WO2016094930A1

WO2016094930A1 - Swim fin

Info

Publication number: WO2016094930A1
Application number: PCT/AU2015/000735
Authority: WO
Inventors: James Ross PERRY
Original assignee: Perry James Ross
Priority date: 2014-12-14
Filing date: 2015-12-04
Publication date: 2016-06-23

Abstract

This invention relates to a swim fin having a base and a fin section. The fin includes a securing means adapted to releasably secure the base to the lower leg limb or shin of a wearer. The fin section is hingedly connected to the base for movement between an inactive position in which the fin section does not interfere with ankle joint movement of the wearer (e.g. for walking), and an active position for swimming. The swim fin includes releasable locking means for holding the fin section in the active position.

Description

Swim fin

Field of the Invention

[0001] The present invention relates to a swim fin for providing hydrodynamic thrust whilst swimming or for other water related activities.

[0002] The invention has been developed primarily as a swim fin, fin or flipper for use in scuba diving or snorkelling. The invention will be described predominantly in these contexts. It should be appreciated, however, that the invention is not limited to these particular applications, being potentially also adaptable for freediving (including spear fishing), bodysurfing, bodyboarding and the like.

Background to the Invention

[0003] The following discussion of the prior art is intended to place the invention in an appropriate technical context and enable its advantages to be more fully appreciated.

However, any references to prior art throughout this specification should not be construed as an express or implied admission that such art is widely known or common general knowledge in the relevant field.

[0004] Known swim fins are intended to be worn on the foot of a scuba diver or snorkeler to enhance the thrust provided from swimming kicking actions. Such designs typically have a foot pocket into which the foot is received. These pocket type fin designs can be generally classified as closed heel fins or open heel fins. Closed heel fins are worn in a manner much like that of a shoe. Open heel fins are provided with a heel strap that hold the fin in placed.

[0005] Closed heel or full foot fins have a relatively smaller foot pocket compared to the open heeled fins and are not adjustable. Such a restriction in foot pocket size is necessarily inconvenient as dive boots typically cannot be worn with these fins and therefore no thermal protection is provided. Furthermore, closed heel fins can be uncomfortable and cause blisters and cuts to the foot. Closed heel fins have also been known to slip off in use. Open heel fins provide a degree of adjustability but still give rise to similar disadvantages to those of closed heel fins.

[0006] Given that swim fins are intended for use in water based activities, including underwater activities such as scuba diving, the primary focus of swim fin design has been in relation to the functionality and performance for propelling the wearer through the water when swimming. In particular, swim fins are traditionally worn on the foot and effectively act as an extension of the foot. As such, they are relatively large and necessarily inhibit a person from walking when out of the water and thus present a trip hazard when walking on land or climbing over rocks.

[0007] Furthermore, traditional swim fins worn on the foot require significant muscle strength and endurance to be used effectively and throughout the duration of a swimming or diving session. In particular, a swimmer is required to employ foot and ankle motion when swimming with foot mounted fins which necessarily places significant amounts of additional stress on the foot, ankle and calf muscles, and related muscles. These additional stresses can cause early fatigue and exhaustion in the swimmer, and may give rise to related symptoms including pain and cramping, which can negatively affect the swimmer's performance and/or diminish their enjoyment in the water.

[0008] It is an object of the present invention to overcome or ameliorate one or more disadvantages of the prior art, or at least to provide a useful alternative.

Summary of the Invention

[0009] According to one aspect of the invention, there is provided a swim fin, including:

a base;

securing means adapted to releasably secure the base to a shin of a wearer; a fin section hingedly connected to the base for movement between an inactive position in which the fin section does not interfere with ankle joint movement of the wearer, and an active position for swimming; and

releasable locking means for holding the fin section in the active position.

[0010] In the context of this invention and as used herein the term "inactive position" is intended to refer to a configuration of the swim fin in which the fin section is not ideally placed for providing hydrodynamic propulsion when swimming, thereby enabling the wearer to walk freely with the swim fin secured to the leg of the wearer.

[001 1] Preferably, the base is in the form of a shin plate or shin pad. The shin plate is preferably configured so as to be generally contoured to fit to, against, or at least partially around the shin of the wearer. Preferably, the shin plate is curved or arcuate in cross-sectional profile, thereby fitting relatively snugly around the shin of the wearer (e.g. semi-circular in cross-section). It will be appreciated that the shin plate is typically positioned, in use, on the front of the shin of the lower leg limb of the wearer.

[0012] In some embodiments, the shin plate comprises a solid or unperforated base plate. In other forms, the shin plate can be perforated and comprise one or more openings, thereby providing the shin plate with a predetermined degree of flexibility to assist in conforming to the shape of the shin of the wearer and/or reducing the weight of the base and thus the overall weight of the swim fin.

[0013] In certain embodiments, the shin plate includes an inner lining fixed to an operatively inner surface of the shin plate, thereby being positioned intermediate or between the shin plate and shin of the wearer in use. The inner lining is preferably fixed to the shin plate by use of an adhesive. Preferably, the inner lining is formed of a resiliently compressible material such that the lining is adapted to flexibly conform to at least a portion of the outer surface profile of the shin of the wearer.

[0014] In some embodiments, the inner lining is configured to cover the entire rear surface of the shin plate, thereby providing a continuous uninterrupted surface to abut against the shin of the wearer. In those embodiments in which the shin plate comprises one or more openings, the inner lining may be formed with one or more openings substantially corresponding to, and adapted to be generally aligned with, those openings in the shin plate. In other embodiments, the inner lining may be formed with one or more openings substantially corresponding with only selected openings in the shin plate. In yet other variations, the inner lining may have no openings to provide an uninterrupted surface for abutting the shin of the wearer, regardless of whether the shin plate has one or more openings or no openings.

[0015] It will be appreciated that the flexible and compressible characteristics of the lining advantageously improve the wearability of the swim fin and improve the comfort of the wearer by ensuring that a relatively soft, pliable surface abuts against the shin of the wearer in use. Preferably, the inner lining is formed from a polymer material such as, for example, polyurethane (PU). In certain embodiments, the material from which the inner lining is formed is a foam adapted to return to its original shape when the wearer removes the swim fin/base from their lower leg after use. In some embodiments, the material from which the inner lining is formed may not completely return to its original shape, but may retain some of the profile of the shin, thereby effectively customising its shape to the particular profile of the wearer. [0016] Preferably, the securing means includes at least one strap for holding the base on the shin of the wearer, the strap being adapted to wrap around the lower leg limb (e.g. calf and/or upper ankle region) and clip to or otherwise releasably engage a corresponding engaging formation or element on the base or strap (i.e itself). In some embodiments, the securing means has a pair of straps, including an upper strap (e.g. to wrap around and be position in relative proximity to, or adjacent to, the calf region of the wearer) and a lower strap (e.g. to wrap around and be position in relative proximity to, or adjacent to, the upper ankle region of the wearer). Preferably, the or each strap is adjustable in length to enable fitment to lower limbs of various sizes.

