Pontoon water bike
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to improvements to small, human powered water craft, and particularly to one man pontoon rafts propelled by pedal-driven paddle wheels. 
     2. Description of Related Art 
     Small water craft used primarily for recreational fishing include two major types. These include dugouts, such as canoes and pirogues, which have high gunnels partially enclosing cargo or passengers located near the water line, and rafts, such as catamarans, where flotation devices such as pontoons support a superstructure above water on which ride both cargo and means for locomotion. 
     Various rafts in the prior art employ two parallel pontoons between which a deck spans to support one or more upright seats for fishermen. Means of propulsion may include electrically or manually driven propellers below the water line. Steering may include means for directing the propeller, or it may comprise a rudder system. Such systems often require complex transmission systems to transform axial rotation in one direction to another direction for driving the propeller. Others using electrical or gasoline motors are correspondingly heavier and more costly and require that finite quantities of fuel or batteries be carried on board. A need exists for an inexpensive, light weight raft easily propelled and steered by human effort. 
     Small fishing rafts usually occupy space amounting to several multiples of the cargo the raft can carry. This is due often to the spread base and vertical superstructure so common for such watercraft which often is larger than the bed of a typical pickup truck. Handling such bulky and voluminous rafts requires either a trailer or means for disassembling the craft for transportation and storage. Complexity of assembly often discourages routine disassembly to users. A need exists for a light watercraft which easily can be disassembled for transportation and storage. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of this invention to provide a light-weight water raft which easily and quickly can be assembled for use and disassembled for transportation and storage. 
     It is another object of this invention to provide a small water raft which is inexpensive to acquire and maintain. 
     It is another object of this invention to provide a water raft relying upon one of its pontoons for stabilized steering. 
     It is yet another object of this invention to provide a water raft which easily can be propelled by human effort. 
     The foregoing and other objects of this invention are achieved by providing a water bike raft comprising two rear pontoons disposed parallel one another on either side of a longitudinal axis, a transverse, planar truss spanning between them. Coupled by quick release means to the midpoint of the truss and extending forward to rest on a third, front pontoon, a vertical frame supports a swivel seat for a driver. The frame includes a tilted steering column similar to that of a conventional bicycle, allowing steering the water bike by turning the front pontoon. To propel the water bike, the driver manipulates a foot pedal mounted near the steering column and coupled by a chain to a transverse axle beneath the seat. Coupled to the axle are a plurality of planar water paddles arranged around a hub. The water bike quickly can be disassembled by uncoupling the frame from the truss and from the front pontoon, uncoupling the rear pontoons from the truss, and removing the paddle wheels from the axle. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features believed characteristic of the present invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use and further objects and advantages thereof, will best be understood by reference to the following derailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
     FIGS. 1 &amp; 3 depict side and front elevational views respectively, and FIG. 2 depicts a plan view, of a preferred embodiment of the water bike having cylindrical pontoons. 
     FIG. 4 shows a partial side elevation similar to FIG. 1 derailing the water bike frame and pedal assemblies. 
     FIG. 5A &amp; 5B detail in plan and side elevational views respectively the mounting plate on the pontoons, with the quick release lock shown poised for insertion therein. Corresponding FIGS. 6A &amp; 6B show the lock inserted into the mounting plate and locked. 
     FIG. 7A through 7D detail in cross section, fragmentary section, exploded section and right side elevation, respectively, a paddle wheel assembly propulsion system of the preferred embodiment of FIG. 1. 
     FIGS. 8A, 8B &amp; 8C detail quick release joints coupling front and rear portions of the frame shown in FIG. 4. 
     FIG. 9 derails a seat adjustment mechanism in partial cross section as indicated in FIG. 4. 
     FIG. 10 details a steering mechanism coupler of FIG. 4. 
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
     With reference now to the figures, and in particular to FIGS. 1-3, water bike A includes three generally cylindrical pontoons 8, 18 bearing fins 8a on their bottom sides and mounting plates 8b on their top sides, the pontoons 8, 18 shown floating level and partially submerged below water surface W. Rear pontoons 8 are disposed parallel one another on opposite sides of and equidistant from longitudinal axis L, while third, front pontoon 18 is positioned forward of rear pontoons 8 and centered on axis L. Spanning between rear pontoons 8, truss means 12 couples to pontoons 8, 18 at mounting plates 8b and forms a support frame fixing rear pontoons 8 in position. 
