Patent ID: 6918805
Filing Date: 2005-07-19
Classification: A63B

Abstract:
1. A method for improving the performance of a swim fin, comprising: (a) providing a foot attachment member having a toe portion; (b) providing a blade member connected to said foot attachment member and forming a forward extension of said foot attachment member, said blade member having opposing surfaces, outer side edges, a root portion adjacent said toe portion of said foot attachment member and a free end portion spaced from said root portion and said foot attachment member, said blade member having predetermined length between said root portion and said free end portion, said blade member having a longitudinal midpoint between said root portion and said free end portion, said blade member having a first half portion between said root portion and said longitudinal midpoint and a second half portion between said longitudinal midpoint and said free end portion; (c) providing said blade member with sufficient root portion flexibility adjacent said root portion to permit a root pivotal node to form during use within said blade member adjacent said root portion, said root portion flexibility being arranged to permit said first half of said blade member to experience a first half deflection of at least 10 degrees during a relatively light kicking stroke such as used to reach a relatively relaxed cruising speed. (d) providing said blade member with sufficient midpoint flexibility adjacent to said longitudinal midpoint to permit a midpoint bending node to form during an inversion portion of said relatively light kicking stroke within said blade member adjacent longitudinal midpoint, said midpoint bending node forming a second half deflection adjacent to said second half of said blade member during said inversion portion of said relatively light kicking stroke, said first half deflection and said second half deflection forming an S-shaped wave along said predetermined length of said swim fin during said inversion portion.