Abstract:
A braided rope, and in particular to a braided rope used in water sports that blends various fibers to create a low stretch economical rope.

Description:
RELATED APPLICATIONS 
       [0001]    The present application claims priority to and incorporates by reference thereto, United States Provisional Patent Application No. 61/670,826 filed on Jul. 12, 2012. 
     
    
     BACKGROUND 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates to a braided rope, and in particular to a braided rope used in water sports that blends various fibers to create a more economical low stretch rope. 
         [0004]    2. Background of the Invention 
         [0005]    Water sports such as water skiing and wakeboarding are extremely popular. Many products have been developed to serve these markets, including ropes. Water skiing ropes are generally comprised of fibers of polyethylene, or similar material such as polypropylene, and are woven or extruded into several strands that are then braided together to make a rope. Although there are many variations, typically the construction has a hollow center to reduce weight, and the material is one with a relatively low specific gravity so that the rope will float when in the water. Also, it is preferable to use a material that absorbs as little water as possible, like polyethylene and the like. 
         [0006]    A common characteristic of water ski ropes is that they are made from relatively flexible low modulus slightly elastic fibers. This provides the skier with the flexibility they need when changing speeds and making turns, particularly when slalom waterskiing on a course. The stretch in the rope also helps to absorb shock when the skier crosses the boat wake, and when the skier is initially pulled from the water. The most common material for this type of rope is polyethylene which will typically stretch between two and three percent of its length. Such materials also have the advantage of being relatively inexpensive. 
         [0007]    Wakeboarding is another popular water sport, and while wakeboarding ropes share many of the same characteristics of water skiing ropes—they differ in some respects. Unlike water-skiers, wake boarders need a rope with minimum or no stretch to perform tricks. This is especially true for the more skilled wake boarders. While low cost wake board ropes are commonly made from polyethylene and exhibit similar performance characteristics as water skiing ropes, high performance upper end wake board ropes are generally made out of no/limited stretch materials (such as those sold under the tradenames SPECTRA® or DYNEEMA®), these ropes are very strong and stretch less than half a percent under load. Like waterskiing ropes, the ropes come in a variety of forms, such as those shown in  FIG. 1 . 
         [0008]    One drawback of this kind of rope is that the fibers necessary to produce the response characteristics desired are expensive. These kind of fibers are about  6  times more expensive than the polyethylene fibers used in most economical water skiing ropes. In addition, based on the difference in response characteristics it is clear that the fibers used for water skiing ropes are not compatible for wake boarding ropes, and vice versa. 
         [0009]    Accordingly, a need exists for an improved more economical rope, and in particular one that is suited for use in water sports, and most particularly wake boarding. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0010]      FIG. 1  shows several prior art wakeboard ropes. 
           [0011]      FIG. 2  shows a blended rope of the present invention. 
           [0012]      FIG. 3  shows a graph of load response of the rope of the present invention. 
           [0013]      FIG. 4  shows a graph of the load response of low modulus polyethylene fiber rope. 
           [0014]      FIG. 5  shows a graph of the load response of a high modulus DYNEMA® rope. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0015]    The present invention comprises an improved rope and one that is particularly suited for water sports, and most particularly wake boarding. The rope is comprised of a blend of fibers, as shown in  FIG. 2 . The fibers include relatively low modulus relatively stretchable fibers of the type commonly used with water skiing ropes (darker colored fibers in  FIG. 2 ), and high modulus low stretch fibers commonly used for wake boarding (lighter fibers in  FIG. 2 ). 
         [0016]    Each of the differing types of fiber is woven or extruded into a plurality of strands, each strand preferable being comprised of a homogenous group of fibers. Multiple strands of each type of fiber are then woven together into a single rope that has the properties of a high modulus low stretch wake board rope. The fibers used for the low modulus strands can be comprised of polyethylene, propylene, nylon, polyester, and the like. The fibers used for the high modulus strands can be comprised of similar materials, but most preferably are comprised of no stretch or low stretch materials, such as those sold under the tradenames SPECTRA® or DYNEEMA®. 
         [0017]    The ratio of low to high modulus strands is believed to vary between about 1:3 to about 3:1, preferably from about 1:2 to about 2:1, and most preferably 1:1. This produces a rope that is similar in characteristics to prior art wake board ropes, which exclusively rely on high modulus fibers, in terms of stiffness, stretch, and strength (as shown in  FIG. 3 , which shows load on a rope of the present invention until the breaking point). 
         [0018]    As compared to the performance characteristics of a polyethylene rope and a DYNEMA® rope, as shown in  FIGS. 4 and 5  (respectively), the rope of the present invention clearly more closely matches in performance the DYNEMA® rope. In particular,  FIG. 4  shows the response of a polyethylene rope as the rope is loaded to the breaking point. The response is linear, which demonstrates that the rope will stretch relatively easily under normal use loads, which are at the lower end of the load profile.  FIG. 5  shows the response of a DYNEMA® rope. The response is not linear but exponential, which demonstrates that the rope does not stretch, or stretches very little, in the normal use range. 
         [0019]    The profile of the rope of the present invention shown in  FIG. 3  matches that of the DYNEMA® rope, and not that of the polyethylene rope. While the overall breaking point of the rope of the present invention is somewhat less than that of the rope shown in  FIG. 5 , this is considered less important than the stretch profile since the ropes described herein are never normally operated at loads near the breaking point. 
         [0020]    The rope is preferably braided using strands of the two fibers as described herein above. The actual construction of the rope can and will vary, but most preferably it would comprise 16 strands woven using any conventional weave, and preferably a 2 over 1 weave, and the like. The rope can be hollow in the center or include a center core as shown in  FIG. 1 , or in provided in any of the other arrangements as described in  FIG. 1 . 
         [0021]    The rope of the present invention has a number of advantages over the prior art. Surprisingly combining the different fibers produces a rope that performs in all regard like high performance wake board ropes of the prior art. The rope, however, is substantially less expensive to produce since it is comprised in substantial portion of lower cost fibers. 
         [0022]    While the preferred embodiment of the invention has been described in reference to the Figures, the invention is not so limited. Also, the article, method, and apparatus of the present invention are not necessarily limited to any particular application or sport. 
         [0023]    Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar to or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods, and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety to the extent allowed by applicable law and regulations. In case of conflict, the present specification, including definitions, will control. 
         [0024]    The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore desired that the present embodiment be considered in all respects as illustrative and not restrictive, reference being made to the appended claims rather than to the foregoing description to indicate the scope of the invention. Those of ordinary skill in the art that have the disclosure before them will be able to make modifications and variations therein without departing from the scope of the invention.