Abstract:
This disclosure is directed to a paddle for a watercraft having an adjustable shaft with upper and lower telescoping shaft portions. A lever in the palm grip applies tension to a cable to compress a plug at the end of the upper shaft portion to frictionally engage the lower shaft portion.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. Provisional Patent Application Ser. No. 61/400,538, filed on Jul. 29, 2010, which is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF THE PRESENT INVENTION 
     The present disclosure generally relates to paddles for use with watercraft and more specifically to paddles having an adjustable length shaft. 
     BACKGROUND OF THE INVENTION 
     Stand up Paddleboarding (SUP) is a new sport that requires the use of a very long paddle with a canoe style blade on one end and a palm grip or T Top on the other end. While traditional canoe paddles are designed for the paddler to use while sitting, SUP paddles, as the name implies, are designed for paddling while standing upright on a surfboard like craft. 
     A SUP paddler might engage in two relatively different sports while paddling: Surfing on waves or touring. The two sports are very different in how the paddlers use the paddle, and in SUP, the craft is designed to surf as well as travel over long distances of water, called touring. Because SUP users may engage in both activities in the same outing, the need to shorten the paddle for surfing and then lengthen it for touring exists. 
     In addition to the applications associated with SUP, any canoe-type paddle having an adjustable length shaft is desirable for other reasons. For example, the ability to adjust the length of the paddle allows a single paddle to accommodate users of different sizes or ages or allows the user to adjust the length for different conditions. Adjustable shaft length paddles also provide the advantage of facilitating travel by having the ability to provide a more compact form. Yet another benefit of an adjustable length paddle is the capability of adapting to different applications or uses. Accordingly, these and other reasons make adjustable length a beneficial feature of paddles used with watercraft. 
     Due to the many advantages, a number of adjustable length paddles exist, including those adapted for SUP. However, these prior art designs typically suffer from the inherent flaw that the mechanism to adjust the length protrudes or is located on the exterior of the shaft, entering into the space used by the hands. This creates a spot where the hand can no longer freely slide up and down the shaft while paddling, surfing, touring or otherwise employing the paddle with the watercraft. Furthermore, such designs also typically require holes in the shaft that weaken the structure. Other types of adjustable paddles have an internal mechanism, but the adjustment of these paddles is neither obvious to the user or requires complicated maneuvers to effect the change in length. 
     Therefore, there is a need for a watercraft paddle having an adjustable length shaft. Similarly, there is a need for such a paddle that provides adjustability while offering a smooth and unencumbered shaft to facilitate use. It would be desirable for the adjustment to be obvious to the user, and simple to operate allowing for quick adjustment while paddling. Further, there is a need for such a paddle that maintains the structural integrity of the shaft without additional holes. This invention satisfies these and other needs. 
     SUMMARY OF THE INVENTION 
     In accordance with the above needs and those that will be mentioned and will become apparent below, this disclosure is directed to a paddle for a watercraft having an adjustable shaft comprising a lower tubular shaft portion having an interior diameter, an upper shaft portion telescopically disposed within the interior diameter of the lower shaft portion, a palm grip carrying an actuator lever at a proximal end of the upper shaft portion, a cable secured to the lever and configured to transmit force to a deformable plug positioned at a distal end of the upper shaft portion, wherein tension applied to the cable by the lever compresses the plug to frictionally engage the lower shaft portion. 
     In one aspect, the upper shaft portion has a longitudinal axis and the palm grip has a transverse portion oriented substantially perpendicular to the longitudinal axis of the upper shaft portion surface, configured to engage a user&#39;s palm. Preferably, the lever pivots around an axle aligned with the transverse portion of the palm grip. Also preferably, the palm grip further comprises a recess configured to receive the lever when in a closed position. 
     In another aspect, the distal end of the upper shaft portion has a stop against which the deformable plug is configured to compress when tension is applied to the cable. Preferably, the plug and the stop have complementary surfaces configured to mate with each other and to prevent rotation of the plug and the stop with respect to each other when the plug is compressed against the stop. In one embodiment, the complementary surfaces comprise a pattern of projections and indentations. 
     In yet another aspect, the lever has a closed position that applies tension to the cable and an open position that releases tension on the cable. Preferably, the cable is attached to the lever in an over center position so that tension in the cable creates a closing force on the lever as the lever is moved adjacent the closed position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features and advantages will become apparent from the following and more particular description of the preferred embodiments of the invention, as illustrated in the accompanying drawings, and in which like referenced characters generally refer to the same parts or elements throughout the views, and in which: 
         FIG. 1  shows an elevational view, partially in section, of an adjustable shaft paddle with a closed lever, according to the invention; 
         FIG. 2  shows an elevational view, partially in section, of an adjustable shaft paddle with an open lever, according to the invention; 
         FIG. 3  shows a detail view of the palm grip of an adjustable shaft paddle, according to the invention; 
         FIG. 4  shows a side, cross-sectional view of the palm grip and upper shaft portion of an adjustable shaft paddle, according to the invention; and 
         FIG. 5  shows a detail view of the plug and stop of an adjustable shaft paddle, according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     At the outset, it is to be understood that this disclosure is not limited to particularly exemplified materials, architectures, routines, methods or structures as such may, of course, vary. Thus, although a number of such options, similar or equivalent to those described herein, can be used in the practice of embodiments of this disclosure, the preferred materials and methods are described herein. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one having ordinary skill in the art to which the disclosure pertains. Finally, as used in this specification and the appended claims, the singular forms “a, “an” and “the” include plural referents unless the content clearly dictates otherwise. 
