Patent Publication Number: US-6991501-B2

Title: Paddle and method of manufacture thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims subject matter disclosed in U.S. Provisional Application No. 60/475,462 which was filed on Jul. 23, 2003 by Stephen E. Wilce. 

   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   (Not Applicable) 
   BACKGROUND OF THE INVENTION 
   This invention relates to paddles or oars for manually propelling and maneuvering small boats such as kayaks or canoes for example. More particularly the invention relates to a blade and shaft construction for such paddles and to methods for manufacturing paddles. 
   Many contemporary paddles for small watercraft are made by attaching a tubular shaft to one end of a relatively broad plastic blade. The attachment is subjected to sizable forces during use and needs to be of high strength. The common current practice is to use a molded plastic blade having an integral socket formed thereon for receiving and seating an end of the shaft. The socket adds weight to the paddle, increases inertial resistance to movement of the paddle and increases the cost of manufacture of the blade. 
   Small differences in weight can be of considerable significance during the use of paddles. The paddle must be repeatedly manipulated, often thousands of times during each use, and weight has a cumulative effect on the effort that is demanded of the user of the paddle. 
   It would be advantageous to attach the shaft to the blade of paddles in a manner which reduces weight and which does not add to the cost of manufacture by requiring a bulky and complex molded blade. 
   The present invention is directed to overcoming one or more of the problems discussed above. 
   BRIEF SUMMARY OF THE INVENTION 
   In one aspect of the present invention, a paddle for propelling and maneuvering a boat includes a paddle blade and a shaft having a handle portion of tubular shape which extends from a first end of the blade. An integral tongue portion of the shaft extends longitudinally from the handle portion along one of the major surfaces of the blade. The tongue portion has a curved cross section thereby forming a chamber which extends longitudinally along the major surface of the blade. A filler member extends along the surface of the blade within the chamber, the filler member being adhered to the tongue portion of the shaft and also being adhered to the surface of the blade to secure the shaft to the blade. 
   In another aspect of the invention a paddle for manually propelling and maneuvering a boat includes a blade having oppositely facing major surfaces and a tubular shaft having a handle portion extending from the blade at a first end thereof. A tongue portion of the shaft extends longitudinally along one of the major surfaces of said blade, the tongue portion having an elongated opening extending along a sidewall of the shaft which opening faces the surface of blade. A filler member within the tongue portion of the shaft extends along the surface of the blade at the opening. The filler member is adhered to the tongue portion of the shaft and is also adhered to the surface of the blade to secure the shaft to the blade. 
   In still another aspect the invention provides a method of manufacturing a paddle for use with small watercraft. Steps in the method include forming a paddle blade having oppositely facing major surfaces extending between ends of the blade. A paddle shaft is formed by cutting an opening in the sidewall of a portion of a tubular member which opening extends longitudinally along the tubular member and which extends to an end of the tubular member. This forms a tongue portion on the tubular member which tongue portion has a concave side forming an elongated chamber. A filler member is disposed in the chamber and is proportioned to extend longitudinally along the tongue portion of the shaft. The tongue portion of the shaft including the filler member is seated against one of the major surfaces of the blade. The filler member is adhered to the tongue portion of the shaft and is also adhered to the surface of the blade to secure the shaft to the blade. 
   Thus the invention enables economical manufacture of light weight, high strength paddles which do not require bulky blades having molded sockets for the purpose of attaching handles to the blades. 
   The invention, together with further objects and advantages thereof, may be further understood by reference to the following detailed description of the invention and by reference to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     In the accompanying drawings: 
       FIG. 1  is a frontal view of a paddle construction embodying a first example of the invention. 
       FIG. 2  is a side view of the paddle construction of  FIG. 1 . 
       FIG. 3  is a cross section view of the paddle construction of the preceding figures taken along line  3 — 3  of  FIG. 1 . 
       FIG. 4  is a foreshortened view of a paddle shaft component of the paddle construction of the preceding figures, the paddle shaft being shown as it appears prior to fastening of the paddle blade to the shaft. 
       FIG. 5  is a longitudinal section view of a portion of the paddle construction of the preceding figures taken along line  5 — 5  of  FIG. 1  and showing a rivet connection of the blade and shaft member of the paddle construction. 
       FIG. 6  is a longitudinal section view corresponding generally to  FIG. 5  but showing an alternate form of rivet connection 
       FIG. 7  is a frontal view of a paddle construction depicting a second example of the invention. 
       FIG. 8  is a cross section view of the paddle construction of  FIG. 7  taken along line  8 — 8  of  FIG. 7 . 
       FIG. 9  is a longitudinal section view of a portion of the paddle construction of  FIG. 7  taken along line  9 — 9  of  FIG. 7   
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIGS. 1 and 2  of the drawings, a paddle  11  in accordance with this embodiment of the invention has a paddle blade  12  with oppositely facing major surfaces  13  and  14  extending between first and second ends  16  and  17  of the blade. A shaft  18  extends from the first end  16  of the blade  12  to enable grasping and maneuvering of the paddle  11 . The blade  12  may have any of the outlines that are customary in paddles for small watercraft such as canoes and kayaks and need not have any bulky molded protruding regions for the purpose of providing a socket for seating the shaft  18 . 
   The blade  12  of this particular example is thermoformed from flat stock to have a slight curvature when viewed from the side but can, if desired, be a strictly flat element. The blade  12  is preferably formed of one of the light weight high strength plastics that are known to the art which in this example is ABS (acrylonitrile butadiene styrene) plastic. 
