduced, and is thereby subject to decreased water resistance. In a first preferred embodiment of the invention, the flipper blade is formed of expandable lateral members joined to a central member having a constant width. In a second, equally preferred embodiment, the flipper blade is formed of lateral members having a constant width and joined to an expandable central member. In a third, equally preferred embodiment of the invention, the flipper blade is expandable over its entire width.

Abstract: A swimming aid which includes a main body having a support section by which the swimming aid is carried by the user and a fin section which extends away from the support section and includes a distal free edge portion and spaced apart side edge portions extending between the distal free edge portion and the support section, and at least one elongated substantially resilient element extending from the support section towards the distal free edge portion of the fin.

Abstract: A combination water shoe and swim fin is provided offering foot protection on land or in water. A pliable sole having a slip resistant lower surface is formed to a shoe upper body formed of mesh material allowing for quick water drainage from the inner foot receiving cavity formed between the sole and upper body. Extending from the sole outward from the outer shoe sidewall is a swim fin. The swim fin extends laterally outward, and does not extend forward beyond the toe fence of the shoe.

Abstract: A swimming flipper device that is worn on the foot of a person while swimming in the water. The flipper device has an exterior surface that is viewable from points surrounding the flipper. At least one source of light is coupled to the exterior surface of the flipper, wherein each source of light is viewable from the points surrounding the flipper. The sources of light can be light emitting diodes, chemical-luminescent devices or optical fibers coupled to a central illumination source.

Abstract: Fin according to the invention, with a seat (4, 22, 43) into which the foot may be introduced and wherein the walls (5, 8, 25, 41) of the seat grasp the foot at least partially, leaving out at least one area of the heel and of the ankle. The action of taking off and wearing the fin is made easier by providing that the fin (1, 21, 42), after the introduction of the foot into the seat (4, 22, 43) is automatically held back on the foot and removably connected thereto. There is also provided a combination of a fin of the aforesaid type with a type of footwear, like a boot (2), a shoe, or similar. In this case, the easier wear is due to the fact that the fin (1, 21, 42) is automatically held back on the footwear, being removably connected thereto.

Abstract: Methods are disclosed for increasing lift and decreasing drag on hydrofoils and swim fins. These methods include providing a hydrofoil with a highly swept back leading edge portion and orienting the hydrofoil at a significantly reduced angle of attack in which the reduced angle of attack occurs at an angle that is substantially transverse to the hydrofoil's direction of movement through a surrounding fluid medium. The lee surfaces of the hydrofoil are provided with a substantially unobstructed flow path as well as a separation reducing contour so as to permit lift generating attached flow conditions to form along such lee surfaces. Substantially rigid structural reinforcement is provided to prevent the hydrofoil from deforming significantly during use. Methods are disclosed for providing a hydrofoil with a substantially longitudinal recess or venting system located substantially along the center axis of the hydrofoil.

Abstract: Swimming flipper comprising a fin blade made of rigid material and a shoe made of soft material similar to rubber, said fin blade and said shoe being interconnected by mechanical means of joining and locking, and an insole element which can be inserted inside the shoe itself. Said locking means extend from said insole to said fin blade or vice versa, through the part of the sole of the shoe interposed between said insole and the fin blade portion underneath.

Abstract: A practice molded rubbery swim fin has a foot retaining section with a heel and toe portion and a tapered blade section extending outward from the toe portion a distance of two to five inches. A number of apertures perforate the blade to reduce hydrodynamic resistance. Side stiffening ridges extend part way down the blade, leaving the distal end of the blade free to flex. This fin enables the swimmer to move fast enough to simulate the more vigorous kicking of racing without as much effort. The structure reduces stress on the swimmer in practice.

Abstract: A foot mounted fin for use by body surfers, divers, and swimmers in water activities of all types. The strap of the swim fin fits around the ankle while the fin blade extends out beyond the foot. There is a scoop section designed to take in water at the top of the fin near the foot. Scoop discharge ports for discharging water is at the blade tip. The scoop section also channels the water to eyelet ports formed into the fin blade, enabling it to discharge water out and over the bottom surface of the fin blade while at the same time releasing it at the blade tip. This combines the forces of the two jet streams of water. This fin works with wave turbulence and ocean currents enabling the body surfer, diver and/or swimmer to fully utilize the power potential from the ocean on his/her behalf. This fin also includes side rib extensions to increase blade width and surface area without making it too long.