[0017] Preferably, each strap is flexible and its proximal end is fixed to the base such that the strap can be wrapped around the rear of the lower leg limb of the wearer and its distal end can be releasably secured to the base, thereby holding the base in a desired position on the lower leg limb. In various embodiments, the proximal end of each strap is fixed to the base by suitable fixing means such as, for example, but not limited to, mechanical fasteners including nails, pins, screws, rivets, staples and the like, adhesives, or via the manufacturing process such as moulding, welding or clamping to the base. In certain embodiments, the proximal end of the strap is permanently fixed to the base or is releasably fixable to the base. The provision of releasably fixed straps provides enhanced flexibility for removing and replacing the straps to enable use of differently sized straps to suit particular applications and/or can provide advantages in terms of reducing the size of the swim fin when not in use, for example, for storage or transport.

[0018] In certain embodiments and to enable the distal end (or distal end region) of the strap to be secured to the base, a first engaging element is provided on the base and a second engaging element is provided on, or adjacent to, the distal end of the strap, whereby the first and second engaging elements are mutually releasably engagable with each other.

[0019] In one embodiment, the first engaging means on the base includes one or more spigots or lugs extending outwardly from the base, the or each spigot having a retaining formation at its distal or outer free end. Preferably, the or each retaining formation is an enlarged formation or head at the distal end of the respective spigot. In some embodiments, the or each spigot, together with its retaining formation, is generally L-shaped, T-shaped or V- shaped, whereby the associated distal or outer free end is relatively greater in sized compared to the proximal end adjacent the base. In certain embodiments, the first engaging means includes two or more spigots. Preferably, the two or more spigots are generally L-shaped spigots arranged such that the respective retaining formations of one or more spigots extend laterally and in generally opposing directions. For example, in certain embodiments, one or more of the spigots extend generally to the left of the base, and one or more spigots extend generally to the right of the base. In one preferred embodiment, the first engaging means includes a series of three horizontally aligned, spaced apart spigots, including a first right- handed generally L-shaped spigot, a central spigot, and a first left-handed generally L-shaped spigot. In one particularly preferred embodiment, the first engaging means includes two vertically spaced apart rows of spigots, including a pair of right-handed generally L-shaped spigots, a pair of central spigots, and a pair of left-handed generally L-shaped spigots.

Preferably, the upper row of spigots is substantially aligned with the lower row of spigots. It will be appreciated that the arrangement of spigots is not limited to those described above but can be any suitable arrangement, including regular and irregular patterns. In some embodiments, the central spigot(s) has a retaining formation, whilst in other embodiments the central spigot(s) does not have a retaining formation and is provided primarily as a locating means for the strap.

[0020] In certain embodiments, the proximal end of the strap is provided with a series of receiving formations (e.g. holes), the receiving formations being arranged and configured to correspond with the arrangement of spigots of the first engaging means, whereby the spigots are receivable in or through the receiving formations to secure the proximal end of the strap to the base. Preferably, the strap is formed of a material (e.g. rubber) which enables the receiving formations to resiliently deform to enable engagement with, and optionally

disengagement from, the retaining spigots. In other forms, the spigots and/or receiving formations themselves can be resiliently deformable rather than relying on the material of the strap itself. In some embodiments, one or more supplementary receiving formations is provided to enable selective adjustable mounting of the proximal end of the strap to the base.

[0021] In some embodiments, the first engaging element can be provided on or adjacent to the proximal end of the strap (e.g. the portion of the strap fixed to the base), rather than directly on the base. In such embodiments, the strap is preferably fixed to the base by suitable means such as, for example, an adhesive or a mechanical fastener.

[0022] In one embodiment, the second engaging means on the strap includes one or more engaging formations for securing the distal end of the strap to the base, by way of releasable engagement with the first engaging means. Preferably, the second engaging means is configured to facilitate adjusting the effective length of the strap, whereby upon fastening of the second engaging means with the first engaging means the strap securely holds the base against the lower limb/shin.

[0023] In one embodiment, the second engaging means includes a series of receiving formations (e.g. holes) at the distal end region of the strap, the receiving formations being arranged and configured to correspond with the arrangement of spigots of the first engaging means, whereby the spigots are receivable in or through the receiving formations to secure the distal end of the strap to the base, thereby holding the base against the lower leg/shin of the wearer. Preferably, the strap is formed of a material (e.g. rubber) which enables the receiving formations in the distal end to resiliently deform to enable engagement and disengagement from the retaining spigots. In other forms, the spigots and/or receiving formations themselves can be resiliently deformable rather than relying on the material of the strap itself. Preferably, the series of receiving formations in the distal end of the strap include one or more auxiliary receiving formations, whereby a selected one or more of the receiving formations in the distal end of the strap can be used to engage the spigots such that the effective length of the strap is sized to correspond with the size of the lower limb of the wearer. In some embodiments and to facilitate the adjustment provided by the auxiliary receiving formations, the spacing between each formation can correspond to the spacing between the spigots (e.g. the left, central and right spigots). In other embodiments, the spacing between individual receiving formations at the distal end of the strap is less than the spacing between the spigots on the base such that several groups of formations are provided for engaging the first engaging means, thereby providing the adjustable functionality of the strap. In such embodiments, the reduced spacing between the formations at the distal end advantageously facilitates finer adjustments of the effective length of the strap in use. In such embodiments, in which the proximal and distal ends of the straps engage the spigot, the spigots are preferably of sufficient height to accommodate twice the thickness of the strap underneath the head of the spigot.

[0024] It will be appreciated that the strap is not limited to having first and second engaging elements as described above but can employ any suitable selectively releasable engaging means such as, for example, snap-lock elements, press-studs, loop and hook fasteners, ratchet mechanisms, threaded fasteners, and the like. In some embodiments, such engaging elements can optionally be used in conjunction with a quick release mechanism for disengaging the first and second engaging elements when it is desired to remove the swim fin from the lower limb after use. [0025] It will also be appreciated that, in the context of the invention described herein, the references to engagement of the distal end of the strap to the base, or engaging means at the distal end of the strap or similar, are not intended to be limited to a reference to the extreme distal end (although it may include this portion), but is to be understood as a distal end region to enable the strap to be adjustably wrapped around lower limbs of a range of sizes in a firm, snug or otherwise secure fit as required.