     Coupled to truss 12 substantially at axis L, vertical frame 3 extends horizontally forward along axis L to terminate in steering housing 20 positioned above front pontoon 18 and tilted slightly rearwardly. Steering shaft 22 rotates within housing 20 and extends downwardly therefrom to couple to front pontoon 18 at mounting plate 8b. Handle 24 extends upwardly from housing 20 opposite shaft 22 and then angles rearwardly toward seat 9, mounted atop frame member 3d. Handle 24 terminates in T-grip 1 disposed conveniently in front of a driver D (not shown) seated in seat 9. The rearward tilt of housing 20 minimizes the necessary length of handle 24, thereby also minimizing weight and cost. 
     As detailed in FIG. 10, steering handle 24 couples to shaft 22 within housing 20 similarly to the way some bicycle handlebars couple to their front wheel. Handle 24 and steering shaft 22 are tightly coupled together by nut 25 and extend through knurled collar 23 to rest on bearing 27 in the upper end of housing 20. Thus, handle 24 and steering shaft 22 are free to rotate within housing 20 while being locked firmly together. FIG. 10 also illustrates ring pin 26 mating with apertures 29 and biased into place by spring 28. Ring pin 26 and apertures 29 permit vertical adjustment of handle 24 and T-grip 1 for the comfort and convenience of driver D. Handle 24 also may be removed altogether in this fashion when water bike A is disassembled for transportation or storage. 
     Pontoons 8, 18 are interchangeable (the different reference numerals serving herein merely for convenience in distinguishing front and rear pontoons), symmetrical about transverse axis C, and streamlined in shape for efficient movement through water. Pontoons 8, 18 preferably are hollow, air tight cylinders formed from extruded or molded plastic, such as rigid, cross linked polyethylene, known for light weight and strength. One having ordinary skill in the art will recognize that other materials could be substituted, such as aluminum or steel, with consequences of added weight and cost. Further, other pontoon systems, such as styrofoam floats, could be employed without departing from the spirit and scope of the present invention. Mounting plates 8b on pontoons 8, 18 are offset a select distance K from centerlines C toward seat 9 so that pontoons 8, 18 do not support the weight of frame 3 at centerlines C. 
     Driver D steers water bike A by moving T-grip 1 transversely to axis L, causing front pontoon 18 to become re-positioned non-parallel to axis L, as shown in FIG. 3. Thus, pontoon 18 serves as a rudder for water bike A. Further, offset K creates a novel means of stabilizing the steering of water bike A similar to the positive steering effect of power steering in automobiles. As mounted for straight running parallel axis L, front pontoon 18 is substantially level in water W (FIGS. 1 &amp; 2 and phantom in FIG. 3). When driver D turns front pontoon 18 out of alignment with axis L either left or right, offset K and the tilt of housing 20 cause the forward end of front pontoon 18 to be forced deeper into the water than the rearward end thereof (FIG. 3). Because pontoon 18 is buoyant, this front-to-back differential is unstable, and pontoon 18 naturally rights itself and realigns with axis L when driver D releases T-grip 1. Thus, the most stable position of front pontoon 18 is parallel to axis L, resulting in a positive steering effect. This effect occurs whether water bike A is moving or not, and whether or not it is moving forward or backward. 
     FIGS. 5A, 5B and 6A, 6B detail quick release locks 7 which couple water bike A to pontoons 8, 18. Mounting plates 8b preferably are steel and curved to match the upper surface of pontoons 8, 18, and are attached thereto by screws, rivets or other suitable means. Shoe 8c protrudes upwardly from the center of plate 8b to form a recess beneath 8c in which is received foot 7a of quick release lock 7. Shoe 8c includes stop 8d against which abuts ankle 7b of lock 7. Cam lock 7c bears against shoe 8c to affix lock 7 in place. In this position, toe end 7d of foot 7a mates with reinforcing shoe 8e made in similar fashion to shoe 8c, and provides resistance against overturning moment from lock 7. One having ordinary skill in the art will recognize that reinforcing shoe 8e could be made integral with shoe 8c or omitted altogether, as appropriate for strength and weight considerations. 
