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 molded 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 foot attachment member and a free end portion spaced from said root portion and said foot attachment member, said blade member having a longitudinal dimension between said root portion of said blade member and said free end portion of said blade member, said blade member having an overall transverse dimension existing between said outer side edges, said longitudinal dimension being larger than said overall transverse dimension, said swim fin having sufficient flexibility to flex around a transverse axis to a significantly reduced lengthwise angle of attack during use, said free end portion having a recess sufficient to divide said free end portion into two tip portions, said recess defining inner edges of said blade member, at least one portion of said inner edges having an inner edge vertical dimension;
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• (c) providing two elongated rib members secured to said blade member adjacent to said outer side edges, at least one portion of said rib members having at least one rib member vertical dimension that is larger than said at least one inner edge vertical dimension.

A swim fin, comprising:

• (a) a foot attachment member, at least one soft portion of said foot attachment member being made with a relatively soft thermoplastic material;
• (b) a blade region made with a relatively stiffer thermoplastic material that is relatively stiffer than said soft portion of said foot attachment member;
• (c) at least one substantially elongated stiffening member secured to said blade region, said substantially elongated stiffening member being laterally spaced from at least one side edge region of said blade region that may twist;
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• (d) at least one flexible portion made with a flexible thermoplastic material is connected to said blade region with a chemical bond created during a phase of an injection molding process.

A method for providing a swim fin, comprising:

• (a) providing a foot attachment member;
• (b) providing a blade having opposing surfaces, outer side edges, a center longitudinal axis, and a free end portion spaced from said foot attachment member;
• (c) providing two elongated stiffening members connected to said blade adjacent to said outer side edges;
• and
• (d) arranging said center longitudinal axis of said blade to permit the formation of a recess that may extend from said free end portion toward said foot attachment member and can terminate at a desired distance from said foot attachment member for creating inner edges of said blade having a significantly lengthwise alignment and an inner edge portion having a predetermined thickness, and at least one portion of said stiffening members having a vertical dimension that is larger than said predetermined thickness.

A method for providing a swim fin, comprising:

• (a) providing a foot attachment member having a flexible portion made with a relatively flexible thermoplastic material that is formed during a predetermined step of an injection molding process, said foot attachment member having a toe portion;
• (b) providing a blade region in front of said foot attachment member, said blade region having side edges, opposing surfaces, a root portion adjacent said foot attachment member and a free end portion spaced from said originating portion and said foot attachment member, said blade region having a relatively harder portion being made with a relatively harder thermoplastic material than said relatively flexible material of said soft portion of said foot attachment member;
• (c) connecting a relatively softer thermoplastic element to said blade region with chemical bond created during said predetermined step of said injection molding process, said softer thermoplastic element being made with a relatively softer thermoplastic material that is relatively softer than said relatively harder thermoplastic material of said harder portion, at least one portion of said flexible thermoplastic element being located significantly forward of said toe portion;
• (d) providing at least one elongated stiffening member connected to said blade region with a chemical bond;
• (e) providing a region of reduced material disposed in said swim fin at a location adjacent to said toe region of said foot attachment member, said region of reduced material having sufficient flexibility to permit both said blade region and said at least one elongated stiffening member to experience significant pivotal motion around a transverse axis located adjacent to said toe region from a neutral position at rest to a reduced lengthwise angle of attack during use, said reduced lengthwise angle of attack being sufficient to increase the amount of water pushed in the opposite direction of intended swimming;
• (f) connecting a resilient thermoplastic element made with a resilient thermoplastic material to said region of reduced material with a chemical bond created during said predetermined step of said injection molding process;
• and
• (g) providing said swim fin with sufficient spring-like tension to permit both said blade region and said at least one elongated stiffening member to snap back from said reduced lengthwise angle of attack toward said neutral position at the end of a kicking stroke.

