Folding swim fin

Abstract

A folding swim fin which comprises a base, arms, an elastic membrane tensioned between the arms and elements for attaching the fin to the swimmer's feet. Two opposite edges ( 1 and 2 ) of the flexible membrane ( 3 ) are attached each to one elastic strip ( 5 ). The flexible membrane ( 3 ) is made of plastic material, preferably reinforced with fibres. A preferred variant of the invention is a membrane woven with durable fibres. The strip ( 5 ) is attached to a rigid beam ( 6 ) of the base, belonging to a pair of beams connected to each other by a hinge ( 7 ) placed at a distance of 0 to ⅓ of the beam ( 6 ) length from the beam end opposite to the place of the strip ( 5 ) attachment.

1 . A folding swim fin comprising a base, arms, an elastic membrane tensioned between the arms and elements for attaching the fin to the swimmer's feet, characterised in that two opposite edges ( 1  and  2 ) of the flexible membrane ( 3 ) are attached each to one elastic strip ( 5 ), wherein the strip ( 5 ) is attached to a rigid beam ( 6 ) of the base, belonging to a pair of beams connected to each other by a hinge ( 7 ) placed at a distance of 0 to ⅓ of the beam ( 6 ) length from the beam end opposite to the place of the strip ( 5 ) attachment, and the location of the base beams ( 6 ) relative to each other is determined by a blockage ( 8 ) located near the outer end of the base beams ( 6 ), and the other two edges of the membrane ( 3 ) remain free. 
     
     
         2 . The fin according to  claim 1 , characterised in that the hinge ( 7 ) is placed inside the base beam ( 6 ). 
     
     
         3 . The fin according to  claim 1 , characterised in that the hinge ( 7 ) is an articulating hinge. 
     
     
         4 . The fin according to  claim 1 , characterised in that the hinge ( 7 ) is a uniaxial hinge. 
     
     
         5 . The fin according to  claim 1 , characterised in that the blockage ( 8 ) constitutes a tension control for the membrane ( 3 ). 
     
     
         6 . The fin according to  claim 1 , characterised in that the fin is provided with a winding shaft ( 9 ) of the membrane ( 3 ) for changing the bearing surface of the fin. 
     
     
         7 . The fin according to  claim 6 , characterised in that one of the strips ( 5 ), of the pair of strips, is attached to the base beam ( 6 ) so as to ensure free rotation of the strip about its longitudinal axis and constitutes the winding shaft ( 9 ) of the membrane ( 3 ). 
     
     
         8 . The fin according to  claim 6 , characterised in that the winding shaft ( 9 ) is attached to the hinge ( 7 ). 
     
     
         9 . The fin according to  claim 1 , characterised in that a mounting rail ( 10 ) for attaching tools is attached to the beam ( 6 ). 
     
     
         10 . The fin according to  claim 9 , characterised in that the outer surface of the mounting rail ( 10 ) has a rough surface which constitutes a non-slip element when walking. 
     
     
         11 . The fin according to  claim 1 , characterised in that the flexible membrane ( 3 ) is made of plastic material, preferably reinforced with fibres. 
     
     
         12 . The fin according to  claim 11 , characterised in that the fibres reinforcing the membrane ( 3 ) are selected from the group of fibres: glass, polyamide, Kevlar, carbon fibre, aramid fibre. 
     
     
         13 . The fin according to  claim 1 , characterised in that the membrane ( 3 ) is made of woven fibres. 
     
     
         14 . The fin according to  claim 1 , characterised in that the elastic strips ( 5 ) are made of plastic material. 
     
     
         15 . The fin according to  claim 14 , characterised in that the elastic strips ( 5 ) are made of composite of fibres bonded with resin. 
     
     
         16 . The fin according to  claim 15 , characterised in that the fibres of the strip ( 5 ) are selected from the group of fibres: glass, polyamide, Kevlar, carbon fibre, aramid fibre. 
     
     
         17 . The fin according to  claim 1 , characterised in that the strips ( 5 ) have a rectangular cross-section. 
     
     
         18 . The fin according to  claim 17 , characterised in that the cross-section of the strip ( 5 ) varies along the longitudinal axis of the strip in such a way that the thickness of the strip is the largest at the place of connection of the strip ( 5 ) with the base beam ( 6 ), and the smallest at the strip end opposite to the base beam. 
     
     
         19 . The fin according to  claim 1 , characterised in that the membrane ( 3 ) has the shape of an isosceles trapezium. 
     
     
         20 . The fin according to  claim 1 , characterised in that the strips ( 5 ), of the pair of strips of one fin, have the same length. 
     
     
         21 . The fin according to  claim 1 , characterised in that the strips ( 5 ), of the pair of strips, have different lengths. 
     
     
         22 . The fin according to  claim 1 , characterised in that the strip ( 5 ) of greater length is attached to the base beam ( 6 ) via a shaft ( 11 ) with an axis of rotation parallel to the longitudinal axis of the strip ( 5 ). 
     
     
         23 . The fin according to  claim 1 , characterised in that in the mounting rail ( 10 ), toots necessary for underwater work are mounted in a manner that allows them to become disconnected by sliding. 
     
     
         24 . The fin according to  claim 1 , characterised in that, mounted in the mounting rail ( 10 ), the tool is protected against accidental sliding out by a latch blockage. 
     
     
         25 . The fin according to  claim 1 , characterised in that the blockage ( 8 ) is constituted by a bolt ( 12 ) attached articulately with its one end to one of the base beams ( 6 ), and with the other end to the other beam ( 6 ) through an ovular opening ( 13 ), and immobilised with a lock ( 14 ), preferably a nut or a knob. 
     
     
         26 . The fin according to  claim 1 , characterised in that the base beam ( 6 ) has a tubular shape of rectangular section. 
     
     
         27 . The fin according to  claim 1 , characterised in that the base beam ( 6 ) has a tubular shape of oval-like section. 
     
     
         28 . The fin according to  claim 26  or  claim 27 , characterised in that the base beam ( 6 ) is made of a plastic material selected from the group consisting of: steel, aluminium, titanium, carbon-resin composite, ABS.