Abstract: A multi-part diving fin includes a blade portion having a tip and a shoe end opposite the tip, the shoe end at least partially defining a foot pocket, and a foot plate formed as a separate piece from the blade portion and having a formation for releasably engaging the blade portion, the foot plate configured so that upon engagement with the blade portion, the foot plate provides a bottom of the foot pocket. The present fin also features a vertical adjustment of the height of the foot pocket, as well as stiffness adjustment for the blade portion of the fin.

Abstract: A swim fin is disclosed that comprises a boot portion to receive the foot of a swimmer, a web portion, and a pair of side members. Each of the side members have an upper and lower arm and an upper and lower end. The lower ends of the side members are attached to opposite sides of the web portion while the upper ends of the side members attached to a leg engaging strap. A pivot means connects the side members to the boot portion and permits the side members and the web portion to rotate about the boot portion such that when the leg engaging strap is attached to the lower leg of a swimmer the web portion is pivoted to a position approximately parallel to the swimmer's lower leg.

Abstract: Swim fin equipped with buckle to secure the heel strap to the open foot pocket swim fin, such swim fin being provided sidewise of the foot pocket with a pin provided with a head enlarged with respect to its stem, and said buckle being provided with an opening, said pin and said opening being coupled for the connection of the buckle to the swim fin; said pin is provided with a radial tooth which cooperates with an abutment element protruding from the perimeter of the buckle opening, such tooth being positioned on the pin in such a manner as to prevent the downward rotation past a certain degree of the buckle with respect to the pin.

Abstract: A uniquely configured fin (2) that has an open instep (60) and which is secured to the foot of the wearer by padded securement means (52) so as to accommodate a plurality of foot sizes and wherein the fin (2) is made in a two part single mold process. Protuberances (70) may be placed on selected drag surfaces of the fin (2) to act as vacuum breakers to reduce drag of the fin (2) as it propels a swimmer through the water.

Abstract: A flipper device (1) is comprised of a fin forming front part (2) made of a relatively rigid material and device (F) for fixing the fin (2) to the foot (3) of the user. The fin (2), in its rear region (6) is fixed under the sole (4) of a foot piece (5) made of a material which is more flexible than that of the fin; at least the front part (11) of the foot piece is covered by a coating (10) of material which is more rigid than that of the foot piece (5). The coating (10) is integral with the fin (2) and is appropriate to transmit correctly an impulse from the foot (3) to the fin (2).

Abstract: Swimmimg fin of the type having an open shoe comprising a shoe portion (201) and a blade portion (101), in which the top surface (211) of the sole of said shoe portion (201) comprises two or more longitudinal ribs (121) projecting into the interior of the shoe portion (201).

Abstract: Fin with buckle for securing the heel strap to the open-shoe type fin, in which said buckle comprises: a base piece on the side of the fin next to the socket for the foot; an intermediate lever hinged at one end in said base piece; and an end piece bearing at one end the means for connection to said strap, while its other end is hinged at a point on said intermediate lever between the end hinged to the base piece and the free end.

Abstract: The present invention relates to a swimming fin comprising a shoe (1) prolonged by a blade, the blade of which is constituted by the assembly of at least one flexible blade element (2) and at least one stiffening blade element (3) which are arranged edge to edge and are rendered integral by the overmolding of an appropriate bonding material (4) over the adjacent edges. The present invention also relates to a method of manufacturing composite fins.

Abstract: A swim fin comprised of a plurality of hydrofoil blades in which the angle of attack of the blades is automatically self-adjusting by use of negative feedback through one or more hydrodynamic control surfaces. The self-adjustment of the angles of the blades results in continuous optimization of the lift vectors throughout the swimming stroke as well as for different swimming speeds and variations in water currents. To further take advantage of the increased efficiency and power, improved hydrofoil blade designs are recommended. These consist of cambered plate profiles optimized for the range of Reynolds numbers observed in scuba diving. Means to precisely define the cambered profiles, which invert between up and downstrokes, are provided. Provision for additional enhancement of power is disclosed in embodiments which multiply the number of hydrofoil blades by stacking the serial blades in substantially parallel planes without altering the overall length or width of the swim fin.