[0026] In other embodiments, the or each strap is provided as an individual member(s) (i.e. the distal end of the strap(s) is not fixed to the base) adapted to be wrapped around the lower limb of the wearer and the base, the strap(s) including a pair of mutually engagable engaging portions at respective opposite ends of the strap, for fastening the ends of the respective strap together, thereby securing the base to the lower limb.

[0027] Preferably, the locking means is a selectively releasable positive locking mechanism. In some embodiments, the locking means includes a first retaining element associated with the base/shin plate and a second retaining element associated with the fin section, the first and second retaining elements being mutually engagable for securely holding the fin section in the active position.

[0028] Preferably, the first retaining element extends from the distal end of the base/shin pad and includes a retaining formation for abutment with the second retaining element. In certain embodiments, the first retaining element includes a retaining formation and the second retaining element includes an abutment edge or surface engagable with the retaining formation.

[0029] In some embodiments, the retaining formation includes a hook-like element such as, for example, a barbed member, protrusion, lug, lip, ridge or other suitable formation.

Preferably, the retaining formation is biased towards an engaged position. In some

embodiments, the first retaining element includes a resiliently flexible tongue wherein the retaining formation is formed at or near the distal end of the flexible tongue. Preferably, the tongue is flexible to enable the retaining formation to move into and out of engagement with the abutment edge or surface. Preferably, the retaining formation (barb) is arranged at a predetermined location along the flexible tongue. In some embodiments, the retaining formation (barb) is spaced from the distal end of the tongue. The flexible tongue is preferably curved, more preferably convexly curved with the barbed member formed on an outer surface of the tongue. [0030] It will be appreciated by those skilled in the art that the first retaining element is not limited to the form of the exemplary flexible tongue as described herein but can include any suitable retaining formation such as, for example, a spring-loaded pin, a hinged or slidable latch or the like. It will also be appreciated that certain embodiments may incorporate pairs of retaining elements, or groups of three or more retaining elements.

[0031] Preferably, the tongue is configured such that it can be flexed, against the biasing force, upon selective application of a releasing force, thereby moving the retaining formation out of the locking position wherein the fin section can be hingedly moved (rotated) away from the active position. The tongue preferably includes a tab or other suitable formation to which the releasing force can be applied (e.g. adapted to be operated by heel, toe or foot pressure of the wearer). It will be appreciated that the ability to manipulate or operate the tab to release the tongue by way of heel, toe or foot manipulation is advantageous in that the wearer does not have to bend down to their ankle to operate the tongue with their hand. This is particularly advantageous in applications such as, for example, scuba diving where the diver has a substantial amount of other equipment in their hands and/or strapped to their body, including a heavy gas tank on their back.

[0032] Preferably, the retaining formation (e.g. barbed member) has an outer surface adapted to slide or pass over the abutment edge as the retaining formation moves into and out of the engaged/locking position. The retaining formation (e.g. barbed member) preferably has an inner surface which at least partially overlies and engages the abutment edge, thereby releasably retaining the fin section in the active position.

[0033] Preferably, the locking means holds the fin section (in the active position) in a predetermined position relative to the base/shin pad. The fin section is preferably hingedly connected for rotation through an angle of 90 degrees or more, more preferably 100 degrees or more, as the fin section rotates between the inactive and active positions. In certain embodiments, the fin section is configured for rotation through an angle within the range of 100 degrees to 170 degrees as it moves between the inactive and active positions. In one particularly preferred embodiment, the fin section is configured from rotation through an angle of approximately 130 degrees as it moves between the inactive and active positions. It has been found that rotation of the blade through these preferred ranges advantageously positions the fin section, in the active position, relative to the lower leg/shin of the wearer to promote an improved ergonomic swim kicking stroke which causes enhanced thrust force per kick in response to both upward and downward kicks. [0034] Preferably, the locking means holds the fin section (in the active position) relative to the base, whereby the included angle (a) between the respective longitudinal axes of the fin section and the base is approximately 100 degrees or more, more preferably approximately 130 degrees or more. In certain preferred embodiments, the included angle between the fin section and the base, in the inactive position, is approximately 160 degrees.

[0035] Preferably, an extension member is arranged at the distal end of the base so as to be arranged between the flexible tongue and the shin pad, thereby spacing the flexible tongue and retaining formation from the hinged connection between the base and the fin section. The extension member is preferably in the form of a plate. Preferably, the plate includes one or more reinforcing members. In some embodiments, the plate has two reinforcing members arranged in spaced apart side-by-side relation and extending generally parallel to each other, and preferably generally parallel to the longitudinal axis of the plate. Preferably, the plate extends at an angle relative to the base, thereby extending in an operatively forward direction away from the leg of the wearer.

[0036] In some embodiments, the fin section has an opening or cut-out section at its proximal end, wherein a side or end wall of or adjacent the opening defines the abutment edge of the second retaining element. Preferably, the opening or cut-out section is generally square or rectangular, thereby providing the proximal end of the fin section with a generally opened ended U-shaped profile. It will be appreciated that the opening or cut-out may be any other suitable shape, and may not be a perfect square or rectangle, but may include notches or bulges or other edge variations.

[0037] Preferably, the fin section includes a stop for limiting the extent of rotational movement of the fin section away from the inactive position. In some embodiments, the position in which the fin section abuts the stop substantially corresponds with the active position. That is, the stop effectively defines the active position and determines the included angle between the respective longitudinal axes of the base and fin section.

[0038] Preferably, the hinged connection between the base and the fin section is located at or near the distal end (i.e. an operatively lower end) of the base. In some embodiments, the proximal end of the fin section is rotatably mounted to the distal end of the base for rotation about a shaft, thereby providing the hinged connection therebetween. In other forms, a press fit or other suitable engagement between the base and the fin sections may be employed to provide the rotational movement between the inactive and active positions about a predetermined axis of rotation.

[0039] Preferably, the distal end of the base includes a pair of stub axles extending outwardly in opposite directions and the proximal end of the fin section includes a pair of holes arranged to be respectively aligned with the stub axles, wherein a respective shaft can pass through each hole to thereby provide the rotatable connection between the base and the fin section. In some embodiments, the shaft is in the form of a fastener, such as a threaded screw, for engaging a corresponding internal thread associated with the respective stub axle. In other forms, a single shaft may extend through both stub axles.

[0040] In certain embodiments, a friction reducing element is associated with each stub axle to facilitate the rotational movement between the base and fin section. In some embodiments, the friction reducing elements is in the form of a bearing (e.g. a caged ball or roller bearing).

[0041] Preferably, each stub axle has a cylindrical outer surface. In some embodiments, the proximal end of the fin section has a pair of cover members for covering the respective stub axles. Preferably, each cover member has a curved inner surface which is generally concentrically arranged about the respective stub axle.

