Ergonomic kayak paddle

A kayak paddle with a generally straight shaft that is preferably about 0.7 inches in diameter, the shaft is also conically tapered at either end. A left hand grip and a right hand grip are mounted on the shaft, and there is a blade at either end of the shaft. The blades each have a conically tapered socket to accept the tapered ends of the shaft. A portion of the socket remains vacant when the shaft is fully inserted, the vacant portion of the socket serves to trap sufficient air to ensure that the paddle will float. The mechanical connections thus formed prevent the shaft from rotating in the blade sockets and also minimize the amount of stress placed on the adhesive used to fix the shaft in the sockets. The grips ensure that the user's hands can be consistently placed and oriented on the shaft; because of the small diameter of the shaft, the user's hands can easily encircle the grips, and the user is thereby afforded a high degree of control over the paddle. Further, the grips are contoured so as to more ergonomically position the user's hands at natural gripping angles, with respect to the horizontal axis of the shaft; the natural gripping angles serve to minimize stresses on the user's wrists, hands, and arms. Additionally, the contours of the grips substantially prevent the user's hands from sliding along the shaft, and prevent the shaft from rotating in the user's hands. Finally, the grips have knuckle guards, preferably integrally formed with the grips, which serve to protect the user's hands in the event of an impact with obstructions such as rocks or trees.

BACKGROUND OF THE INVENTION
 1. The Field of the Invention
 The present invention relates generally to kayak paddles and particularly
 relates to an improved kayak paddle having an ergonomic grip arrangement
 to facilitate consistent and comfortable placement and orientation of the
 user's hands on the paddle.
 2. The Relevant Technology
 Kayakers exhibit a wide range of skill levels, from the recreational
 kayaker to the professional competitor. Kayaking enthusiasts pursue their
 sport in a variety of settings, including creeks, rivers, and the ocean.
 Each of the settings presents unique challenges to the kayaker. In creeks
 and rivers, the kayaker often faces swift currents, rapids, boulders, and
 snags. The sea kayaker may encounter strong tides, riptides, and high
 winds. These obstacles can present a serious threat to the safety of the
 kayaker who is ill-prepared to meet them.
 In order to overcome these obstacles, it is essential that the kayaker be
 able to effectively control the kayak with a minimum of effort; this is no
 less true for the recreational kayaker than it is for the expert. The
 essential element in kayak control is the kayak paddle. A kayak paddle
 that the user can easily and efficiently employ will greatly facilitate
 control of the kayak.
 It is generally acknowledged that the orientation of the kayaker's grip on
 the shaft of the kayak paddle is a critical factor in the useability and
 efficiency of kayak paddles. Accordingly, past efforts have been directed
 towards developing a shaft so formed as to provide the kayaker with a
 useful gripping means.
 One common configuration is a round shaft that has been compressed in two
 places so as to deform the round cross-section, at those points, into
 generally oval-shaped cross-sections. The purpose of the oval cross
 sections is to provide regions where the user can more easily grasp the
 shaft. The oval grip portions are also intended to help visually indicate
 the points on the shaft where the user's hands should be placed. Finally,
 the grip portions aim to assure the user that the blades will be in the
 same position each time the grips are engaged, because the radial location
 of the grip portions, relative to the blades, is fixed.
 Another typical configuration employs a round shaft with shims located on
 the shaft where the users's hands should be placed. The shims are
 typically secured in place on the shaft by something akin to a shrink wrap
 process. As with the oval-shaped sections discussed above, the purpose of
 the shims is both to facilitate gripping of the shaft, to help visually
 indicate where the user's hands should be placed, and to provide some
 assurance that the blades will be consistently positioned.
 Finally, a more radical design uses a generally straight shaft which has
 bent portions near either end to provide gripping regions for the user's
 hands. The bent shaft has a generally round cross-section which flattens
 slightly through the gripping regions.
 Although prior efforts have resulted in some improvement of the kayaker's
 grip on the shaft, each suffers from inadequacies. The oval cross-section
 and shim-type grip designs somewhat improve the kayaker's grip and help
 indicate where the kayaker's hands should be placed, but do little to
 prevent the user's hands from sliding longitudinally on the shaft. When
 the kayaker's hands are free to slide along the shaft, control and use of
 the paddle become very difficult, particularly in rough conditions such as
 rapids or whitewater. Even in calm conditions, the kayaker's hands tend to
 slide down the shaft during the draw stroke, that is, the stroke wherein
 the kayaker reaches forward with the shaft, dips the blade into the water
 and pulls, or draws, the shaft down and back. Because they are free to
 slide, the kayaker's hands tend to slip down the shaft during the draw
 stroke, rather than to push the shaft down into the water. Naturally, the
 problem of hand slippage is further aggravated when the shaft is wet, as
 is commonly the case. Hand slippage and the resulting loss of paddle and
 kayak control is a source of frustration for beginners and experts alike.