Abstract: A swim fin having manually articulable water-channeling vanes. A swim fin attachable to a human extremity such as a foot has a front portion through which a plurality of holes are present. Circumscribing these holes are corresponding clock washers that provide intermittent stops when engaged by a complementing clock washer. Such a complementing clock washer is present in a water channeling vane that is affixed over the clock washers of the swim fin by a bolt that passes into a bore (which may be threaded) within the vane. Upon full threading of the vane upon the bolt, the complementing and opposing clock washers come into close contact with one another whereby the ridge of one clock washer fits into a corresponding furrow of the other. The vane is then temporarily locked into place with respect to the swim fin, however this temporary lock is overcome by rotational pressure generally available from a human hand.

Abstract: A tube fishing reversible footwear fin having a tongue end portion projecting beyond a user's footwear is formed by a generally rectangular planar fin pivotally attached intermediate its ends to the bottom surface of the sole of a boot binding for angular rotation in either direction relative to the sole about a vertical pivoting axis. Indexing pins depending from the sole and releasably nested by an index aperture in the fin permit a user to manually rotate the fin 180.degree. in either direction while supported by a float tube to dispose the elongated tongue end portion of the fin forwardly or rearwardly of his footwear and move forwardly or backward, as desired.

Abstract: A method for the production of a flipper for swimming by injection molding that provides for the production first, of the fin (1) with one flat bent end (1a), then the molding on it of an intermediate element (2) comprising a substantially flat part (2a) overlapping the bent end and from which develop a substantially arcuate part (2b) over it and a forked part (2c) forming two ribs (3), each of which is located both above and below the fin along its lateral edges. Finally, a shoe (5) is molded onto said intermediate element which lines the internal faces of the flat part and the arcuate part.

Abstract: An improved flipper comprising a curved body having a foot pocket to receive a foot of a person therein. A shallow blade extends from a front end of the body. A heel strap is at a back end of the body to retain a heel of the foot of the person thereto. A dorsal fin extends outwardly from the body over the foot pocket. Propulsion, direction and diversion of water past the dorsal fin, will give directional guidance and stability to the person swimming in water.

Abstract: A flipper energy source for generating electricity includes a flipper or having an opening for engaging a foot and a body portion extending therefrom. The body portion includes fluid displacing surfaces which are adapted to be moved through the fluid for creating a propelling force via the movement. Such movement causes stress to be created on the surfaces of the body portion. The device further includes a piezoelectric element for converting the stress into electric power. The electric power thus generated is conditioned for use in powering electrical device(s), such as, for example, lighting, communications devices, battery rechargers, photography equipment and sonar transducers.

Abstract: A swim fin (1) for divers or swimmers, having a freely leading profile (7) as the fin blade, which always has a positive angle of attack on both the upwardly (II) and the downwardly (I) oriented stroke of the fin with respect to the oncoming flow direction of the water, which is a product of the forward motion and the stroke of the fin, wherein to increase the propulsive action with simultaneously great freedom of motion of the diver or swimmer, the profile (7) is disposed downstream, in the swimming direction, of the foot (11) of the diver or swimmer and is always located in the undertow of the foot of the swimmer, whether the stroke of the fin is oriented upward (II) or downward (I).

Abstract: A swim fin has a footwear made of flexible material to make walking easier and a support which is made of rigid material to provide rigidity. A fin is pivotally coupled to the support so that it can rotate between a locked swim position and a walk position. The support can either be permanently attached to the footwear, or removably coupled to a fitting which is permanently attached to the footwear. Extension devices can be provided so that the swim position can be unlocked from the user's knee, without the user having to bend. The shape of the fin is designed to eliminate overlapping with the other fin when the user is walking.

Abstract: Swimming flipper of the type in which the flipper part has at least two or more channels for restricting and directing the streams of fluid generated during swimming, characterized in that said channels are made with opposite concavities.

Abstract: Swimming flipper formed by a blade and a shoe, wherein the blade comprises a body of an ethylene vinyl acetate-based polymer made by injection moulding and at least partially covered by at least one flexible and elastic film of polyethylene additioned with ethylene vinyl acetate, having a decorative and/or protective and/or mechanical function. The film is applied onto and permanently connected by chemical-thermal adhesion to the body of the blade, directly during the moulding operation thereof, being previously inserted within the mould as an insert.