[0042] Preferably, the fin section is arranged for rotation about an axis substantially coaxial with a longitudinal axis of the pair of stub axles. Preferably, the hinge point of the fin is located, in use, at the front of (i.e. forward of) the ankle of the wearer.

[0043] Preferably, the fin section is resiliently biased out of the active or swimming position. The positive locking mechanism preferably releasably secures the fin section in the active position against the resilient bias. The resilient bias is preferably provided by a biasing means. The biasing means may be any suitable biasing mechanism, device or arrangement such as, for example, coil springs, leaf springs, resiliently flexible tabs formed from metal, plastic or other suitable material. In some embodiments, the biasing means is in the form of a spring element. In other forms, the biasing means may be provided by the manner and/or material from which the hinged connection between the base and fin section is formed. Preferably, the swim fin includes one or more springs for providing the bias between the base and fin section. In one preferred embodiment, the resilient bias is provided by a pair of springs arranged on respective sides of the hinged connection between the shin pad and the fin section. In some embodiments, the swim fin includes a pair of torsion springs to provide the desired resilient bias, each torsion spring having a coiled section and an arm at each free end. Each arm is preferably elongate. Preferably, the arms of each springs are biased away from each other, thereby being adapted to provide opposing forces. The end portions are preferably adapted to engage the shin pad and the fin section, respectively. In some embodiments, the arms of each torsion springs are brought closer together as the fin section moves towards the active position, and the arms move away from each other as the fin section moves towards the inactive position.

[0044] Preferably, the coil of each torsion spring is positioned over a respective stub axle and a first arm of the pair of arms engages the base and a second arm of the pair of arms engages the fin section, whereby stored energy within the coil causes the arms to act on the base and the fin section respectively to lift or move the fin section out of the swimming position when the locking means (e.g. barb) is released.

[0045] Preferably, the extension plate extending from the distal end of the base includes receiving formations for at least partially receiving the first arms or free end portions of each hinge torsion spring. The receiving formations in the extension plate are preferably in the form of grooves or slots, more preferably open ended slots (e.g. open at one or both ends). In some embodiments, the shape of the groove substantially corresponds to or complements the shape of the respective arm of the torsion spring. In certain embodiments, each groove is curved or arcuate or otherwise includes a bent or angled portion. Preferably, the pair of grooves includes respective left- and right-handed grooves. It will be appreciated that the curved grooves may advantageously assist in retaining the arms of the spring within the grooves as the resilient nature of the material from the spring is formed causes the free arm to attempt to straighten within the groove thereby causing the arm to act on or engage an inner side wall of the groove.

[0046] The second arms of the springs preferably act on an operative underside of the fin section. Preferably, the proximal end of the fin section includes receiving formations, formed in its operative underside, for receiving the second arms or free end portions of each hinge torsion spring. The receiving formations in the underside of the fin section are preferably in the form of grooves or slots, more preferably open ended slots (e.g. open at one or both ends). In some embodiments, only a portion of the second arms are received in or seated within the respective grooves on the underside of the fin section. In other forms, the grooves may generally correspond to or complement the shape of the second arms of the torsion springs, wherein the associated second arm is substantially received in the corresponding groove. [0047] It will be appreciated that the resilient biasing means is not limited to

[0048] Preferably, the swim fin includes a holding device for releasably holding the fin section in the inactive position when not in use. In one embodiment, the holding device is a selectively releasable snap locking arrangement including a male portion arranged on the base/shin pad and a female portion arranged on the fin section, whereby the female portion is adapted to releasably snap fittingly receive the male portion to hold the fin section in a predetermined position relative to the base/shin pad in the inactive position. In some embodiments, the female section is arranged towards the upper end or top of the base/shin pad and the male portion is positioned so as to be spaced from the proximal end of the fin section by an amount such that the female and male portions come into alignment when the fin section is in the inactive position.

[0049] It will be appreciated that, in other forms, the male portion and female portion of the holding device can be arranged on the fin section and shin pad, respectively. The snap locking arrangement advantageously provides a simple, elegant and efficient means by which the wearer can easily secure the fin section in the inactive position against the shin pad when the wearer is not swimming, and readily release the fin section so that it can be lowered towards the swimming position, when required. In certain embodiments, the swim fin includes two or more holding devices.

[0050] In certain embodiments, the male portion includes a bulbous element and the female portion includes a generally C- or U-shaped receiving element engagable with the bulbous element, thereby releasably holding the fin section in the inactive position.

[0051] Preferably, the holding device holds the fin section (in the inactive position) relative to the base, whereby the included angle between the respective longitudinal axes (β ) of the fin section and the base is approximately 45 degrees or less, more preferably approximately 30 degrees or less. In certain preferred embodiments, the included angle between the fin section and the base, in the inactive position, is approximately 20 degrees.

[0052] Preferably, the fin section has a mounting portion at its proximal end and a blade portion extending from the mounting portion to its distal end. Preferably, the blade portion is formed from a relatively flexible material. In some embodiments, the mounting portion is formed of a relatively rigid material. Preferably, the blade portion is securely fixed to the mounting portion. In various embodiments, the blade portion may be fixed to the mounting portion by means of one or more fasteners or an adhesive.

[0053] Preferably, the blade portion includes a flexible webbing structure extending between a pair of side arms. The side arms are preferably in the form of support elements arranged to extend along respective sides of the fin section, thereby enhancing the structural rigidity of the fin section. The intention is that the support elements are not rigid elements (although, they may be) but preferably are formed to have a degree of flexibility, thereby enabling the blade portion to flex upwardly or downwardly in response to the kicking action of the wearer whilst swimming. It will be appreciated by those skilled in the art that this flexible characteristic of the blade portion advantageously assists in enhancing the thrust force generated by the swim fin and thus the forward propulsion delivered to the wearer.

[0054] In some embodiments, the blade portion is formed from plastic, polypropylene, rubber or other suitable material. In some certain embodiments, the mounting portion is formed from plastic, carbon fibre or other suitable material.

[0055] It has been found that the particular positioning and orientation of the fin section achieved by the manner in which the present swim fin is secured to the leg of the swimmer, and the relative angle between the base and fin section in the active position, advantageously promotes an improved ergonomic positioning giving rise to a more natural and efficient kicking action, whereby the swimmer uses the knee and hip joints and the larger muscle groups associated with these joints. Thus, the swim fin advantageously removes or reduces the loading force of the fin kick on the foot and ankle region, thereby reducing foot and ankle stress and the likelihood of cramping in the calf region when swimming.