     Turning now to FIGS. 1, 2 and FIG. 4, truss 12 further comprises horizontal truss member 12a spanning between pontoons 8. Coupled to horizontal truss member 12a, arched truss member 12b extends upwardly and tilts forwardly toward front pontoon 18. Truss extension members 12c, 12d extend forward along axis L from truss members 12a, 12b respectively to couple to frame 3 by quick release joints 11 mounted to the ends of upper and lower frame members 3b, 3a and discussed in detail below. 
     Frame 3 comprises two tubular frame portions disposed vertically one above the other and extending forward from truss 12 along axis L and tied together approximately beneath seat 9 by tie member 3c. Neither of these upper and lower frame portions are straight their entire length. Lower frame member 3a extends approximately half way to front pontoon 18 and then angles upwardly to steering shaft housing 20. Disposed above lower frame member 3a, forward frame member 3d extends rearwardly from housing 20 to couple to upper rear frame member 3b through offset bracket 3e forward of tie member 3c. Forward frame member 3d continues rearwardly above upper rear frame member 3b and beneath seat 20. 
     Frame 3 and truss 12 preferably are made from painted, circular steel tubing having a diameter of one and one-quarter (11/4&#34;) inches and sixteen gauge (16 ga.) wall thickness, or other tubing which offers the equivalent balance of lightness, strength and durability at an inexpensive price. Steel tubing also can be welded to eliminate a need for couplings to join tubular members. One having ordinary skill in the art will recognize that other tubular materials, such as aluminum, carbon or plastic piping, could be substituted without departing from the spirit and scope of this invention. 
     Seat 9, having base 9a, both of conventional design, mounts atop forward frame member 3d rearward of offset bracket 3e by a unique adjustable locking mount 30 detailed in FIG. 9. Seat base 9a preferably swivels for convenience in getting on and off of water bike A. Seat 9 swiveled to face rearward permits driver D to step directly off the rear of water bike A without having to negotiate stepping on or over rear pontoons 8 or paddle wheel assembly 60. This mounting approach also keeps driver D&#39;s weight substantially symmetric about axis L during mounting and dismounting, and the weight of frame 3 and front pontoon 18 offset driver D&#39;s weight which otherwise would tend to tip water bike A rearwardly. 
     Seat mount 30 comprises cylinder 31 to which base 9a of seat 9 is affixed. Cylinder 31 has an inside diameter slightly larger than the outside diameter of forward frame member 3d, allowing cylinder 31 to slide along the length of frame member 3d between offset bracket 3e and latch end 10. Plate 32 welded to cylinder 31 extends downward along side upper rear frame member 3b, where clamp means secures it by friction against member 3b. Specifically, bolt 34 carries head 38 adapted to bear against member 3b and cylinder 31 when knob 36 draws it through an aperture in plate 32. Knob 36 quickly can be unscrewed to release mount 30, allowing seat 9 to be adjusted forward or backward along member 3d. Latch end 10 includes suitable latch means, such as retractable spring pins which protrude through forward member 3d (not shown), to prevent mount 30 from inadvertently sliding off the end of member 3d during seat positioning. One having ordinary skill in the art will recognize that other clamping means or attachment means could be employed to affix seat 9 to frame 3 without departing from the spirit and scope of the present invention. 
     FIGS. 8A-8C detail quick release joints 11 which provide a quick and easy means of separating frame 3 and truss 12 for transportation and storage. FIG. 8A shows in longitudinally exploded view the various components of joint 11. Inner collars 11a are mounted to the ends of frame members 3a, 3b by forward protrusions 11j and include a plurality of radially disposed, conically tapered apertures lie adapted to receive and limit radial movement of spherical bearings 11d. Outer collar 11c surrounds inner collar 11a and bearings 11d, and concentric spring 11b biases outer collar 11c rearwardly over the top of bearings 11d, as shown in FIG. 8B. Annular groove 11h in inner collar 11a receives retainer ring 11i to prevent outer collar 11c from being forced off of inner collar 11a by spring 11b. 
     Outer collar 11c extends fully over bearings 11d when spring 11b is fully extended (FIG. 8B), thereby seating bearings 11d at their radial inner limit within apertures 11e. In this position, bearings 11d extend radially inward enough to reduce the inside diameter of inner collar 11a. Bearings 11d mate with groove 12e on truss extensions 12c, 12d, thereby coupling frame 3 to truss 12. Moving outer collar 11a forwardly and compressing spring 11b (FIG. 8C) positions the rearward end of outer collar 11a over bearings 11d, allowing them to be forced radially outward into recess 11g enough to extract extension 12c, 12d from within inner collar 11a, thereby decoupling truss 12 from frame 3. 
