High efficiency hydrofoil and swim fin designs

A method for providing a swim fin, comprising:

• (a) providing a foot attachment member;
• (b) providing a blade member extending in front of said foot attachment member and having a longitudinal alignment, said blade member having opposing surfaces, a root portion adjacent to said foot attachment member and a free end portion spaced from said root portion and said foot attachment member, said blade member being able to experience pivotal motion around a transverse axis located adjacent said root portion to a significantly reduced angle of attack during use;
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• (c) providing a folded thermoplastic element connected to said swim fin with a chemical bond created during a phase of an injection molding process, said at least one folded element having at least one fold formed around a transverse axis that is significantly transverse to said longitudinal alignment of said blade member.

A method for providing a swim fin, comprising:

• (a) providing a foot attachment member having a toe portion;
• (b) providing a blade member extending in front of said foot attachment member and having a longitudinal alignment, said blade member having outer side edges, opposing surfaces, a root portion adjacent to said foot attachment member and a free end portion spaced from said root portion and said foot attachment member;
• (c) providing at least one elongated rib member connected to said blade member;
• (d) providing said swim fin with sufficient flexibility adjacent to said root portion to permit both said blade member and said at least one elongated rib member to flex around a transverse axis located adjacent to said root portion from a neutral position to a significantly reduced lengthwise angle of attack during use;
• (e) providing a relatively soft thermoplastic element made with a relatively soft thermoplastic material connected to said blade member with a chemical bond created during a phase of an injection molding process, said relatively soft thermoplastic element having at least one portion that is located in front of said toe portion of said foot attachment member in an area substantially between said outer side edges, said at least one portion of said relatively soft thermoplastic element is oriented at an angle to said longitudinal alignment of said blade member.

A method for providing a swim fin, comprising:

• (a) providing a foot attachment member having a soft portion made with a relatively soft thermoplastic material;
• (b) providing a blade member in front of said foot attachment member, said blade member having outer side edges, opposing surfaces, a root portion adjacent said foot attachment member and a free end portion spaced from said root portion and said foot attachment member, said blade member having a harder portion being made with a relatively harder thermoplastic material than said relatively soft thermoplastic material of said soft portion of said foot attachment member;
• (c) providing at least one relatively soft thermoplastic membrane disposed within said blade member in an area forward of said of said foot attachment member, said at least one relatively soft thermoplastic membrane being connected to said harder portion of said blade member with a chemical bond created during a phase of an injection molding process;
• (d) providing at least one elongated rib member connected to said blade member with a chemical bond;
• (e) providing said swim fin with sufficient flexibility adjacent to said root portion to permit both said blade member and said at least one elongated rib member to bend around a transverse axis located adjacent to said root portion from a neutral position to a significantly reduced lengthwise angle of attack during use, said significantly reduced lengthwise angle of attack of attack being sufficient to significantly increase the efficiency of said swim fin;
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• (f) providing said swim fin with sufficient spring-like tension to permit both said blade member and said at least one elongated rib member to snap back from said significantly reduced lengthwise angle of attack toward said neutral position at the end of a kicking stroke.