[0056] In some embodiments, the blade portion includes one or more hydrodynamic elements formed on or within the webbing for enhancing the hydrodynamic performance of the fin. The hydrodynamic elements may include raised foils or depressed chutes.

[0057] According to another aspect of the invention, there is provided a swim fin, including:

a base;

a securing means adapted to releasably secure the base to a shin of a wearer; a fin section for aiding movement of the wearer through a body of water, the fin section being rotatably mounted to the base; and

locking means for holding the fin section in an active position. [0058] According to yet another aspect of the invention, there is provided a swim fin, including:

a base adapted to be releasably secured to the base to a shin of a wearer; and a fin section for aiding movement of the wearer through a body of water, the fin section being rotatably mounted to the base and selectively movable between a non-swimming position and a swimming position.

Brief Description of the Drawings

[0059] A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:-

[0060] Figure 1 is a perspective view of an embodiment of the swim fin according to the invention, attached to the lower leg of a wearer with the fin section in the inactive position;

[0061] Figure 2 is a perspective view of the swim fin of Figure 1 , with the fin section in the active position for swimming;

[0062] Figure 3 is a schematic perspective view of the swim fin, showing the relative positioning of the fin section between the active and inactive positions;

[0063] Figure 4 is a perspective view of the swim fin in the inactive position, with the straps removed;

[0064] Figures 5A-B show the swim fin in the active position and an enlarged view of the detail of the locking mechanism for holding the fin section in the active position, respectively; and

[0065] Figures 6A-C show an underside view of the swim fin, a torsion spring, and an enlarged view of the hinged connection between the base and the fin section, respectively.

Preferred Embodiment of the Invention

[0066] Referring initially to Figures 1 and 2, the invention in the illustrated embodiment provides a swim fin 1. The swim fin 1 includes a base in the form of a shin plate or pad 2 which is adapted to be releasably secured to the shin at the front of the lower leg 3 of a wearer. [0067] The shin pad 2 has a curved or arcuate cross-sectional profile so as to be generally contoured to fit relatively snugly around the shin of the wearer. As shown in Figures 1 and 2, the shin pad 2 is typically positioned on the front of the lower leg limb of the wearer. The shin pad 2 is formed as a continuous member without perforations from a plastic material and has some degree of flexibility to assist in conforming to the shape and movement of the shin of the wearer in use.

[0068] In the illustrated embodiment, the shin pad 2 has a resiliently compressible inner foam lining 4 fixed to an operatively inner surface of the shin pad 2 so as to be positioned, in use, between the shin pad 2 and shin 3 of the wearer. The inner lining 4 is preferably fixed to the shin pad 2 by use of an adhesive. The inner lining 4 is preferably formed from a polymer material such as, for example, polyurethane (PU).

[0069] It will be appreciated that the flexible and compressible characteristics of the inner lining 4 advantageously improve the wearability of the swim fin 1 , improving the comfort of the wearer by ensuring that a relatively soft, pliable surface abuts against the shin of the wearer in use.

[0070] Again referring to Figures 1 and 2, the securing means in the illustrated embodiment is in the form of a pair of flexible rubber straps, including an upper strap 5A for wrapping around the calf region of the lower leg 3 and a lower strap 5B for wrapping around the upper ankle region of the wearer. Advantageously, each strap 5 is independently adjustable in length to enable a snug or fit to the particular portion of the lower leg 3 around which the respective strap 5 is secured, thereby ensuring that the shin pad 2 and swim fin as a whole stays in the desired position on the lower leg 3 throughout the duration of the swimming activity for which the fin is used.

[0071] The shin pad 2 has a first engaging means in the form spigots 6 fixedly secured and extending outwardly from the shin pad 2. In the illustrated embodiment, the spigots 6 are arranged in a rectangular arrangement with two vertically spaced apart rows with three spigots 6 in each row. As most clearly seen in Figure 2, there are two vertically spaced apart rectangular arrangements of spigots 6 for attaching the upper and lower straps (5A, 5B), respectively.

[0072] The outermost or side spigots 6 have a retaining formation in the form of an enlarged head 7 at the outer free end. In the illustrated embodiment, the outermost spigots include a pair of right-handed generally L-shaped spigots 6A where the head 7 extends generally to the right, and a pair of left-handed generally L-shaped spigots 6C, where the head 7 extends generally to the left. The two central spigots 6B do not have a retaining formation or head 7.

[0073] As will be described in detail below, the spigots 6 serve the dual functionality of providing a mounting formation for both the proximal end 8 and the distal end 9 of the respective strap 5.

[0074] The proximal end 8 of each strap 5 is provided with a series of receiving formations in the form of holes 10 for releasably attaching the proximal end 8 of each strap 5 to the spigots 6. In the exemplary embodiment illustrated in the drawings, the proximal end 8 of each strap 5 is provided with an arrangement of six holes 10 in a rectangular formation to correspond to the arrangement of spigots 6 on the shin pad 2. The straps 5 are formed of a rubber material which enables the outermost holes 10 to resiliently deform and stretch over the head 7 of the associated spigot (6A, 6C) to enable engagement with, and disengagement from, the retaining spigots 6 as and when required.

[0075] As most clearly shown in Figure 5, the distal end 9 of each strap 5 has a second engaging means in the form of an array of holes 1 1 for releasably attaching the distal end 9 of each strap 5 to the spigots 6. Again, the rubber material from which the straps 5 are formed enables the holes 1 1 in the distal end 9 to resiliently deform to enable engagement and disengagement from the retaining spigots (6A, 6C), to secure and release the strap from the lower leg 2 when required.

[0076] It will be appreciated therefore that the distal end 9 overlies the proximal end 8 of the associated strap 5 when the shin pad 2 is secured in position on the lower leg 3. Accordingly, the height of each spigot 6 is advantageously sized to accommodate at least twice the thickness of the strap 5 underneath the associated head 7. As the central spigots 6B do not have a head 7 these spigots 6B act to facilitate in locating and maintaining alignment of the proximal and distal ends (8, 9) of the strap 5.

[0077] The array of holes 1 1 includes supplementary or surplus holes to facilitate adjusting the effective length of the strap 5 to suit the particular circumference of the leg of the wearer. More specifically, the holes 1 1 are spaced apart in a manner which enables selected groups of holes 1 1 to correspond to the arrangement of the spigots 6 such that the distal end 9 of the strap 5 to hold the shin pad 2 against the lower leg/shin 2 of the wearer. [0078] Referring to Figure 3, the swim fin 1 includes a fin section 12 hingedly connected to the lower end of the shin pad 2 for movement between an inactive position (as shown in solid lines in Figure 3), and an active position (as shown in dashed lines in Figure 3).