 While the bent shaft grip configuration is somewhat more effective at
 reducing hand slippage than are the oval and shim-type grip configurations
 commonly used on straight shafts, the problem of hand slippage still has
 not been adequately addressed.
 Another shortcoming of typical kayak paddle grip designs is the problem of
 shaft rotation. Shaft rotation occurs when kayak paddle blades are
 subjected to the forces exerted by wind and water; those forces act
 against the flat part of the blade, thereby imparting to the shaft a
 tendency to rotate about its longitudinal axis.
 Shaft rotation is undesirable because it necessarily causes the blades,
 fixed to the ends of the shaft, to rotate out of position. Physically
 strong users can prevent this rotation to some extent by tightly gripping
 the shaft. However, gripping the shaft tightly to prevent rotation often
 involves a considerable expenditure of effort on the part of the user who
 is kayaking in strong currents and/or high winds, conditions commonly
 encountered by kayakers. In the more likely scenario, the user is unable
 to resist shaft rotation and is compelled to rotate the shaft to place the
 blades back into position. The necessity for frequent re-orientation of
 the shaft is, at least, a source of frustration, and could amount to a
 dangerous distraction in challenging conditions such as whitewater,
 rapids, or riptides.
 The oval and shim-type grip designs provide little resistance to the
 shaft's inherent rotational tendency because their cross-sections are
 substantially similar to a purely circular cross-section, which offers
 virtually no impediment to shaft rotation. Nor does the bent shaft grip
 configuration resolve the problem of shaft rotation; the gripping regions
 of the bent shaft have a cross-section similar to that found in the oval
 and shim-type grip configurations and thus possess the same inherent lack
 of resistance to shaft rotation.
 The inability of current designs to minimize or prevent shaft rotation,
 causes the user to lose a large measure of control over the paddle, and
 thus, over the kayak. Furthermore, by expending time and effort to
 frequently rotate the shaft back into position, the user also realizes an
 overall reduction in paddling efficiency. Lack of paddle and kayak
 control, and reduced paddling efficiency, inevitably result in user
 frustration and fatigue. Fatigue in particular, can become an important
 issue, for example, when the user is kayaking in open water and has to
 contend with strong tides and wind.
 Kayak paddle shaft rotation, considered alone, is ample cause for concern
 to the kayaker. However, the natural and inevitable consequence of shaft
 rotation, out-of-position blades, is cause for concern as well. Blades
 which are out of position present a serious problem because they impede
 the kayaker's ability to respond to rapidly changing conditions. As an
 example, a kayaker whose craft is rushing towards a rock may have only a
 second or two to take evasive action; if the paddle blades are out of
 position, the kayaker may be unable to timely execute the necessary
 maneuvers. Thus, kayakers must be able to quickly establish and easily
 maintain consistent blade orientation. Current kayak paddle grip designs
 do not meet this need.
 Hand slippage and shaft rotation are the major unresolved concerns in the
 field, but there are a number of other problems that existing designs have
 not adequately addressed, or have not addressed at all. One such problem
 is that the typical grip design does little to reduce the often
 substantial stresses that kayaking places on the user's hands, wrists, and
 arms. If anything, these designs may tend to aggravate the problem. One
 reason for this is that the typical grips are relatively large in diameter
 and thus, difficult to grasp and hold. The shim-type grips are
 particularly bulky to grasp because the shim increases the diameter of the
 grip region, making the shaft difficult for the user to securely hold.
 Thus, the user is forced to grip the shaft tightly in order to be able to
 hold it; the user's tight grip consequently increases the stresses on the
 user's hands, wrists, and arms.
 Not only does their bulk make typical grip configurations troublesome to
 grip and hold, but those configurations also force the user to grip along
 an unnatural horizontal line. Because most users' natural grip is along
 axes slightly oblique to a horizontal line, the horizontal grip induces
 unnecessary additional stress on the user's wrists, hands, and arms.
