Swim Devices

Abstract

A swim device comprising elongated foot pockets which surround each of the feet of the swimmer, continued distally with tapers ending in neckings connected in a functional manner to blades for each foot. The neckings of the tapers of both feet may be connected to one blade (monofin). A swim device comprising a cowling of generally elongated shape which surrounds both feet of the swimmer, continued distally with a taper, ending in a necking to which one blade (monofin) is connected in a functional manner. The tapers and the hydrodynamic cross-sections of the foot pockets and of the cowling, result in stronger thrust and lower drag than in the designs of prior art.

What is claimed is: 
     
         1 . A swim device worn on the feet of a swimmer, for producing thrust by a flapping motion of the feet, comprising:
 (a) a foot pocket of elongated shape and hydrodynamic cross-section, surrounding each foot of the swimmer,   (b) a taper of the distal end section of said foot pocket, extending distally beyond the sole of the feet of the swimmer and ending as a necking of substantially smaller width than the maximum width, of said foot pocket, normal to the plane of the flapping movement,   (c) a blade of predetermined size, shape and profile, connected to said taper in a functional relationship,   
       whereby during each half-stroke of the flapping feet, water from the higher dynamic pressure area, in front and upstream of the foot pocket is made to move across the necking of the taper, into the area of lower dynamic pressure, behind the flapping blade, thereby a more efficient conversion of the power expended by the swimmer into thrust is achieved and less power is wasted as drag, than in absence of these components. 
     
     
         2 . The swim device of  claim 1 , wherein said foot pocket has transversal cross-sections of hydrodynamic shape, such as an ellipse, with the long axis parallel to the plane of the flapping movement. 
     
     
         3 . The swim device of  claim 1 , wherein a frontal cross-section of said taper in said distal end section of said foot pocket encloses an angle of less than 90 degrees, preferably between 35 and 50 degrees. 
     
     
         4 . The swim device of  claim 1 , wherein said necking of said taper has a transversal cross-section the width of which is not more than 25%, preferably not more than 15% of the largest width of the foot pocket in a direction normal to the plane of the flapping movement. 
     
     
         5 . The swim device of  claim 1 , wherein each said foot pocket on the two feet of the swimmer is connected by the respective said necking to one blade, in a functional relationship. 
     
     
         6 . A swim device, comprising:
 (a) a cowling of generally prolate shape, surrounding both feet of the user,   (b) a taper of the distal end of said cowling, extending distally beyond the soles of the swimmer and ending as a necking of substantially smaller width than the maximum width of the cowling, in a direction normal to the plane of the flapping movement,   (c) a blade of predetermined size, shape and profile, connected to said taper in a functional relationship, whereby during each half-stroke of the flapping feet, water from the area of higher dynamic pressure, in front and upstream of the cowling is made to move across the necking of the taper, into the area of lower dynamic pressure, behind the flapping blade, thereby a more efficient conversion of the power expended by the swimmer into thrust is achieved and less power is wasted as drag, than in absence of these components.   
     
     
         7 . The swim device of  claim 6 , wherein said cowling extends proximally a certain length above the ankles of said swimmer, whereby a further reduction of the drag encountered by the flapping feet is achieved. 
     
     
         8 . The swim device of  claim 6 , wherein a frontal cross-section of said taper in said distal end section of said cowling encloses an angle of less than 90 degrees, most preferably between 35-50 degrees. 
     
     
         9 . The swim fin of  claim 6 , wherein said necking of said taper of said cowling has a transversal cross-section the width of which is not more than 25%, preferably not more than 15% of the largest width of said cowling, in a direction normal to the plane of the flapping movement.