Abstract: A monofin comprising a swim blade having two adjustable foot pockets for attachment to the feet of a swimmer. The foot pockets can be positioned on the blade to conform with the optimal foot positions for a particular user. The blade itself has a central v-shape, so that when the foot pockets are attached to the blade each pocket leans inwardly towards the other. The blade has upturned outer wing sections to reduce the resistance during the retracting kicking motion. The blade is pitched to channel the flow of water rearwardly and centrally, focussing the water to a point behind the swimmer.

Abstract: A scuba fin has the fin section separated from the foot pocket, and connected thereto by a shaft. The shaft has substantial height, but is of minimal thickness, so that it presents little frontal area to the water. This arrangement enables the scuba fin to pass through water with reduced resistance when swimming. Also, area and mass of the fin are minimized, while still providing an appropriate area to be subjected to water for propulsion. The angle of the fin is offset from the angle of the bottom of the foot pocket, elevating the front end of the fin, so that the likelihood of tripping is substantially reduced. The novel fin reduces effort by a scuba diver, thus enabling increased bottom time, and enables more convenient and confident walking on boat decks or on terra firma.

Abstract: This invention relates to a swim fin (10) adapted to be worn on a foot of a swimmer for the purpose of varying the effect of the swimmer's leg strokes. In one preferred embodiment of the invention a sole plate (14) having a rear portion (22) of a roughly rectangular shape and front portion (18) of a roughly trapezoid shape is provided. The sole plate (14) is larger than the swimmer's foot. The sole plate may be secured to the sole swimmer's foot. In one of the preferred embodiments, this consists of a pair of flaps (34) integral with the rear portion (22) of the sole plate (14) plus adjustment straps (42) and a heel strap (46). The sole plate has a plurality of mounting holes or slots (54), which will be clear of the foot after the sole plate (14) is securely fastened to the foot. Also provided in the preferred embodiment are sets of water channeling vanes (58). The vanes (58) may be of many different designs including straight or curved in one or two dimensions.

Abstract: A foot mounted fin for use by body surfers, divers, and swimmers in water activities of all types. The strap of the swim fin fits around the ankle while the fin blade extends out beyond the foot. There is a scoop section designed to take in water at the top of the fin near the foot. Scoop discharge ports for discharging water is at the blade tip. The scoop section also channels the water to eyelet ports formed into the fin blade, enabling it to discharge water out and over the bottom surface of the fin blade while at the same time releasing it at the blade tip. This combines the forces of the two jet streams of water. This fin works with wave turbulence and ocean currents enabling the body surfer, diver and/or swimmer to fully utilize the power potential from the ocean on his/her behalf. Included in this is the swim fin mold design for efficient production of the swim fin.

Abstract: Breast-stroke swimming fine consisting of a flexible rubber shoe having a short rigid wing at the front with twisted profile and an oscillating rigid wall under one of the fin sides.

Abstract: The swim fins (10) each include a molded center guide (14) and a shoe portion (12). A first wing (16) is pivotally attached to one side of the center guide (14) by a hinge member (18). A second wing (20) is pivotally attached to the other side of the center guide (14) by a hinge member (22). The hinge members (18, 22) have a flexible web (50) and flanges (52, 54). One of the flanges (54) of the hinge (18) is inserted into a hinge bead retainer slot (24) in the center guide (14) and the other flange (52) is inserted into a hinge bead retainer slot (38) in the wing (16). One of the flanges (52) of the hinge (22) is inserted into a hinge bead retainer slot (26) in the center guide (14) and the other flange (54) is inserted into a hinge bead retainer slot (40) in the wing (20). Stop surfaces (42, 44, 46, 48) on the wings (16, 20) cooperate with stop surfaces (30, 32, 34, 36) on the center guide (14) to limit pivotal movement of the wings relative to the center guide.

Abstract: Swimming flipper (1) comprising a flexible but relatively rigid blade (3) and a relatively soft shoe (2) associated to one end of the blade. The blade (3) has an active portion (5) formed by at least two relatively rigid thermoplastic materials (5a, 5b) joined to each other and of which the second (5b) occupies a central area of the said active portion (5) in which the first material (5a) is absent. Such a central area has a width comprised between 5 and 95% of the active portion (5) of the blade (3). (FIG.