[0079] In the inactive position, the fin section 12 is generally upright with its distal end 13 positioned so as to be relatively higher than its proximal end 14 (and higher than the point of hinged connection with the shin pad 2) such that the fin section 12 does not interfere with ankle joint movement of the wearer. In this upright position, the fin section 12 is not ideally placed for providing hydrodynamic propulsion when swimming. Accordingly, when the swim fin 1 is strapped to the leg of a wearer and the fin section 12 is in the inactive upright position, the fin section 12 does not come into contact with the foot of the wearer such that the wearer can freely walk with the swim fin 1 secured to the leg of the wearer.

[0080] A holding device in the form of a selectively releasable snap locking device 15 for releasably holding the fin section 12 in the inactive position when not in use is provided on the swim fin 1. In the illustrated embodiment, the snap locking device 15 includes a male portion 16 arranged on an upper surface of the fin section12 and a female portion 17 arranged on the shin pad 2 adjacent to the upper arrangement of spigots 6 (or upper strap). The male portion 16 is positioned so as to be spaced from the proximal end 14 of the fin section 12 by a distance such that the female and male portions (16, 17) come into engaging alignment when the fin section 12 is in the inactive position (Figures 1 and 3).

[0081] The male portion is in the form of a protrusion or bulbous element 14 and the female portion includes a generally C-shaped receiving element 17 for receiving the bulbous portion 14 in releasable engagement to hold the fin section 12 in the inactive upright position.

[0082] The snap locking device 15 is advantageously adapted to hold the fin section 12 in a predetermined position relative to the shin pad, in the inactive position, such that the fin section 12 is angled away and spaced from the knee of the wearer to further facilitate the ease or unrestricted leg movement whilst the wearer is walking with the swim fin 1 secured to the lower leg 3.

[0083] Thus, the snap locking device 15 provides a simple, elegant and efficient means by which the wearer can use simple hand manipulation, typically in the region of the distal end 13 of the fin section 12, to move the fin section 12 into and out of engagement with the snap locking device 15 to secure the fin section 12 in the inactive position against the shin pad 2 when the wearer is not swimming, and readily release the fin section 12 so that it can be lowered towards the swimming position, when required.

[0084] The fin section 12 has a rigid mounting portion 18 at its proximal end 14 and a flexible blade portion 19 secured to and extending from the mounting portion 18 to its distal end 13. The mounting portion 18 is formed a relatively rigid plastics material and the blade portion 19 is formed from rubber or silicon. It will be appreciated that the mounting and blade portions may be formed from suitable materials other than those of the exemplary embodiment described above.

[0085] The blade portion 19 includes a flexible webbing structure 20 extending between a pair of side arms 21. The side arms 21 are preferably in the form of support elements arranged to extend along respective sides of the fin section 12. The side arms 21 are somewhat more rigid than the webbing 20 so as to enhance the overall structural integrity of the fin section 12. The intention is that the support elements have a degree of flexibility, thereby enabling the blade portion 19 to flex upwardly or downwardly in response to a kicking action of the wearer whilst swimming. It will be appreciated by those skilled in the art that this flexible characteristic of the blade portion advantageously assists in enhancing the thrust force generated by the swim fin and thus the forward propulsion delivered to the wearer.

[0086] The swim fin 1 further includes a releasable locking means in the form of a selectively releasable positive locking mechanism 22 for holding the fin section 12 in the active position. As best shown in Figures 2 and 5A, when the fin section 12 is in the active or swimming position, the fin section is essentially folded or rotated down and held in a position so as to extend over the foot of the wearer. It is in this swimming position that the wearer can use the blade for propulsion in water.

[0087] The locking mechanism 22 is provided to ensure that the fin section 12 is securely maintained in the active position in use whilst the wearer is swimming.

[0088] In the illustrated embodiment, the locking mechanism 22 includes a first retaining element extending from the distal end of the shin pad 2 and for abutment with a second retaining element on the fin section 12. The first and second retaining elements are mutually engagable for securely holding the fin section 12 in the active position (Figures 5A and 5B). [0089] As most clearly seen in Figures 4, 5A and 5B, the first retaining element includes a curved flexible tongue 23 on which a retaining formation in the form of a barbed member 24. The second retaining element includes a lip edge or an abutment edge 25 formed on the rigid mounting portion 18 of the fin section 12.

[0090] The abutment edge 25 is formed by way of a U-shaped opening 26 in the mounting portion 18 at the proximal end 14 of the fin section 12. More specifically, the abutment edge 25 is formed by a notch 27 in an end wall 28 of the opening 26.

[0091] The curve of the flexible tongue 23 and the plastic material from which it is formed biases the barbed member 24 outwardly towards an engaging position. A tab 29 is provided at the distal end of the tongue 23 to which the wearer can selectively apply a releasing force by way of heel, toe or foot pressure. This releasing force acts to flex the tongue 23, against the biasing force, to cause the barbed member 24 to move out of overlying engagement with the abutment edge 25. Once the barbed member 24 is free of the abutment edge 25, the fin section 12 can be rotated out of the active position towards the inactive position.

[0092] The barbed member 24 has an outer surface 30 adapted to slide or pass over the abutment edge as the retaining formation moves into the engaged/locking position, and an inner surface 31 which at least partially overlies and engages the abutment edge 25 in the engaged position. The inner surface 31 slides or passes over the abutment edge 25 as the barbed member 24 moves out of the engaged position.

[0093] As most clearly seen in Figure 3, an extension member in the form of a plate 31 extends from the distal end of, and at an angle relative to, the shin pad 2. The flexible tongue 23 extends from the extension plate 31. This configuration ensures that the flexible tongue 23 and barbed member 24 are spaced from shin pad 2 (i.e. forward of the hinged connection between the shin pad 2 and the fin section 12). In the illustrated embodiment, the extension plate 31 includes a pair of wedge shaped reinforcing members for stiffening the extension plate. The reinforcing members arranged in spaced apart parallel side-by-side relation. These reinforcing members provide advantages in terms of reducing flexing of the extension plate to ensure proper locking functionality is maintained during engagement and disengagement of the locking mechanism 22, and also to ensure that the engagement is maintained when swimming. [0094] The fin section 12 includes a stop for limiting the extent of rotational movement of the fin section away from the inactive position. That is, the position in which the fin section 12 abuts the stop substantially corresponds with the active position and thereby determines the included angle between the respective longitudinal axes of the base and fin section in the active position. In the illustrated embodiment, the stop is in the form of a pair of inwardly directed stop plates 32 extending inwardly from respective side mounting arms 33 of the mounting portion 18 of the fin section 12. The side mounting arms 33 are positioned such that respective side edge portions of the extension plate 31 abut against the side mounting arms 33, thereby limiting further rotational movement of the fin section 12.

