The present invention relates generally to an improved kayak or canoe, and more particularly, to an improved kayak or canoe hull including a coaming having at least one support bridge.
Canoes and kayaks may include a hull that may be rotary molded from polyethylene or other suitable thermoplastic materials. Rotational molding is explained in detail in ROTATIONAL MOULDING OF PLASTICS (R. J. CRAWFORD, ed., Research Studies Press, Ltd., 2nd ed. 1996). The hull of such a kayak or canoe usually includes a cockpit in which a paddler sits. The canoe or kayak may also include a coaming at least partially bordering the cockpit and integral with the kayak or canoe's hull. The coaming adds structural support to the watercraft around the opening of the cockpit and may also provide a groove into which a skirt that encircles the paddler can be placed if needed to prevent water from entering the opening of the canoe or kayak and collecting inside the kayak or canoe's hull.
Attached to the coaming may be a brace against which a paddler places her knees, for example. Knee braces of this sort are seen in, for example, U.S. Pat. No. 6,105,531 to Knight, the entire disclosure of which is incorporated herein by reference. Knee braces allow the paddler to maneuver and control the kayak or canoe by shifting her weight to apply force to the kayak or canoe. Thus, because the knee brace is attached to the coaming, the design of the coaming has a substantial effect on the performance of the kayak or canoe.
Kayaks or canoes with larger-openings in a cockpit for multiple paddlers may have a coaming or gunwale surrounding the large opening. A canoe gunwale is the upper edge or side of the canoe. In this case stiffness in the coaming or gunwale is desired to increase overall structural integrity of the kayak or canoe, increasing the kayak or canoe's resistance to collapse. Increased resistance to collapse increases the cost-effectiveness of shipping kayaks or canoes. Thus, increased stiffness of the coaming surrounding the opening in the hull of the kayak or canoe leads-to better performance and maneuverability, and increases overall structural integrity regarding collapsibility, which reduces the product cost. In some canoes and kayaks, the seat or other device is attached to the edge of the hull, such as at the coaming or gunwale. Stresses from them can distort the hull, at least momentarily, but undesirably.
Another factor affecting the performance of a personal watercraft such as a kayak or canoe is the overall weight of the watercraft. Lower weight kayaks and canoes can obtain increased maneuverability and performance. Small increases in maneuverability and performance are critical for paddlers encountering especially treacherous waters or competing in kayak sports, for example. So while increasing the rigidity of the rim surrounding the opening in the hull of the watercraft my lead to improved performance, such an improvement in structural stiffness may be offset by an increased overall weight of the kayak or canoe if the improvement is accomplished by adding material to the coaming.
Thus, what is needed is a kayak or canoe including an improved coaming that is lighter and obtains the same stiffness as conventional cockpit coamings. A kayak or canoe with increased coaming stiffness and maintained overall weight is also needed.
The present invention is directed to an improved thermoplastic kayak or canoe comprising a thermoplastic hull having an opening, a coaming integral with the hull and at least partially bordering the opening and having outer and inner walls, the inner wall spaced apart from the outer wall, and at least one support bridge extending between the inner wall to the outer wall of the coaming.
In the preferred embodiment of the invention, the coaming includes a lip extending outwardly from the opening, providing a groove along the outer wall of the coaming for attaching a skirt to the coaming. The support bridge may contact the outer wall of the coaming.
The kayak or canoe may include a projection along the inner wall of the coamimg extending inwardly into the hull opening for attaching a knee brace to the projection and/or a plurality of holes in the projection for selectively adjusting the location of the knee brace. One or more support bridges may be adjacent the projection in the coaming.
In the preferred embodiment of the invention, the kayak or canoe hull opening provides access to a paddler's cockpit in the kayak. The canoe and/or kayak may include a hatch opening and/or an inspection port. The kayak or canoe may further include a knee brace inside the cockpit opening and/or a seat attached to the coaming, and/or a tip or bumper attached to the thermoplastic hull.
In the preferred embodiment of the invention, the kayak or canoe includes an additional support bridge in the coaming, which may be spaced from about 1 to 12 inches from the first support bridge. The inner wall of the coaming may be spaced from between about ¼ to about ¾ inches apart from the outer wall.
The present invention is also directed to an improved kayak or canoe hull comprising a hull bottom below a hull opening, and an integral coaming at least partially bordering the hull opening including an outer wall and an inner wall, the inner wall spaced apart from the outer wall, and at least one support bridge extending between the inner wall and the outer wall of the coaming.
The hull of a kayak typically includes a lip extending outwardly from the opening providing a groove along the outer wall of the coaming for attaching a skirt to the coaming. The support bridge typically contacts the outer wall of the coaming. The hull may include a projection along the inner wall of the coaming extending inwardly into the hull opening for attaching a knee brace to the projection and/or a plurality of holes in the projection for selectively adjusting the location of the knee brace. A support bridge may be adjacent the projection.
The present invention is also directed to a method of producing a thermoplastic kayak or canoe hull having a coaming including at least one support bridge comprising: providing a mold in the shape of the outer surface of the kayak or canoe hull, the mold including an inward projection for forming a support bridge in the coaming at least partially bordering an opening in the kayak or canoe hull; placing a predetermined charge of a plastic powder inside the mold; placing the mold in a heated oven; rotating the mold; cooling the mold; opening the mold; and removing the thermoplastic kayak or canoe hull including the coaming having at least one support bridge from the mold.
In the following description, like reference characters designate like or corresponding parts throughout the several views. Also in the following description, it is to be understood that such terms as “forward,” “rearward,” “left,” “right,” “upwardly,” “downwardly,” and the like are words of convenience and are not to be construed as limiting terms.
Referring now to the drawings in general and
The kayak or canoe hull may be formed by first providing a mold in the shape of the outer surface of the kayak or canoe hull. The mold must include a projection in each position that a support bridge is desired in the coaming of the kayak or canoe. Then a predetermined charge of a plastic powder is placed inside the mold and the mold is placed in a heated oven. The mold is rotated in the oven causing the plastic powder to tumble inside the mold. As the powder becomes hot, it starts to coat the inside surface of the mold. The mold is then cooled while still rotating until the plastic solidifies. The mold is then opened and the kayak or canoe hull including a support bridge in the coaming is removed from the mold. A detailed discussion of support bridges can be found in ROTATIONAL MOULDING OF PLASTICS pp. 14, 15, 132, 133, 140, 141-144,158-161 and 180-181 (R. J. CRAWFORD ed., Research Studies Press Ltd., 1992) and ROTATIONAL MOULDING OF PLASTICS 164-168 (R. J. CRAWFORD ed., Research Studies Press, Ltd., 2nd ed. 1996). Additional mold segments resulting in additional parting lines may be needed, as compared to conventional molds. Whereas the coaming of a conventional kayak can be forced past a protruding mold part, the coaming according to the preferred embodiment of this invention has such rigidity that it cannot deform, so that an additional mold segmentation is necessary.
Certain modifications and improvements will occur to those skilled in the art upon a reading of the foregoing description. By way of example, various materials other than polyethylene may be used, as will be apparent by those of ordinary skill. Other openings in a canoe or kayak can have a similar structure, if desired. It should be understood that all such modifications and improvements have been deleted herein for the sake of conciseness and readability but are properly within the scope of the following claims.
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