Abstract: A closed shoe swim fin which has a planar trapezoidal shaped flexible base (20) with a pair of symmetrical upwardly curved tips (26). An enlarged bulbous foot retainer (32) is integrally located on the base at the rear portion. The retainer has a rearward opening (34) and an inside cavity (36) larger than the size of the foot of a swimmer allowing flexing of the users foot. A strap (42) with a stiffening sleeve (46) and buckle (48) hold the foot into the swim fin. The base is planar in the middle and tapers toward the outside edge. The tips are flexible enough that they are responsive to a force urged against the upper surface, causing an arcuate shaped path curling away from the foot retainer creating a build-up of water pressure within the flexed surface, subsequently when the direction of travel is reversed a snapping action takes place producing a propelling force through the water.

Abstract: This invention is both preventive and corrective of a running athlete's muscle strength imbalances of the leg, hip, and back; facilitating specific rehabilitation of associated muscle injury. The sandal-like upper construction employs a special underside structure supportive of a flapper type hydro-resistance device having a special one-way drag-action. Since temperate water presents a constant given drag-factor, the user or therapist may readily readjust the extendable sole-flapper's induced hydro-drag length to suit particular therapy needs, and the capability of a given user. Additionally, the invention is constructed with special longitudinal-fin like risers, enabling user to walk upon a pool bottom without imposing scuffing damage to scuff-prone pool surfaces.

Abstract: A swim fin having a shoe and an integrally connected bi-level, relatively short fin assembly. The fin assembly includes upper and lower levels connected by side walls. Automatic valve flaps are provided at the outer portions of baffles and pivot about transverse axes. The valves automatically open and close during the kick to change the apparent area of the assembly. The bi-level arrangement increases the overall efficiency of the swim fin during use.

Abstract: Swimming flipper comprising a blade and a shoe constituted by two distinct and separable elements provided with a mutual disengageable restrained joint coupling for performing an automatic rigid step-in engagement following approach from above downwardly of the shoe relative to the blade according to a translation movement in a direction substantially perpendicular to the plane of the blade, or following a translation-rotation movement.

Abstract: Swimmer's downkick causes a swim fin to be incurved transversely thereof to generate a powerful propulsive force. The swim fin 1 comprises a foot pocket 2 and a propulsion blade 3 which is, in turn, provided at the transverse middle and between this transverse middle and respective side rails 6, 6 with a groove 15 and grooves 16, 16, respectively, wherein each of these grooves 15, 16, 16 is curved convexly from the topside toward the underside of the propulsion blade 3 and extends from a forward end of the propulsion blade 3 toward the foot pocket 2. The swim fin 1 is integrally molded from a hard type elastic material 40 and a soft type elastic material 30, wherein opposite side edges 10, 10 of the propulsion blade 3 are formed from the hard type elastic material 40 and a zone defined between these side edges 10, 10 is formed from the soft type elastic material 30.

Abstract: A swim fin for use in a swimming mode and in a walking mode has a boot portion including a shoe having a foot receiving pocket and a bulbous connecting member. Three tracks are formed in the connecting member terminating in a cavity at each end of each track, the cavity at one end being disposed substantially parallel to the axis of elongation of the foot receiving pocket and thus the foot of a swimmer and the cavity at the other end of each track being disposed approximately 90.degree. to the axis of the foot receiving pocket. The fin also includes a web having fingers adapted to be received in the cavities at one end of the tracks or in the cavities at the other end of the tracks selectively when the web is positioned in the swimming mode or the walking mode. The web also carries pins which are resiliently connected to the boot portion of the fin and positioned within a guideway in the connecting member. The configuration of the guideway is such as to urge the fingers into one or the other sets of cavities.

Abstract: A swim fin having differential stiffness characteristics is provided which includes shoe and blade portions, the shoe portion being configured to receive a swimmer's foot and the blade portion being configured to provide the desired hydrodynamic effect. The shoe portion defines a cavity which is formed in part by a differential stiffness expanse which overlies the forepart of the user's foot. The expanse includes a resilient toe region which covers the swimmer's toes and a less resilient instep region which covers the instep of the swimmer's foot. The blade portion extends from the shoe portion and is operatively connected to the instep region so as to provide the wearer with instep-directed blade portion control.