[0095] It has been found that the particular positioning and orientation of the fin section 12 achieved by the manner in which the present swim fin 1 is secured to the leg 3 of the wearer, together with the relative angle between the shin pad 2 and fin section 12 in the active position, advantageously promotes a more natural and efficient kicking action. In particular, the manner of mounting the swim fin 1 on the lower leg promotes a kicking action in which the swimmer primarily uses the knee and hip joints and the larger muscle groups associated with these joints, rather than foot and ankle movement. Thus, the manner in which the swim fin 1 is mounted to the lower leg advantageously removes or reduces the loading force on the foot and ankle region, thereby reducing foot and ankle stress and the likelihood of cramping in the calf region when swimming.

[0096] The hinged connection between the shin pad 2 and the fin section 12 is located at or near the distal operatively lower end of the shin pad 2. The hinge point of the fin is located, in use, at the front of (i.e. forward of) the ankle of the wearer.

[0097] In the illustrated embodiment, the distal end of the shin pad 2 includes a pair of stub axles 34 extending outwardly in opposite directions. The side mounting arms 33 at the proximal end 14 of the fin section 12 includes a pair of mounting holes 35 arranged to be aligned with the respective stub axles 34. A respective shaft 43 passes through each mounting hole 35 to define the axis of rotation 'X' between the shin pad 2 and the fin section 12. In the illustrated embodiment, the shaft 43 is provided by the shank of a threaded fastener received through the mounting holes 35 and corresponding ores within the respective stub axles 34.

[0098] Each stub axle 34 has a cylindrical outer surface profile and is arranged underneath a cover member 36 from about the mounting holes 35 at the end of the side arms 33. Each cover member 36 has a curved inner surface which is generally concentrically arranged about the respective stub axle 34 to enable relative rotation therebetween.

[0099] Referring to Figure 6, the fin section 12 is advantageously resiliently biased out of the active or swimming position. The positive locking mechanism 22 releasably secures the fin section 12 in the active position against the resilient bias. In the illustrated embodiment, the swim fin 1 includes a pair of torsion springs 37 arranged on respective sides of the hinged connection between the shin pad 2 and the fin section 12 for providing the resilient bias between the shin pad 2 and fin section 12.

[00100] As most clearly seen in Figures 6B and 6C, each torsion spring 37 has a coiled section 38 and an elongate arm 39 at each free end. Figure 6C shows the torsion spring 37 isolated from the swim fin 1 and in a state of rest.

[00101 ] The coil 38 of each torsion spring 37 is positioned over a respective stub axle 34 such that a first arm 39 engages the extension plate 31 of the shin pad 2 and a second arm 39 engages the fin section 12. The engagement of the arms 39 between the shin pad 2 and fin section 12 is such that each spring 37 is pre-tensioned upon mounting, whereby stored energy within the coil causes the arms 37 to act on the extension plate 31 and the fin section 12 respectively to lift or move the fin section 12 out of the active swimming position when the locking means 22 is released.

[00102] By way of this mounting arrangement, the arms 39 are brought closer together as the fin section 12 moves towards the active position, and the arms 39 move away from each other as the fin section 12 moves towards the inactive position. Thus, the arms of each spring 37 are biased towards each other and adapted to provide opposing forces.

[00103] Referring to Figure 6B, the extension plate 31 includes receiving formations in the formed of curved slots 40 for receiving the first arms 37 the torsion springs 37. As the grooves 40 are curved it will be appreciated that straight elongate arms 39 must be bent to fit with the respective grooves. This mounting advantageously assists in retaining the arms 39 of the springs 37 within the grooves 40 as the resilient nature of the material from the springs 37 are formed causes the free arms to attempt to straighten within the groove thereby causing the arm to act on or engage an inner side wall of the groove. [00104] The second arms 39 of the springs 37 act on an operative underside of the fin section 12. More specifically, the operative underside of the mounting portion 18 has receiving formations in the form of grooves 41 for receiving the second arms 39 of each hinge torsion spring 37. In the illustrated embodiment, only a portion of the second arms 39 are received in or seated within the respective grooves 41 on the underside of the fin section 12.

[00105] By way of the biased hinged connection, the fin section 12 is advantageously rotatably mounted to the distal end of the shin pad 2 for selective rotation between the inactive and active positions. The spring force applied between the shin pad and the fin section is sufficient to lift the fin section out of the active position when the wearer presses on the tab 29 and releases the locking mechanism 22. The spring force is preferably not so strong as to rotate the fin section all the way into the inactive position to be held in place by the snap lock device 15 (although such an embodiment is possible). Rather, in the preferred embodiment, the spring force is adapted to simply ensure that the fin section automatically pops upwardly out of the engaged position upon activation of the releasing tab 29. Once the fin section 12 has been released from the active position, the user can then simply rotate the fin section towards the inactive position until the male portion 16 of the snap lock device 15 engages the female portion 17 by hand manipulation.

[00106] The Ergofin does not provide "increased forward thrust propulsion with each kick". What it does is take the force of the fin kick off the foot and ankle, and instead uses the lower leg/shin. This promotes a more efficient and natural swimming motion using the knee and hip joints and the larger muscle groups associated with these joints. This relieves foot and ankle stress and stops the possibility of calf cramping during swimming.

[00107] Accordingly, the present invention, at least in its preferred embodiments, provides a safe, robust, effective, easy to use and relatively inexpensive device for enhancing the comfort and usability of a swim fin. These advantages are particularly evident in those situations where the wearer of the swim fin is required to walk a distance between the location at which the swim fin is secured to the leg of the wearer and the location at which the wearer enters the water. The ability to strap the swim fin to the lower leg limb ensures that the wearer can wear other footwear at the same time as wearing the swim fin such as, for example, dive boots. In those preferred embodiments in which the fin section is biased out of the active position, together with the ability to rotate the fin section 12 between the active and inactive positions, reduces the risk of the fin section becoming a trip hazard as the spring bias can act to hold the fin section above the ground level when the wearer is walking even when the fin section is not clipped in place by the snap lock device 15. The ability to rotate the fin section provides a range of motion out of the active position through which the fin section passes or can be held in and pose no trip hazard to the wearer.

[00108] In addition, the manner in which the swim fin 1 is secured to the lower leg of the wearer removes or reduces the forces transferred to the foot and ankle region during the swim kicking action. This positioning of the swim fin promotes a more efficient and natural leg motion, whilst swimming, in which the knee and hip joints are employed, together with the larger muscle groups associated with these joints. Thus, this positioning of the swim fin advantageously relieves foot and ankle stresses and loadings and can thereby reduce the onset of fatigue and/or cramping when swimming. In these and other respects, the invention represents a practical and commercially significant improvement over the prior art.

