WO2003039682A1

WO2003039682A1 - Arm fin

Info

Publication number: WO2003039682A1
Application number: PCT/IT2002/000220
Authority: WO
Inventors: Paolo Lentini
Original assignee: Boats & Watergames S.R.L. (B & W S.R.L.)
Priority date: 2001-11-05
Filing date: 2002-04-08
Publication date: 2003-05-15
Also published as: ITBS20010085A1

Abstract

The present invention comprises an arm fin, designed for the improvement and enhancement of the swim perfornance. The fin id hold by the swimmer hand and secured to the forearm through a band. The handgrip may be temporarly left free in order to perform simple operations in the water or outside, being the fin secured to the arm all the time. The ergonomic shape makes the fin similar to an offshoot of the human body itself, like a wing or the ventral fin of aquatic animals such as penguins, marine turtles, sea-lions, cetaceans, thus allowing the optimal exploitation of the arm, shoulder, breast and back muscles, as in the case of animal swimming. The principal advantage of this invention being the improved performance aspect in the human swim styles, which gain in naturalness and fluidity.

Description

Title: ARM FIN

DESCRIPTION

TECHNICAL FIELD

The present invention relates generally to swim gear, and more particularly to those swim gear of advanced design and conception that will allow a better performance.

BACKGROUND ART

With the advancement of scuba diving, snorkelling, aquagym and agonistic swimming, swim gear has likewise developed with the aim of improving, enhancing, modifying the human performance in the water. As in the case of the fins of fish or aquatic mammals, the different articles of swim gear introduced for the human use have special dynamic features that result in different types of propulsion in the water.

The analogy with fish fins and specially with aquatic mammal fins, being the man himself a mammal, is particularly important. The reference is made to their evolution, that gave the species with fins having better configuration, geometry, structure an advantage resulting in survival, and to their efficiency related to the habitat and to the features of each particular animal: the weight, the dimensions, the kind of prey, the depth of the water, ... have influenced the development of a kind of fin particularly suited to the propulsion ideal to each animal.

Besides the specific configuration and structure of the fins, the animals possess the ability to directly influence the movement of the fins with their muscles, being the fins an offshoot of the main body itself. By imitating the configuration of the animal fins, and the animal style of swimming, the man may improve his own propulsion both in terms of efficiency, performance, fluency and naturalness. At the present day, the swim gear that has been developed for human use imitates the caudal fins (those that provide the rear propulsion), in the versions for the single foot or for the two feet united (monofins) and the palmipeds with the introduction of hand paddles and special gloves that create a webbed hand. However, the imitation of the ventral fins of aquatic animals such as penguins, marine turtles, sea-lions, cetaceans by an artificial fin that is secured to the hand and to the forearm, so that it resembles more an offshoot of the body itself, would enhance the performance in the traditional swim styles and would also make new swim styles possible, that resemble more the movement of the aquatic animals, and specially the mammals, that, even not being fish themselves, have made the water their own element.

If we examine the way the arms move in the traditional human swim styles, we note that in all of them there are two main phases: one active phase (that causes propulsion) and one negative phase (that slows the speed); these phases may be simultaneous (in the dolphin style, butterfly style and breast-stroke) or alternated (in the freestyle and backstroke). The negative phase results to be extremely braking in the breast-stroke, because it is performed in the water, while in other styles it is performed in the air. The reason is that, being this element less dense than the water, it causes less resistance and the swimmer gains a faster speed.

A new swim style with no negative phase at all would greatly improve the performance. Also in the development of the naval propulsion the use of the paddle wheel (characterized by an active immersed phase, one negative phase above water-level and by a movement of the paddles on an axis that is parallel to the translational motion of the vessel) has been replaced by the use of the screw propeller, characterized by the absence of the negative phase and by a movement of the blades that is perpendicular to that of the vessel.

It is also undoubted that the human hand ability is much greater than that of the feet; for this reason, while with the traditional foot fins a faster speed may be gained only by increasing the number of kickings, by exploiting the manual ability a faster speed may also be gained by adjusting the angle of incidence of the paddle. From the study of the naval rudder it is known that the maximal efficiency is gained with angles of incidence of about 45°. This data is valid with no flow. The more the flow becomes faster, the translation speed of the paddle adds vectorially to that of the flow. In order to gain the maximum speed, it is necessary to adjust the incidence of the paddle to the new resultant; that means that the more the speed increases, the more the inclination must be increased (principle of the variable screw pitch of the propeller).

This expedient is difficult to apply with the traditional foot fins because both the fins and the monofins are not balanced, that is to say the whole surface of the blade stretches from the fulcrum downwards, and this generates such an effort that makes in turn the control of the blades difficult. A swim gear that comprises a blade whose surface is balanced, that is to say it stretches in part from the fulcrum downwards and in part in front of it, and that is controlled by the upper limbs, gifted with more ability, would grant a greater handiness and a better performance with equal effort.

