Patent ID: 11944873
Assignee: NATURE'S WING FIN DESIGN, LLC
Field: Furniture, games (Other fields)
Classification: CPC A | IPC A

Claim 3:
4. A method for providing a swim fin, said method comprising:
(a) providing a foot attachment member and a blade member in front of said foot attachment member, said blade member having a longitudinal alignment relative to said foot attachment member, said blade member having opposing surfaces, blade member outer side edges and a blade member transverse dimension between said blade member outer side edges, two sideways spaced apart elongated rib members that are connected to said blade member adjacent to said blade member outer side edges, said elongated rib members each having a rib upper edge portion and a rib lower edge portion with a vertical rib dimension between said rib upper edge portion and said rib lower edge portion and a rib vertical midpoint that is midway between said rib upper edge portion and said rib lower edge portion, a rib member midpoint transverse plane of reference that extends in a transverse direction between said rib vertical midpoints of said two sideways spaced apart elongated rib members, a root portion adjacent to said foot attachment member and a free end portion spaced from said root portion and said foot attachment member, a blade member length between said root portion and said free end portion, a longitudinal midpoint between said root portion and said free end portion, a three quarter position between said root portion and said midpoint, a one quarter position between said longitudinal midpoint and said free end portion, a first half portion between said root portion and said longitudinal midpoint, a second half portion between said longitudinal midpoint and said free end portion, a three quarter portion between said three quarter position and said free end portion, and a one quarter portion that is between said one quarter position and said free end portion, said blade member having a blade member longitudinal center axis midway between said outer side edges;
(b) providing said blade member with at least one flexible membrane member made with a flexible material that is disposed in said blade member, said flexible membrane having flexible membrane outer side edge regions;
(c) providing said flexible membrane member a transversely asymmetrical cross sectional shape having a folded membrane member that has at least one transverse fold formed around a substantially longitudinal axis when said swim fin is in said motionless state of rest;
(d) providing said swim fin with a biasing force arranged to urge at least two transversely spaced apart portions along said transversely asymmetrical cross sectional shape of said at least one folded membrane member to be urged away from each other in an orthogonal direction by an orthogonally spaced resting state vertical dimension that is at least 5% of said blade member transverse dimension along a majority of said blade member length while said swim fin is in said motionless state of rest; and
(e) arranging said folded membrane member to experience expansion from a substantially folded condition existing when said swim fin is in said motionless state of rest to an orthogonally spaced expanded state channel shaped contour under said exertion of water pressure created during at least one phase of said reciprocating kicking stroke cycle while using said cruising speed kicking stroke force, said expansion being arranged to cause a significant portion of said blade member to experience a blade portion orthogonal movement relative to said rib member midpoint transverse plane of reference from a resting state blade portion position existing when said swim fin is in said motionless state of rest to an orthogonally spaced expanded state position under said exertion of water pressure that is orthogonally spaced from said resting state blade portion position by an orthogonally spaced expanded state vertical dimension that is at least 10% of said blade member transverse dimension along a majority of said blade member length under said exertion of water pressure created during said at least one phase of said reciprocating kicking stroke cycle that uses said cruising speed kicking stroke force, and said biasing force being arranged to move said at least two transversely spaced apart portions back to said orthogonally spaced resting state vertical dimension when said swim fin returns to said motionless state of rest.