A method for providing a swim fin, comprising:

• (a) providing a foot attachment member having a flexible portion made with a relatively flexible thermoplastic material that is formed during a predetermined step of an injection molding process, said foot attachment member having a toe portion;
• (b) providing a blade region in front of said foot attachment member, said blade region having side edges, opposing surfaces, an originating portion adjacent said foot attachment member and a free end portion spaced from said originating portion and said foot attachment member, said blade region having a longitudinal midpoint located midway between said originating portion and said free end portion, said blade region having a one quarter position located midway between said originating portion and said longitudinal midpoint, said blade region having a relatively harder portion being made with a relatively harder thermoplastic material than said relatively flexible material of said flexible portion of said foot attachment member;
• (c) connecting a resilient thermoplastic element to said blade region with chemical bond created during said predetermined step of said injection molding process, said resilient thermoplastic element being made with a relatively resilient thermoplastic material that is relatively softer than said relatively harder thermoplastic material of said harder portion, at least one portion of said flexible thermoplastic element being located in an area that is forward of said one quarter position;
• (d) providing at least one elongated stiffening member connected to said blade region with a chemical bond;
• (e) providing a region of increased flexibility disposed in said swim fin at a location adjacent to said toe region of said foot attachment member, said region of increased flexibility being sufficiently flexible to permit both said blade region and said at least one elongated stiffening member to experience significant pivotal motion around a transverse axis located adjacent to said toe region from a neutral position to a reduced lengthwise angle of attack, said reduced lengthwise angle of attack being sufficient to significantly reduce the kicking effort of said swim fin during use;
• (f) providing said swim fin with sufficient spring-like tension to permit both said blade region and said at least one elongated stiffening member to snap back from said reduced lengthwise angle of attack toward a neutral position at the end of a kicking stroke;
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• (g) providing at least one opening disposed in said blade region, at least one portion of said at least one opening being located forward of said one quarter blade position.

A method for providing a swim fin, comprising:

• (a) providing a foot attachment member having a flexible portion made with a relatively flexible thermoplastic material that is formed during a phase of an injection molding process, said foot attachment member having a toe portion;
• (b) providing a blade region in front of said foot attachment member, said blade region having 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 region having a relatively harder portion being made with a relatively harder thermoplastic material than said relatively flexible material of said soft portion of said foot attachment member, said blade region having a longitudinal center axis;
• (c) providing at least one longitudinal rib member connected to said blade region with a chemical bond;
• (d) providing said at least one longitudinal rib member and said blade region with sufficient flexibility adjacent to said toe portion to permit both said blade region and said at least one longitudinal rib member to flex around a transverse axis located adjacent to said toe portion from a neutral position to a significantly reduced lengthwise angle of attack during use, said significantly reduced lengthwise angle of attack being sufficient to permit said swim fin to produce significantly low levels of kicking resistance during use;
• (e) providing said harder portion of said blade region with at least one opening located adjacent to said longitudinal center axis, said at least one opening defining inner edges of said harder portion;
• (f) providing a relatively soft thermoplastic element disposed within said at least one opening to fill the gap created by said at least one opening, said relatively soft thermoplastic element being connected to said inner edges of said harder portion with chemical bond created during said injection molding process;
• and
• (g) providing said swim fin with sufficient spring-like tension to permit both said blade region and said at least one longitudinal rib member to snap back from said reduced lengthwise angle of attack toward said neutral position at the end of a kicking stroke.

A method for providing a swim fin, comprising:

• (a) providing a foot attachment member, said foot attachment member having a flexible portion made with a relatively flexible thermoplastic material;
• (b) providing a blade region forming a forward extension of said foot attachment member, said blade region having opposing surfaces, outer side edges, 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 region having a longitudinal midpoint between said root portion and said free end portion, said blade region having a first half portion between said root portion and said longitudinal midpoint, said blade region having a harder portion made with a relatively harder thermoplastic material that is relatively harder than said relatively flexible thermoplastic material of said flexible portion of said foot attachment member;
• (c) providing at least one elongated rib member connected to said blade region with a chemical bond created during an injection molding process;
• (d) providing said first half portion of said blade region with sufficient flexibility to permit both said blade region and said at least one elongated rib member along said first half portion of said blade region to flex around a transverse axis located adjacent said root portion to a significantly reduced lengthwise angle of attack during use;
• (e) providing said free end portion with a recess sufficient to form two tip portions;
• and
• (f) connecting a relatively soft thermoplastic element to said recess with a chemical bond created during said injection molding process.