 The grip spacing, that is, the space between the points at which the user
 grips the shaft, of typical grip arrangements also tends to force many
 users' hands and arms into unnatural positions. This is because the grip
 spacing in typical kayak paddle grip arrangements is generally calculated
 to provide a one-size-fits-all configuration; such designs are inherently
 unsuited to meet the ergonomic requirements of many users. Consequently,
 many users are forced to assume inefficient, unnatural postures on the
 shaft.
 In sum, the bulky grips, generic grip spacing, and unnatural grip positions
 of the typical kayak paddle grip arrangements all conspire to impose
 unnecessary stresses on the user's hands, wrists, and arms. The results of
 this stress range from fatigue to repetitive-use injuries that require
 medical treatment.
 A different type of problem with typical kayak paddle grip arrangements
 concerns the production processes by which those arrangements are
 fabricated. The bent shaft configuration is noteworthy in this regard. The
 air-bag inflated mold process used to produce bent shafts is complex and
 time-consuming. This type of production arrangement is not well-suited to
 rapid, high volume, mass production. Consequently, bent shaft kayak
 paddles are very expensive and thus practically unavailable to many
 kayakers.
 Oval section and shim-type grip arrangements are somewhat simpler to
 manufacture than bent tubes, but as indicated earlier, involve a number of
 additional steps beyond the creation of a simple shaft. These additional
 steps necessarily increase the cost of these types of kayak paddle shafts.
 Not only are these grip arrangements labor-intensive and expensive to
 produce, but they also fail to make any provision for ergonomically
 positioning the user's hands on the shaft.
 A final concern in the field of kayak paddles relates to the adhesive bond
 between the shaft and the blade socket in which it is inserted. It is the
 case with some designs that the stresses imposed on the paddle blades may
 break the adhesive bond between the shaft and the socket of the paddle
 blade in which the shaft is inserted. When the adhesive bond is broken,
 the shaft and blade are free to rotate with respect to each other, and the
 paddle is thereby rendered ineffective. The paddle must then be repaired
 or replaced.
 SUMMARY AND OBJECTS OF THE INVENTION
 It is a general object of the present invention to provide an improved
 kayak paddle to solve the aforementioned problems.
 Accordingly, it is an object of the present invention to provide an
 improved kayak paddle with an ergonomic grip arrangement that facilitates
 consistent placement and orientation of the user's hands on the kayak
 paddle shaft.
 It is similarly an object of the present invention to provide an improved
 kayak paddle with an ergonomic grip arrangement which, when engaged by the
 user, orients the user's hands along natural gripping axes.
 It is an additional object of the present invention to provide an improved
 kayak paddle with an ergonomic grip arrangement that, when gripped by the
 user, substantially prevents the kayak paddle shaft from rotating in the
 user's hands.
 It is finally an object of the present invention to provide an improved
 kayak paddle with an ergonomic grip arrangement that, when engaged by the
 user, substantially prevents the user's hands from sliding along the
 longitudinal axis of the shaft.
 Other objects and advantages of the invention will become apparent upon
 reading the following detailed description and appended claims, and upon
 reference to the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
 The present invention relates to an improved kayak paddle with an ergonomic
 grip arrangement. FIGS. 1 through 6 show an ergonomic grip arrangement
 according to a preferred embodiment of this invention.
 With reference to FIG. 1, a kayak paddle according to the present invention
 is depicted generally as 10. An ergonomic grip arrangement depicted
 generally as left hand grip element 12 and a right hand grip element 14
 are mounted about an elongate shaft 16 having a first end 18 and a second
 end 20. In a preferred embodiment, elongate shaft 16 has a generally
 circular cross-section; however, elongate shafts having square, oval, or
 polygonal cross-sections, or combinations thereof, are also contemplated
 as being within the scope of this invention as indicated in FIGS. 1B, 1C,
 and 1D. Note that the left hand grip element 12 and the right hand grip
 element 14 are identical to each other in form and construction, but have
 been assigned different numbers in the interest of clarity. In a preferred
 embodiment, suitable means for securing the right hand grip element 14 and
 the left hand grip element 12 to the elongate shaft 16 include adhesive,
 double-backed tape, or the like. As indicated generally in FIG. 1, the
 left hand grip element 12 and the right hand grip element 14, when mounted
 about the elongate shaft 16, are axially distanced from the first end 18
 of the elongate shaft 16 and the second end 20 of the elongate shaft 16,
 respectively, substantially equal distances. The outside diameter 34 (FIG.