     Various other quick release joints could serve in lieu of joints 11 as frame quick release means. For example, simple pin and aperture joints coupling frame members 3a, 3b to extensions 12c, 12d could be configured similarly to ring pin means 15 shown in FIG. 10. Also, both joints 11 are not necessary. One could be replaced with a simpler, open ball-and-socket joint which would allow truss 12 to pivot relative to frame 3 when the remaining joint 11 is disengaged. Also, an internal biasing spring (not shown) could be included within quick release joint 11 to pop out truss extensions 12c, 12d when outer collar 11c is moved forward. Either arrangement would ease assembly and disengagement because operating two joints 11 simultaneously can be awkward for one person acting alone. 
     With reference now to FIGS. 7A-7D, water bike A&#39;s pedal driven paddle wheel propulsion system is shown. Axle means 60 comprises transverse axle 61 mounted to lower frame member 3a through sprocket shaft housing 62. Axle assembly 60 is coupled by sprockets 54a, 54b and chain 52 to pedals 56 (FIG. 4), similarly to a bicycle sprocket and chain mechanism. Pedals 56 are mounted by known means high on housing 20 near forward frame member 3d to position them nearly horizontally forward of seat 9. Such positioning of pedals 56 creates a recumbent pedaling position for driver D which is relaxing and comfortable to most drivers. Further, it allows driver D&#39;s center of gravity to be lower than if driver D were sitting upright. Sprockets 54a, 54b preferably have a one-to-one (1:1) ratio, but one having ordinary skill in the art will recognize that the ratio between sprockets 54a, 54b can provide driver D with some mechanical advantage, and that a multi-speed sprocket transmission system common to racing bicycles could be incorporated, without departing from the spirit and scope of the invention. 
     As detailed in FIG. 7B, nylon bushings 64 fit snugly into each end of sprocket shaft housing 62, and sprocket shaft 66 extends through bushings 64 and protrudes beyond both ends of shaft housing 62. Chain sprocket 54a mounts to one end of shaft 66, and shaft collar 68 retains shaft 66 in position. Shaft 66 comprises a cylinder having a uniform, circular outside diameter which rotates smoothly within bushings 64. The inside of shaft 66 comprises a non-circular cross section, for example hexagonal, and is adapted to receive internally axle 61 having a mating cross section. Thus, rotation of sprocket 54b with pedals 56 causes axle 61 to rotate with shaft 66. Suitable end fasteners 69 keep axle 61 from slipping out of place. 
     FIG. 7A further depicts in cross section two paddle wheel assemblies mounted onto axle 61, one on either side of shaft 66 and frame member 3a. A plurality of wooden, metal or plastic paddle blades 72, having narrow proximate ends adjacent axle 61 and broad distal ends, are disposed around the perimeter of axle 61 and held in place by hubs 74. Paddles 72 preferably are made of plastic, such as cross-linked polyethylene, for lightness, strength and ease of fabrication. NOTE: blades 72 appear in FIGS. 2 and 3, but various pairs thereof are omitted for clarity and simplicity. For example, in FIG. 2, horizontal blades 72 are shown, but vertical and diagonal blades are omitted. Likewise, in FIG. 3, vertical blades 72 are shown, but horizontal and diagonal blades are omitted. 
     Hubs 74 comprise circular disks of metal or plastic having apertures which receive internally and mate with the cross section of axle 61, thereby causing hubs 74 to rotate with axle 61. Radiating from axle 61 toward the outer circumference of hubs 74 are slots 76 adapted to receive tabs 78 disposed on the proximate ends of blades 72. When two hubs 74 are drawn together against the edge of paddle blades 72, tabs 78 lock into slots 76 and hold paddle blades 72 radial to axle 61, thereby causing them also to rotate with sprocket 54a. Tabs 78 and slots 76 are tapered slightly to tighten the fit between them. 
     Paddle blades 72 are selected to have a radial length extending downward from frame member 3a into the water beneath seat 9 as they rotate around axle 61 in a plane parallel to axis L. Paddles preferably are approximately ten and one-half (101/2&#34;) inches long (radial length) and one foot wide at their widest point (transverse axis L). When paddle wheel assembly 60 is mounted on frame 3, blades 72 extend to within two inches of the bottom of pontoons 8, so that water bike A may be placed on the ground or other hard surface without its weight resting on blades 72. As driver D rotates pedals 56, blades 72 push water parallel to axis L, causing thrust to water bike A and moving it along axis L. 