[00109] Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms. In particular, it will be readily appreciated that although the description herein has been made with reference to the structural and functional characteristics of a single swim fin 1 , a wearer will typically wear a pair of swim fins; one on the left leg and one on the right leg of the wearer.

Claims

1 . A swim fin, including:

a base;

releasable locking means for holding the fin section in the active position.

2. A swim fin according to claim 1 , wherein the base is in the form of a shin pad, the shin pad being configured to fit at least partially around the shin of the wearer.

3. A swim fin according to claim 2, wherein the shin pad includes an inner lining fixed to an operatively inner surface of the shin plate, thereby being positioned, in use, between the shin plate and shin of the wearer.

4. A swim fin according to any one of the preceding claims, wherein the securing means includes at least one strap for holding the base on the shin of the wearer, the strap being adapted to wrap around the lower leg limb and releasably engage a corresponding engaging formation on the base.

5. A swim fin according to claim 4, wherein the securing means has a pair of straps.

6. A swim fin according to claim 4 or claim 5, wherein a proximal end of each strap is fixed to the base.

7. A swim fin according to claim 6, wherein the proximal end of the strap is releasably fixable to the base.

8. A swim fin according to any one of claims 4 to 7, wherein a first engaging element is provided on the base for fixing the proximal end of each strap to the base, and a second engaging element is provided on the strap, whereby the first and second engaging elements are mutually releasably engagable with each other to hold the distal end of each strap to the base.

9. A swim fin according to claim 8, wherein the first engaging means on the base includes one or more spigots extending outwardly from the base, each spigot having an enlarged retaining head at an outer free end.

10. A swim fin according to any one of the preceding claims, wherein the locking means includes a first retaining element associated with the base and a second retaining element associated with the fin section, the first and second retaining elements being mutually engagable for securely holding the fin section in the active position.

1 1. A swim fin according to claim 10, wherein the first retaining element extends from the distal end of the base and includes a retaining formation for abutment with the second retaining element.

12. A swim fin according to claim 10 or claim 1 1 , wherein the first retaining element includes a retaining formation in the form of a protrusion, and the second retaining element includes an abutment edge engagable with the protrusion.

13. A swim fin according to claim 12, in which the first retaining element includes a resiliently flexible tongue to enable the retaining formation to move into and out of engagement with the abutment edge, wherein the retaining formation is formed at or near the distal end of the flexible tongue.

14. A swim fin according to claim 12 or claim 13, wherein the protrusion is in the form of a barbed member which is biased towards an engaged position.

15. A swim fin according to claim 14, wherein an extension member is arranged at the distal end of the base so as to be arranged between the flexible tongue and the shin pad, thereby spacing the flexible tongue and retaining formation from the hinged connection between the base and the fin section.

16. A swim fin according to any one of claims 12 to 15, wherein the flexible tongue includes a tab adapted to be operated by foot manipulation for releasing the retaining formation from the abutment end.

17. A swim fin according to any one of claims 10 to 16, wherein the fin section has an opening at its proximal end, wherein an end wall of the opening defines the abutment edge of the second retaining element.

18. A swim fin according to claim 17, wherein the fin section includes a stop for limiting the extent of rotational movement of the fin section away from the inactive position.

19. A swim fin according to any one of the preceding claims, wherein the hinged connection between the base and the fin section is located at or near the distal end of the base.

20. A swim fin according to any one of the preceding claims, wherein the proximal end of the fin section is rotatably mounted to the distal end of the base for rotation about a shaft, thereby providing the hinged connection therebetween.

21. A swim fin according to claim 20, wherein the distal end of the base includes a pair of stub axles extending outwardly in opposite directions and the proximal end of the fin section includes a pair of holes arranged to be respectively aligned with the stub axles, wherein a respective shaft can pass through each hole to thereby provide the rotatable connection between the base and the fin section.

22. A swim fin according to claim 21 , wherein a friction reducing element is associated with each stub axle to facilitate the rotational movement between the base and fin section.

23. A swim fin according to claim 20 or claim 21 , wherein the fin section is resiliently biased out of the active position.

24. A swim fin according to claim 23, wherein the swim fin includes one or more springs for providing the bias between the base and fin section.

25. A swim fin according to claim 24, including a pair of springs arranged on respective sides of the hinged connection between the shin pad and the fin section.

26. A swim fin according to claim 24 or claim 25, wherein each spring is a torsion spring having a coiled section and an arm at each free end, the arms being adapted to respectively engage the shin pad and the fin section, wherein the arms of each torsion springs are brought closer together as the fin section moves towards the inactive position, and the arms move away from each other as the fin section moves towards the active position.

27. A swim fin according to claim 26, wherein the coil of each torsion spring is positioned over a respective stub axle and a first arm of the pair of arms engages the base and a second arm of the pair of arms engages the fin section, whereby stored energy within the coil causes the arms to act on the base and the fin section respectively to move the fin section out of the active position when the locking means is released.

28. A swim fin according to claim 27, wherein the extension plate extending from the distal end of the base includes receiving formations for at least partially receiving the first arms of each torsion spring.

29. A swim fin according to claim 27 or claim 28, wherein the proximal end of the fin section includes receiving formations for receiving the second arms of each hinge torsion spring.

30. A swim fin according to any one of the preceding claims, wherein the swim fin includes a holding device for releasably holding the fin section in the inactive position. In some embodiments, the female section is arranged towards the upper end or top of the base/shin pad and the male portion is positioned so as to be spaced from the proximal end of the fin section by an amount such that the female and male portions come into alignment when the fin section is in the inactive position.

31. A swim fin according to claim 30, wherein the holding device is a selectively releasable snap locking arrangement.

32. A swim fin according to claim 30 or claim 31 , wherein the holding device includes a male portion arranged on the base and a female portion arranged on the fin section, whereby the female portion is adapted to releasably snap fittingly receive the male portion to hold the fin section in a predetermined position relative to the base in the inactive position.

33. A swim fin according to claim 32, wherein the male portion includes a bulbous element and the female portion includes a generally U-shaped receiving element engagable with the bulbous element, thereby releasably holding the fin section in the inactive position.

34. A swim fin according to claim 32, wherein the fin section has a mounting portion at its proximal end and a blade portion extending from the mounting portion to its distal end.

35. A swim fin according to claim 34, wherein the blade portion is has a web formed from a relatively flexible material.

36. A swim fin according to claim 34 or claim 35, wherein the mounting portion is formed from a relatively rigid material.