 3) of elongate shaft 16 is well-adapted to permit the user's hands to
 substantially encircle the left hand grip element 12 and the right hand
 grip element 14, respectively, when the left hand grip element 12 and the
 right hand grip element 14 are mounted about the elongate shaft 16; in a
 preferred embodiment, the outside diameter of the elongate shaft is in the
 range of about 0.6 inches to about 0.8 inches.
 While a range of shaft diameters from about 0.6 inches to about 0.8 inches
 represents the preferred embodiment, this range should not be construed as
 a limitation; this invention contemplates yet smaller diameter shafts as
 improvements in materials and manufacturing processes are realized.
 Further, as technology progresses in the area of grip materials and
 manufacturing, it is also contemplated that the circumference of the grip
 elements may be reduced, thereby permitting correspondingly larger shaft
 diameters. Thus, shafts having diameters outside the preferred indicated
 range are considered to be within the scope of this invention.
 Finally, with regard to the shape of the shaft, the preferred embodiment
 contemplates a substantially straight shaft. However, it is recognized
 that the grip elements may also be effectively employed if mounted on
 shafts which have hand-locating offsets; the offsets cooperating with the
 grips so as to locate the user's hands along the shaft, and orient the
 user's hands about the shaft, respectively. Accordingly, an offset shaft
 employing ergonomic grips is considered to be within the scope of this
 invention.
 Attached to the elongate shaft 16 are two blades 22; one blade 22 is
 attached to the first end 18 of the elongate shaft 16, and one blade 22 is
 attached to the second end 20 of the elongate shaft 16. In the interest of
 clarity, the blades and grips of FIG. 1 are shown as being generally
 rotationally symmetric. However, those of skill in the kayaking art
 appreciate that left and right blades are generally not planar with each
 other; in fact, the left and right side blades and grips are typically
 rotationally offset several degrees from one another as indicated in FIG.
 1A. Such rotational offset 23 between left and right side grips and blades
 is contemplated and is within the scope of the present invention. In a
 preferred embodiment, the rotational offset is in the range of about 45
 degrees to about 90 degrees.
 The left hand grip element 12 and the right hand grip element 14 are in
 accord with FIG. 3. Note that while FIG. 3 depicts only the left hand grip
 element 12, the right hand grip element 14 (not shown) is similarly
 mounted about the elongate shaft 16, opposite the left hand grip element
 12, as indicated generally in FIG. 1. As indicated in FIG. 3, the left
 hand grip element 12 has a generally cylindrical bore therethrough so as
 to facilitate mounting about the elongate shaft 16, the cylindrical bore
 being coaxial with the longitudinal axis of the elongate shaft 16. When
 the left hand grip element 12 and the right hand grip element 14 are
 mounted about the elongate shaft 16, hand-orienting indentations depicted
 generally as notches 32, generally having a vertex, serve to seat the left
 and right index fingers, respectively, of the user. Thus, the user's hands
 can be consistently placed and oriented on the elongate shaft 16 by touch
 alone. Furthermore, the notches 32 serve to desirably prevent the user's
 hands from sliding in either direction along the longitudinal axis of
 shaft 16. The notches 32 also cooperate with contours 26, 28, and 30 to
 desirably prevent the shaft 16 from rotating in the user's hands.
 FIGS. 3 and 6 depict the left hand grip element 12 and corresponding grip
 axis 48. While not shown in FIGS. 3 and 6, the right hand grip element 14
 and the corresponding grip axis 48 are similarly disposed with respect to
 each other. Given these similarities and the fact that, as pointed out
 earlier, the left hand grip element 12 and the right hand grip element 14
 are identical to each other in form and construction, the respective
 features of the left hand grip element 12 and the right hand grip element
 14 will henceforth be referred to in the plural where necessary for
 clarity.
 As indicated by FIGS. 3 and 6, the contours 26, 28 and 30 serve to position
 the user's hands along the user's natural grip axes 48, rather than along
 an unnatural horizontal line 46. The natural grip axes 48 are generally
 oblique to the horizontal line 46, so as to form acute angles 50. By
 positioning the user's grip along natural grip axes 48, the contours 26,
 28, and 30 of the left hand grip element 12 and the right hand grip
 element 14 thereby significantly reduce stress on the user's hands, wrists
 and arms. In a preferred embodiment, the acute angles 50 are in the range
 of about 6 degrees to about 8 degrees, however, other angles including 0
 degrees as well as exaggerated aggressive angles are contemplated within
 the scope of the present invention. Note that the acute angle 50, as
 generally depicted in FIG. 6, is exaggerated for the sake of clarity and
 should not be construed to be limited to the extent shown.