DISCLOSURE OF INVENTION

The arm fin is an article of swim gear that is wing-shaped and specially designed for the human body, so as to imitate the aquatic animal ventral fins. As a novelty feature it is secured to the upper limbs and more specifically it is hold by the hand through an handgrip and secured to the forearm through a band. The band both secures the fin near the elbow and keep it in the best position of use (see Fig. 6). The band also allows the handgrip to be temporarily left free, in order to perform simple operations in the water or outside, such as: compensation, adjustment of the mask, checking of scuba instruments, ... (see Fig. 7). The fin may also be used without securing it to the forearm through the band.

The arm, from the hand to the elbow, constitutes the fulcrum of the blade, whose surface is balanced: it stretches in part downwards and in part in front of it (see Fig. 9). BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 - is a plan view of the arm fin. Fig. 2 - is a top profile view of the arm fin

Fig. 3 - is a rear profile view of the arm fin

Fig. 4 - is a front profile view of the arm fin

Fig. 5 - is a three-dimensional view of the arm fin.

Fig. 6 - shows how the arm fin is hold by the hand and secured to the arm. Fig. 7 - shows how the handgrip may be temporarily left free.

Fig. 8 - shows how the arm fins may be used in a new swim style, which produces a propelling thrust in both phases (both by "opening" and "closing" the forearms). V represents the direction of the arm movement and R the hydrodynamic resultant .

Fig. 9 - shows how the blade surface is balanced for a 40% on the abscissa axis and for a 60% on the ordinate axis.

BEST MODE FOR CARRYING OUT THE INNENTION

The arm fins are a versatile article of sporting gear that may be used for muscle workout (aquagym) and rehabilitation (physiotherapy), for the agonistic swimming, in the scuba diving, snorkelling and apnea, also to be coupled with the traditional foot fins. Moreover the arm fins represent the ideal instrument for the swimming of the paraplegic people who have developed the muscle strength specially in the upper limbs. Another innovative feature of the arm fins is the introduction of a new swim style, that may be called "Megaptera" style, as it imitates the movement of the ventral fins of the Humpback Whale, or "Megaptera Novaeangliae " (from the Greek: "megaptera" = big wings). Unlike all other known styles, in which case there are a positive phase (propelling) and a negative one (braking), the new style is characterized by the absence of the braking phase, or better by a double propelling phase. Both by opening the arms outwards and by closing them toward the body the fins produce a propelling thrust (see Fig 8). This is explained by the fact that in the traditional styles the arm movement is parallel to the movement axis of the body centre of gravity, while with the arm fins the arm movement is perpendicular to it. This is also the case of the modern naval propellers, in which the screw propulsion is characterized by no braking phase and a movement of the blades which is perpendicular to that of the vessel.

Another innovative feature in this arm fin relates to the angle of incidence of the blade, which can be adjusted. The hand ability will allow the swimmer find the best angle possible, starting from an angle of about 45°, and increasing the inclination as the speed increases, as it happens in naval propulsion with the variable screw pitch.

This operation is made possible by the fact that the fin is balanced: unlike traditional foot fins in which the whole blade surface lies from the fulcrum downwards, the arm fin balances the forces of the main surface that stretches from the fulcrum (which correspond to the rotational axis along the forearm) downwards with that of the surface that stretches in front of it, thus reducing the muscular effort of the forearm to keep it in the desired inclination. The arm fin is compensated for about 40% on the abscissa axis and for about 60% on the ordinate axis. Such surfaces, in relation to the distance of their centre of thrust from the axis of application, generate moments that make the fins extremely handy during the use (see Fig. 9). This feature is not found in any other existing fin. Furthermore, the bigger surface compensated on the ordinate axis (60%) reduces the effort on the band and allows the user to always maintain the correct inclination and get a positive thrust with any inclination it is kept, even in case the band should break or the user wished to avoid securing it.

Claims

115 CLAIMSWhat is claimed is:

1. Swim gear for the improvement of the swimming performance, characterized by the fact that it is hold by the hand and secured to the forearm 120

2. Swim gear as claimed in claim 1., characterized by the fact that it may be temporarly secured to the forearm only

3. Swim gear as claimed in claim 1., characterized by the fact that it may also be used without being secured to the forearm;

4. Swim gear for the improvement of the swimming performance, characterized by a 125 shape deriving from the imitation of the ventral fins of aquatic animals;

5. Swim gear as claimed in claim 4., characterized by the fact that it allows the swimmer to create movements in the water similar to those of the ventral fins of aquatic animals;

6. Swim gear for the improvement of the swimming performance, characterized by 130 an ergonomic shape, designed as an offshoot of the human arm

7. Swim gear as claimed in claim 6., characterized by the fact that the angle of incidence of the blade in the water can be actively adjusted

8. Swim gear for the improvement of the swimming performance, characterized by the fact that the blade is always balanced on the two axis.

135 9. Swim gear as claimed in claim 8., characterized by the fact that the propulsion is derived alternatively from the inner and the outer sides of the blade 10. Swim gear for the improvement of the swimming performance, characterized by the fact that its maximum propulsion thrust is gained with a movement which is perpendicular to the translation of the body.

140