Swim Fin

Abstract

A swim fin having a rigid or flexible web pivotally mounted on a rigid frame extended forwardly from the toe of the user. The rigid web is pivoted intermediate its longitudinal ends. A flexible web is controlled with respect to longitudinal curvature. Both forms are limited in the extent of angular movement available.

Description

BACKGROUND OF THE INVENTION

This disclosure relates to swim fins used for underwater swimming and for generally improving swimming performance at the surface. It is patterned somewhat on the natural tail structure of sea mammals. Its purpose is to simulate the swimming action of such animals.

Prior swim fins have largely been comprised of molded enlarged surfaces attached to the foot and extending forwardly therefrom. These are cumbersome, both on land and in water. Because they generally continue uninterrupted throughout their full length, the turbulence of the water near the foot of the user detracts from the full water contact desired along the outer portions of the fin. Most such fins are relatively narrow, and are reduced in thickness toward their outer ends. This provides considerable flexibility in the fin and causes the fin to bend oppositely to the direction imparted to it by kicking movement, whereby forward thrust is substantially reduced.

According to the two embodiments of the present invention, relatively wide fins are mounted at a spaced distance forward from the toe of the user. They are carried by a rigid frame controlled by a foot. They are pivoted about a controlled transverse axis and the extent of pivoting movement is positively limited. Open space exists between the toe of the user and the fin, thereby positioning the fin beyond the turbulence created by the kicking action of the foot. The fin has been scientifically designed to maximize forward thrust.

SUMMARY OF THE INVENTION

The invention disclosed comprises means for attachment to the foot of a swimmer, together with a support extending longitudinally outward from the attachment means, a rigid web frame pivotally connected to the support and means for limiting the extend of angular movement of the web frame relative to the support. The web frame can be in the form of a rigid plate or hydrofoil. It also can be in the form of a flexible web whose curvature is controlled by supporting frame members.

It is one object of the invention to provide a swim fin wherein a controlled pivoting web is located outwardly from the foot of the user for maximum thrust generation.

Another object of the invention is to provide a relatively simple fin which can be readily used by any swimmer.

Another object of the invention is to provide, in a flexible fin construction, increased forward thrust by positive control of the longitudinal curvature of the web.

These and further objects will be evident from the following disclosure, taken together with the accompanying drawings, which illustrate two preferred forms of the invention. It is to be understood that these forms are only presented by way of illustration, and that they are not intended to limit the scope of the invention set forth herein.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a first embodiment of the swim fin;

FIG. 2 is a side elevation view of the swim fin in its normal attitude, the opposite angular limit of the fin movement being shown in dashed lines;

FIG. 3 is an end view taken from the right in FIG. 1;

FIG. 4 is a top view of a second embodiment of the swim fin;

FIG. 5 is a side elevation view of the swim fin in FIG. 4 in its normal operating attitude, the opposite angular limit of movement of the fin being shown in dashed lines;

FIG. 6 is an end view of the swim fin as seen from the right in FIG. 4;

FIG. 7 is a schematic view illustrating the forces generated by the swim fin illustrated in FIGS. 1-3; and

FIG. 8 is a similar schematic drawing relating the swim fin shown in FIGS. 4-6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1- 3 show a first form of the swim fin, including a rigid web or hydrofoil 10. The hydrofoil 10 is constructed in the form of a rigid plate, or web frame either made of solid material to provide an integral stiffening frame or having a skeletal interior frame covered by top and bottom skins of solid material. The hydrofoil 10 is symmetrical in elevation (FIG. 3) and tapers to a relatively thin leading edge at 11 and a similarly thin trailing edge at 12. As illustrated, the leading edge 11 and trailing edge 12 are each V-shaped, the included angle at the center of leading edge 11 being smaller than that at trailing edge 12. The side edges of hydrofoil 10 are defined by upright blades 13 which protrude beyond both the upper and lower surfaces of the hydrofoil 10. A center upright blade 19 protrudes forwardly of the hydrofoil 10. The blades 13 act as channeling guides for water contacted by the hydrofoil during its up and down movement in use.

The hydrofoil 10 is mounted to the foot of a user by means of a shoe 14 or other similar arrangement, such as straps or a foot-receiving socket. A plate 15, preferably made of rigid or semi-rigid material, extends along the bottom of the shoe 14 and forms part of a support including transversely spaced arms 16 that protrude forwardly from the toe of shoe 14 in an angular direction substantially parallel to the leg of the user while swimming with the device. At their outer ends, the arms 16 are pivotally connected to the hydrofoil 10 about a transverse axis extending through the hydrofoil plate and indicated at 17 (FIG. 2). The position of the pivotal axis is preferably intermediate the ends of the hydrofoil 10, but is not to be so limited as to location.