   Shaft  18  has a handle portion  19  which extends from end  16  of the blade  12  and which is continuous with an elongated tongue portion  21  of the shaft that extends longitudinally along the adjacent major surface  13  of the blade. The tubular handle portion  19  has a length that is dependent on the type of watercraft that the paddle  11  is to be used with. Canoe paddles, for example, are proportioned to be gripped at the distal end by one hand of the user while the other hand grips the shaft at a location which is relatively close to the blade  12 . Kayak paddles are longer and have blades  12  at each end of the shaft  18  which blades may be immersed in the water, alternately, at opposite sides of the hull of the kayak. The present invention is adaptable to paddles of any of these differing types. The tubular handle portion  19  should have an end closure (not shown) at the end which is remote from blade  12  to prevent entry of water as it is desirable that paddles float if they are accidentally dropped into the water. 
   Shaft  18  is formed from a high strength material which in this example is aluminum tubing. The shaft  18  may also be formed from various composites such as fiberglass tubing, for example. 
   Referring jointly to  FIGS. 2 ,  3  and  4 , the tongue portion  21  of shaft  18  is preferably of sufficient length to extend from the first end  16  of the blade  12  to a location which is adjacent to the opposite end  17  of the blade. The tongue portion  21  is formed by cutting away a strip of the sidewall of the tubing from which the shaft  18  is formed. This creates a slot opening  22  that extends longitudinally along the shaft  18  from handle portion  19  to the opposite end of the shaft. The tongue portion  21  of the shaft  18  which is formed by the cutting operation has a concave cross section and forms an elongated open chamber  23  which extends along the tongue and which is bounded on one side by the slot opening  22 . Blade  12  is subsequently seated against the slot opening  22  and chamber  23 . The cut which is made to form the slot opening  22  may, if necessary, have a small curvature in the region which is near the handle portion  19  to conform with curvature of the adjacent portion of blade  12  and the region of tongue portion  21  which is further away from the handle portion may be bent as may be necessary to conform with any curvature of the adjacent part of the blade. The cut which is made to form the opening  22  may be a straight cut if the blade has a strictly flat configuration. 
   Referring to  FIGS. 1 to 4 , filler member  24  is disposed within chamber  23  and has a size and shape conforming to the size and shape of the chamber. Thus the outer surface  26  of the filler member  24  is situated at the slot opening  22  and extends along the opening. The filler member  24  may be preformed and be secured to the chamber wall with an adhesive  25  after it is inserted into the chamber  23 . Alternately the filler member  24  may be formed in place by filling the chamber  23  with one of the known adhesive plastic materials, such as expanding polymeric foam, which can be cured and solidified after it has been emplaced in the chamber. 
   The end of tongue portion  21  which is remote from the handle portion  19  is reinforced by an end cap  27  which extends a short distance into the end of chamber  23  and which has a flat surface  28  that is continuous with the outer surface  26  of filler member  24 . End cap  27  provides for installation of a fastener as will hereinafter be described. In this example end cap  27  is formed of rigid PVC (polyvinyl chloride), the filler member  24  being formed from PVC foam which is cemented in place and then sanded to assure that the outer surface  26  of the filler member is flush with the edges of chamber  22 . Preferably, the filler member  24  is cemented into tongue portion  21  with expanding urethane foam adhesive  25 . 
   Blade  12  is seated against surface  24  of the filler member  14  and surface  28  of end cap  27 , after an adhesive  29  is applied, to secure the blade to the shaft. The adhesive  29  in this example is an ABS and PVC compatible solvent cement although other adhesives may also be used. 
   Preferably, mechanical fasteners are provided to reinforce the attachment of the blade  12  to shaft  18 . A first such fastener, which is a standard rivet  31  in this example, is implanted at an opening  32  which penetrates through the tip of tongue portion  21 , end cap  27  and the blade  12 . Referring to  FIG. 5 , a second fastener is a blind rivet  42  which extends through the blade  23  and through the adjacent wall of handle portion  19  and shaft  18  a location close to the end of blade  12 . Referring to  FIG. 6 , the blind rivet may be replaced with another standard rivet  33  which penetrates completely through the handle portion  19  of the shaft if a rigid cylindrical fitting  34  is disposed within the handle portion at the location of the rivet  33 . Fitting  34 , which may be formed of rigid PVC for example, enables the tubular shaft  18  to withstand the compressive forces which are exerted during installation of a standard rivet. 
   It has been pointed out that the filler member through which the blade is secured to the tubular shaft can be a preformed rigid member which is inserted into the shaft. Referring jointly to  FIGS. 7 ,  8  and  9 , the filler member  24   a  can also be a composite of two or more types of materials. In this example, the central portion of the filler member  24   a  is an insert  36  which has been preformed from solid high strength plastic. Insert  36  is shaped to extend between blade  12  and the inside wall of tongue portion  21  of shaft  18  but is not as wide as the chamber  23  which is formed by the tongue portion. The portions of chamber  23  which extend along each side of insert  36  are filled with hardenable plastic foam  37  which is cured after emplacement in the chamber. Insert  36  preferably has a series of transverse passages  38  into which the plastic foam  37  extends to interlock the two materials to each other. 
   Referring to the drawings in general, the invention provides for a light weight economically manufactured paddle construction as the blade  12  may be a plastic component but need not be a complex molded plastic component formed with a bulky socket for the purpose of receiving and seating a handle. In many cases, the blade can be formed from low cost plastic sheet stock. The simplified attachment of the blade and handle to each other provides a very high strength paddle and is adaptable to paddles of diverse different types. 
   While the invention has been described with reference to certain particular embodiments for purposes of example, many variations and modifications of the paddle construction are possible and it is not intended to limit the scope of the invention except as defined by the following claims.