 Finally, regarding construction of the ergonomic grip arrangement, the
 preferred embodiment of the left hand grip element 12 and the right hand
 grip element 14 permits the user's hands to substantially encircle the
 grips. However, ergonomic grips of larger circumference may be desired by
 some users for particular applications and are thus also contemplated as
 being within the scope of this invention.
 In an alternate embodiment, knuckle guards 40, depicted generally in FIG.
 4, serve to protect the user's hands in the event of impact with rocks,
 branches or other obstacles that a kayaker may encounter, as well as
 further serving to properly orient the user's hands on the paddle. Knuckle
 guards 40 are preferably removably attachable to the ergonomic grip
 arrangement. It will be readily appreciated by those of skill in the art
 that the aforementioned removability feature may be effectuated by a
 variety of known devices including, but not limited to, screws, pins,
 clamps, and the like. As indicated in FIG. 4, the shield members 38 are
 joined to the left hand grip element 12 and the right hand grip element
 14, respectively, by attachment members 36. In a preferred embodiment,
 attachment members 36 comprise clamps or the like, as indicated in FIGS. 4
 and 4A. As further indicated in FIG. 4, the shield members 38 project
 outwardly so as to readily permit the user's hands to engage the left hand
 grip element 12 and the right hand grip element 14. The shield member as
 depicted in FIG. 4 shows a shield member having two points of attachment
 with the elongate shaft 16. It is contemplated that shield members may
 assume an L-shaped configuration and be attached to the shaft at only one
 point or may even be integrally formed with grip 12 as a single molded or
 assembled unit. Such embodiments are contemplated within the scope of the
 present invention.
 Finally, as indicated generally in FIG. 1, the blades 22 are fixedly
 attached to either end of the elongate shaft 16. In a preferred
 embodiment, each of the blades 22 has a hollow rib 52 formed therein, as
 indicated in FIG. 7. The hollow rib 52 extends substantially the length of
 the blade 22. The hollow rib 52 has a socket portion 54 to receive the
 first 18 and second 20 ends of the elongate shaft 16, the shaft ends being
 secured in the socket portions 54 by adhesive or the like. Adjacent to the
 socket portion 54, and communicating therewith, is a tapered chamber
 portion 56. The tapered chamber portion 56 serves to confine a quantity of
 air when the first 18 and second 20 ends of the elongate shaft 16 are
 inserted fully into the socket portions 54; the air thereby entrapped
 serves to facilitate flotation of the kayak paddle. Preferably, socket
 portions 54 are in the range of about three (3) inches long to about five
 (5) inches long, and tapered chamber portions 56 are in the range of about
 ten (10) inches long to about twelve (12) inches long.
 In an alternate preferred embodiment, suitable means for fixedly attaching
 the blades 22 to the elongate shaft 16 include use of tapered shaft ends
 24, in accord with FIG. 2, and blade sockets 42 which terminate in tapered
 ends 44, in accord with the cutaway drawing of FIG. 5. When the tapered
 shaft ends 24 (FIG. 2) are inserted into the sockets 42 (FIG. 5), the
 tapered shaft ends 24 mate with the tapered socket ends 44 (FIG. 5). In a
 preferred embodiment, suitable means for fixedly attaching the blades
 includes securing the tapered shaft ends 24 in the sockets 42 with the use
 of adhesive or the like. The tapered shaft ends 24 cooperate with the
 tapered socket ends 44 to ensure structural integrity of the connection,
 to minimize stress on the adhesive joint, and to effectively prevent
 rotation of the elongate shaft 16 and the paddle blades 22, with respect
 to each other.
 It is also contemplated that as a result of the diverse individual physical
 parameters of kayakers and kayaks (e.g., shoulder width, preferred grip
 spacing, kayak width, kayak height above waterline, etc.), the present
 invention may be packaged as a kit of individual elements for assembly
 either by the end user or by a intermediary equipment retailer. Such
 collection of assembleable components is contemplated within the scope of
 the kayak paddle kit invention.
 The present invention may be embodied in other specific forms without
 departing from its spirit or essential characteristics. The described
 embodiments are to be considered in all respects only as illustrative and
 not restrictive. The scope of the invention is, therefore, indicated by
 the appended claims rather than by the foregoing description. All changes
 which come within the meaning and range of equivalency of the claims are
 to be embraced within their scope.