The angular position of hydrofoil 10 is limited by a tension member in the form of a band 18 of rubber or other suitable material. The band 18 is connected between the plate 15 and the leading edge of hydrofoil 10 at a location forward of pivot 17. The band 18 permits limited pivotal movement of hydrofoil 10 about the pivot axis at 17. It limits the angular extent of such movement as shown in FIG. 2.

In this embodiment, the hydrofoil 10 is rigid and the leading and trailing edges 11, 12 are relatively thin to reduce water friction. The illustrated angles of the leading and trailing edges of hydrofoil 10 are similar in configuration to those of the tail structure of whales, dolphins and porpoises. Hydrofoil 10 is of greater transverse dimension than its length so as to reduce the induced angle of attack during use in the water. The width of hydrofoil 10 is perpendicular to its intended forward motion through the water in operational use.

The support apparatus illustrated in the drawings locates the leading edge 11 of hydrofoil 10 forward of the toe of the shoe 14. This permits hydrofoil 10 to operate with its leading edge 11 in water not disturbed by the turbulence created by the foot and shoe 14 and insures that proper contact of the hydrofoil surfaces by water is not blocked by either the foot and shoe 14 or by the relatively open support presented by arms 16.

A second embodiment of the swim fin is shown in FIGS. 4-6. In this embodiment, the hydrofoil 20 comprises a web 21 of flexible material, such as rubber sheeting of either constant or varied thickness. The web 21 is mounted across a rigid web frame including a forward transverse frame element 22 and a transverse frame element 23 spaced slightly rearward of web 21. Web 21 is anchored across transverse element 22. Transversely spaced across web 21 and fixed to the respective transverse elements 22, 23 are a plurality of longitudinal guides 24 each presenting open concave upper and lower surfaces 25, 26 facing one another and in the flexible path of movement of the web 21. The surfaces 25, 26 serve to define the longitudinal configuration of web 21 in response to its up and down movement during swimming use, whereby the web is alternately maintained in the longitudinal concave configurations directed toward its direction of movement in the water. whereby the web is alternately maintained in the longitudinal concave configurations directed toward its direction of movement in the water.

The transverse frame element 22 is pivotally connected to the outer ends of support arms 27, which correspond to the previously described arms 16 of the first embodiment. Arms 27 are mounted to the foot of the user in substantially the same manner as previously described. A band 29 is connected between the foot of the user and a crank arm 28 fixed to the transverse member 22 at its center. Band 29 serves to limit angular movement of the web frame comprised of transverse members 22, 23 and guides 24 (FIG. 5).

In the embodiment shown in FIGS. 4-6, the operative camber line of the hydrofoil 20 will be curved away from the high pressure side of the hydrofoil in a manner similar to the configuration of a sail on a boat. The curvature of web 21 will be controlled by the surfaces 25, 26 along guides 24 and will be just opposite to the normal curvature of web 21 if not so restricted.

FIGS. 7 and 8 illustrate the general nature of the forces exerted on hydrofoils 10 and 20 respectively. The resultant vectors are indicated by arrows L, which indicate lift and B, which indicate forward propelling force. The point of rotation indicated at C is located at the hips of the user, since the proper utilization of the swim fin does not require pivoting of the swimmers knees or ankles. The illustrated direction of movement in these figures is from top to bottom or clockwise. It is to be noted that both embodiments result in a positive forward thrust during the entire length of the stroke. This also is true during the return stroke.

In the case of the first embodiment, the leading edge of the hydrofoil is free to rotate into the direction of motion, where the water encountered by the leading edge is relatively undisturbed. The leading edge of the fin is not fixed relative to the foot as in most prior swim flippers. Furthermore, in both embodiments, water is not prevented from being engaged by the leading edges of the hydrofoils by channeling members on the foot which extend to the flipper or by water channeling blades that converge into the foot on the sides of the flipper or by the foot itself, as is the case with most prior art flippers.

Claims

Having thus described my invention, I claim:

1. In a swim fin:

first means for attachment to the foot of a swimmer;

a support secured to said first means and extending longitudinally outward therefrom in a forward direction relative to the toe of said first means;

a rigid web frame pivotally connected to said support about a transverse axis located thereon spaced forwardly from the toe of said first means;

said rigid web frame comprising an integral rigid plate having a transverse width in excess of its length and presenting oppositely facing solid smooth surfaces for water contact, said transverse axis being located through the plate at a location intermediate the ends thereof;

and means operatively connected between the support and web frame for limiting the extent of angular movement of said web frame relative to said support about said axis.