     The invention describes a SUP or canoe paddle with an adjustable length mechanism that leaves exterior of the shaft without any protrusions, collets, holes, or buttons. The control for the mechanism is built into the paddle palm grip. The palm grip is the ending of the shaft that is designed to interact with the palm and allow for the added control of gripping the top end of the shaft so that the hand is positioned horizontal, or 90 degrees, to the axis of the shaft. The top is not round, and is preferably aligned with the blade. This gives the user a smooth, uninterrupted shaft surface and the ability to adjust length easily. 
     Furthermore, as described in detail below, the invention includes a direct mechanical tension element that is very lightweight and has minimal moving parts to corrode in the salty marine environment, and works well when wet or with sand on the moving parts. 
     As shown in  FIGS. 1 and 2 , adjustable paddle  2  includes a lower tubular shaft element  4 , which terminates in a conventional blade (not shown). Any suitable blade design can be used. Upper tubular shaft element  6  fits telescopically within lower portion  4 , preferably with adequately tight tolerance to avoid undue deflection between the two portions when they are in a telescoping relationship. Actuator lever  10  pivots on axle  11 , which is preferably oriented parallel with palm grip  12 . A first end of cable  14  is attached to axle  11  and the second end is attached to deformable plug  16  at the end of the extendable shaft element  6 . Tension on cable  14  pulls plug  16  against stop  18 , which is fixed to upper shaft  6  in any suitable manner. 
     When lever  10  is closed, as shown in  FIG. 1 , it lays flush with exterior of palm grip  12 . Cable  14  is attached to an outer radius of axle  11 , such that the closed position of lever  10  places cable  14  under tension. Cable  14  runs through plug  16 , washer  20  and terminates at cable end  22 . Cable end  22  stops cable  14  at washer  20 , which in turn distributes force applied to cable  14  to plug  16 . Preferably, cable end  22  is threaded to provide a mechanism for fine tuning the tension imparted to cable  14  when lever  10  is in the closed position. Accordingly, tension on cable  14  moves washer proximally toward palm grip  12 . Since stop  18  at the end of shaft  6  prevents motion of plug  16 , the plug is compressed axially which generates a radial expansion force. The expansion force of compressed plug  16  creates the necessary friction against lower shaft  4  to fix upper shaft  6  at a desired position. 
     Correspondingly, opening lever  10  as shown in  FIG. 2 , releases tension from cable  14 . Plug  16  then is allowed to return to its nominal dimensions, greatly reducing or eliminating the friction due to plug  16  with lower shaft  4 . Thus, upper shaft element  6  can telescope freely within lower shaft element  4  to provide easy adjustment of the overall length.  FIG. 3  is a detail view of palm grip  12 . 
       FIG. 4  shows an alternate, cross-sectional side view of palm grip  12  and upper shaft  6 . As can be seen, cable  14  is secured to lever  10  via pivot  24 . Axle  11  of lever  10  rests in a cradle  26  formed by the body of grip  12 . Thus, when lever  10  is moved to a closed position, pivot  24  is rotated to apply tension to cable  14 . Preferably, pivot  24  is positioned in an over center location, so that tension on the cable will tend to pull the lever into a closed position once pivot  24  travels beyond the apex of axle  11 .  FIG. 3  also shows recess  26  formed in palm grip  12 , which is configured to receive lever  10  when in a closed position to provide a smooth surface for the user&#39;s palm. 
       FIG. 5  shows detail views of plug  16  and stop  18 . Preferably, the mating faces of plug  16  and stop  18  have complementary features configured to prevent rotation with respect to each other. As shown, stop  18  features a plurality of projections  28 . Corresponding indentations  30  on plug  16  are configured to receive the projections. Thus, particularly when under tension, plug  16  mates with stop  18  to prevent undesirable rotation of upper shaft  6  with respect to plug  16 . As will be appreciated, this configuration helps prevent rotation of upper shaft  6  with respect to lower shaft  4 , ensuring that the user has positive control over the orientation of the paddle blade with palm grip  12 . 
     As will be recognized by one of skill in the art, several materials are suitable for construction of the various elements of the paddle. For example, in a preferred embodiment, palm grip  12  and lever  10  are formed from injection molded plastic, upper shaft  6  and lower shaft  4  are formed from a carbon composite material, deformable plug  16  is formed from rubber, polyurethane, or other similarly compliant material, and cable  14 , washer  20  and cable end  22  is formed from stainless steel or other corrosion resistant material. These materials are representative only, and can be substituted as desired. 
     Described herein are presently preferred embodiments. However, one skilled in the art that pertains to the present invention will understand that the principles of this disclosure can be extended easily with appropriate modifications to other applications.