Injection molded paddle blade
A paddle blade for use in watersports is provided. The paddle blade includes: a shaft interface portion; a stiffening spine; and a blade portion including a fan-shaped tapered portion, a tip region and blade edges; wherein a hollow region is defined in the blade portion extending through the fan-shaped tapered portion toward the tip region but short of the blade edges.
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This application claims the benefit of U.S. provisional patent application No. 60/600,828 filed Aug. 10, 2004 entitled Injection Molded Paddle Blade, which is hereby incorporated by reference in its entirety for all purposes.
TECHNICAL FIELDThe present disclosure relates to a paddle blade for a self-propelled watercraft molded by a gas-assisted injection molding process.
SUMMARYA paddle blade for use in watersports is provided. The paddle blade includes: a shaft interface portion; a stiffening spine; and a blade portion including a fan-shaped tapered portion, a tip region and blade edges; wherein a hollow region is defined in the blade portion extending through the fan-shaped tapered portion toward the tip region but short of the blade edges.
BRIEF DESCRIPTION OF THE DRAWINGS
The present disclosure relates to a novel blade for a paddle for a self-propelled personal watercraft such as a kayak, and a novel paddle having at least one blade. Generally, gas assisted injection molding is used to form a paddle blade (shown at 10 in
Careful control of the temperature zones of the injection mold during the injection molding process allows the hollow region to be formed. The outer area of the mold, near a tip region 18 of blade 10, is maintained at a higher temperature than a shaft interface 20 (i.e. where the paddle shaft meets the blade) of the mold so that resin at the tip region of the mold remains at a low enough viscosity for the gas injected into the mold to form a gas bubble near the tip region of the mold. The nominal wall thickness of the paddle (i.e. the thickness between the hollow interior and the exterior) in some embodiments is approximately ⅛ inch, but may be either greater or lesser than this. Furthermore, the walls may be thinner in the tip region 18 of paddle 10 than in other regions.
Paddle blade 10 also is lighter weight than known gas assisted injection molded paddles due to the hollow tip and spine structure. For example, paddle blade 10 has a mass of approximately 300 grams, whereas another gas assisted injection molded paddle blade of a substantially similar size having a solid tip and different stiffening structure than stiffening spine 12 was found to have a mass of approximately 370 grams. Furthermore, paddle blade 10 was found to have a buoyancy of 49 grams, centered about tip region 18, whereas the other blade was found to have a buoyancy of only 11 grams, centered about its shaft interface. Therefore, paddle blade 10 offers superior buoyancy at its tip, thereby offering superior assistance in removing the paddle blade from the water at the end of a stroke.
As shown in
The fanned profile of tip region 18 has a section profile described as two opposing airfoils. These airfoils provide lift to the paddle during the paddle stroke, increasing paddle efficiency and reducing user strain. It also provides lift to the paddle as it exits the water, reducing the energy required for the user raise the blade at the end of paddle stroke. This airfoil and lift minimizes splash during entry and exit of paddle into water, reducing incidental wetness of the user. It also provides low resistance of the paddle during entry and exit modes of the paddle stroke, thereby reducing user strain.
The fact that the hollow region 16 extends through stiffening spine 12 and toward tip region 18 results in a paddle blade that is positively buoyant. Buoyancy is centered about tip region 18, which is where buoyancy has the greatest effect on paddle performance. Buoyancy provides upward momentum to the paddle as it exits the water, reducing the energy required for the user to raise the blade at the end of the paddle stroke. Buoyancy counteracts the overall weight of the paddle in use, reducing user strain.
Paddle blade 10 represents an ideal relationship of size and length of the hollow spine, and fan shaped tip, providing a continuous structure for the full length of the paddle blade for retention of form, rigidity in use, and durability. It also results in minimal material usage and overall paddle weight, matching or less than existing designs, while providing the additional maximization of positive buoyancy. Moreover, this design provides minimum cavitation of water throughout the entire stroke. Cavitation severely reduces efficiency during the paddle stroke. Cavitation may be induced in normal use by the articulation of the spine, which in this design is most severe at the shaft and blending into the relatively flat, fan shaped tip profile that has no relative articulation.
In the embodiment of
The embodiment of
Another embodiment of a gas assisted injection molded blade, is shown at 100 in
Each of the depicted embodiments are designed to be used with a paddle shaft 24 or 124 and paddle handle 26 or 126, although these have only been schematically depicted in the figures.
Variations may be made that will be obvious to those skilled in the art. Such variations are intended to be covered by the claims that follow.
Claims
1. A paddle blade for use in watersports comprising:
- a shaft interface portion;
- a stiffening spine; and
- a blade portion including a fan-shaped tapered portion, a tip region and blade edges;
- wherein a hollow region is defined in the blade portion extending through the fan-shaped tapered portion toward the tip region but short of the blade edges.
2. The paddle blade of claim 1 wherein the hollow region extends into the stiffening spine.
3. The paddle blade of claim 1 wherein the hollow region extends into the tip region.
4. The paddle blade of claim 2 wherein the hollow region extends into the tip region.
5. The paddle blade of claim 2 wherein the hollow region is symmetrical within the blade portion and stiffening spine.
6. A paddle for use in water sports comprising:
- a paddle handle;
- a paddle shaft;
- a shaft interface portion;
- a stiffening spine; and
- a blade portion including a fan-shaped tapering portion and blade edges;
- wherein a hollow region is defined in the stiffening spine and the blade portion extending through the fan-shaped tapered portion toward but short of the blade edges.
7. The paddle of claim 6 wherein the hollow region extends into close proximity of the blade edges.
8. The paddle of claim 6 wherein the hollow region extends to within three-quarters of an inch of the blade edges.
9. The paddle of claim 8 wherein the hollow region extends to within half an inch of the blade edges.
Type: Application
Filed: Aug 10, 2005
Publication Date: May 18, 2006
Applicant:
Inventor: Peter Jones (Portland, OR)
Application Number: 11/201,633
International Classification: A63B 31/10 (20060101);