2. A swim fin as set out in claim 1 wherein said support comprises:

a pair of transversely spaced arms having their respective ends fixed to the first means and pivotally connected to said plate at said axis.

3. In swim fin:

first means for attachment to a foot;

a fin-like member in the form of a web having a controllable configuration during use;

rigid frame means fixed to said first means for supporting said fin-like member, said frame means including a pivotal connection to said fin-like member about a transverse axis located across the fin-like member;

and means operatively connected between said frame means and said fin-like member for limiting pivotal movement of said fin-like member relative to said frame means about said axis.

4. In a swim fin:

first means for attachment to a foot;

a rigid frame fixed to said first means and extending forwardly to the toe thereof along a path substantially parallel to the leg of a swimmer when using the fin;

a web in the form of a transverse sheet of flexible material;

web frame means pivotally mounted to said rigid frame about a transverse axis forward of said first means for forming the web in a longitudinal concave configuration in response to kicking motion of the foot and directed toward its direction of movement in the water;

and means operatively connected between the web frame means and said rigid frame for limiting angular motion of said web frame relative to said rigid frame about said axis.

5. A swim fin as set out in claim 3 wherein said fin-like member comprises:

a transverse frame element pivotally connected to said rigid frame means at said axis;

a plurality of transversely spaced guides fixed to and extending forwardly from said transverse frame element, each guide having longitudinally convex upper and lower surfaces facing one another and respectively aligned across said transverse frame element;

said web being flexible and secured across the rear ends of said guides between the upper and lower surfaces thereof.

6. A swim fin as set out in claim 5 wherein said rigid frame means comprises a pair of transversely spaced arms having their respective ends fixed to said first means and pivotally connected to said transverse frame element at said axis.

7. In a swim fin:

first means for attachment to the foot of a swimmer;

a rigid support secured to said first means and extending longitudinally outward therefrom in a forward direction relative to the toe of said first means;

a rigid web frame pivotally connected to said support by a free pivotal connection between the web frame and said support about a transverse axis located on the support at a position spaced forwardly from said first means;

and means operatively connected between the support and web frame for permitting free pivotal movement of the web frame relative to the support about said transverse axis, while limiting the maximum amount of such movement to each side of said support.

8. A swim fin as set out in claim 7 wherein said rigid web frame comprises:

an integral rigid plate having a transverse width in excess of its length and presenting oppositely facing solid smooth surfaces for water contact.

9. A swim fin as set out in claim 7 wherein said rigid web frame comprises:

an integral rigid plate having a transverse width in excess of its length and presenting oppositely facing solid smooth surfaces for water contact;

and perpendicular rigid guide fins at the respective transverse sides of said plate extending outwardly beyond the surfaces thereof.

10. A swim fin as set out in claim 7 wherein said rigid web frame comprises:

a transverse frame element pivotally connected to said support at said axis;

a plurality of transversely spaced guides fixed to and extending forwardly from said transverse frame element, each guide having longitudinally convex upper and lower surfaces facing one another and respectively aligned across said transverse frame element;

a flexible web secured across the rear ends of said guides between the upper and lower surfaces thereof.

11. A swim fin as set out in claim 7 wherein said rigid web frame comprises:

a transverse frame element pivotally connected to said support at said axis;

a plurality of transversely spaced guides fixed to and extending forwardly from said transverse frame elements, each guide having longitudinally convex upper and lower surfaces facing one another and respectively aligned across said transverse frame element;

a flexible web secured across the rear ends of said guides between the upper and lower surfaces thereof;

said support comprising a pair of transversely spaced arms having their respective ends fixed to the first means and pivotally connected to said transverse frame at said axis.

12. A swim fin as set out in claim 7, wherein said rigid web frame comprises:

an integral rigid plate presenting oppositely facing solid smooth surfaces for water contact;

said axis being located through the plate at a location intermediate the ends thereof;

said last-named means comprising a tension member connected between said support and the end of said plate closest to said first means.

13. A swim fin as set out in claim 7 wherein said rigid web frame comprises:

a rigid plate having oppositely facing solid smooth surfaces for water contact;

said axis being located through the plate at a location intermediate the ends thereof;

said support comprising a pair of transversely spaced arms having their respective ends fixed to the first means and pivotally connected to said plate at said axis.