     Paddle wheel assembly 60 is mounted as shown in the figures to lower frame member 3a just forward of frame tie member 3c. One having ordinary skill in the art will recognize that it could be mounted at selected other places, including on an outrigger structure (not shown) behind truss 12, in a fashion similar to paddle wheels on a river boat. Obviously, such arrangement would add to the complexity, weight and cost of water bike A, but it is within the scope and spirit of the present invention. Mounting as shown in the figures balances the weight and thrust and permits driver D to mount water bike A from the rear as discussed above. 
     In operation, driver D sits in seat 9, places his feet on pedals 56 and grasps handle 24 by T-grip 1. If he wishes to travel forward, he rotates pedals 56 clockwise (as viewed in FIGS. 1 and 4), thereby causing paddle blades 72 also to rotate clockwise, pushing water rearward and thrusting water bike A forward. If driver D instead wishes to travel backward, he simply rotates pedals 56 counterclockwise. Because pedals 56 may rotate in either direction, they also serve as a braking system. If water bike A is traveling forward and driver D wishes to slow or stop progress, he simply rotates pedals 56 counterclockwise to create counter thrust, thereby adjusting his speed easily and precisely. 
     For transportation or storage, water bike A quickly and easily may be disassembled into eight components: three pontoons 8, 18, truss 12, frame 3, seat 9, an axle assembly (axle 61, hubs 74 and a stack of paddle blades 72) and handle 24. With water bike A still floating in the water or sitting on land, the user may release end fastener 69 and extract axle 61 along its axis transverse axis L from within hubs 74 and sprocket shaft 66, as shown in FIG. 7C. Hubs 74 then release paddle blades 72, which may be stacked compactly, and hubs 74 and axle 61 laid aside. Sprocket 54a remains attached to frame 3 through sprocket shaft 66, thereby retaining chain 52 on frame 3 as well. The user then may loosen knob 36, release end latch 10 and slide seat 9 off the rearward end of frame member 3d. Next, the user may release quick release locks 7 on pontoons 8, 18 and set pontoons 8, 18 aside. Finally, the user may compress spring 11b with outer collar 11a on quick release joints 11 and decouple frame 3 from truss 12. Frame 3 and truss 12 now are substantially planar and may be stacked together to save space. Handle 26 also may be decoupled from housing 20 if desired. Chain 52 may remain on sprockets 54a, 54b, which remain attached to frame 3. Assembly for use may be accomplished by reversing the foregoing steps. 
     Pontoon water bike A provides a light weight, easily portable, one-man raft which is inexpensive to obtain and operate because it comprises inexpensive materials and has no complex mechanisms or motors or fuel supplies. Water bike A includes highly stable steering and disassembles easily and quickly for compact transportation and storage. When disassembled, a water bike A fits conveniently into the trunk or back seat of a conventional automobile. 
     When constructed of steel tubing and plastic pontoons and paddle blades, water bike A weighs approximately seventy-five (75#) pounds. When pontoons 8, 18 each are twelve (12&#34;) in diameter and four (4&#39;) feet in length (approximately 3 cubic feet of captive air volume) and made of plastic, water bike A can support a human adult of average weight (175-190 lbs) while floating in as little as six inches of water. If additional cargo capacity or carrying a substantially heavier driver is required, additional pontoons or other flotation devices may be coupled to the outboard (opposite axis L) side of rear pontoons 8 by convenient means such as non-stretch straps. Adding two more rear pontoons 8 increases by two thirds the buoyancy and load capacity of water bike A. 
     While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention. For example, pontoons 8, 18 need not be identical, but could have differing shapes which might vary movement efficiency under different water conditions. Also, they could be of flexible plastic and deflatable for even more compactness during storage and transportation. Handle 24 could terminate in a single hilt (not shown) or other convenient grip rather than T-handle 1. Also, suitable storage capacity, such as saddlebags, could be mounted to truss 12, perhaps necessitating lugs thereon for stability. Truss means 12 further could comprise deck means in place of or in addition to truss member 12a. Said deck means (shown in one possible configuration in phantom in FIG. 2) could be planar, symmetric or asymmetric along its longitudinal dimension (parallel axis L) and could extend any convenient longitudinal length up to or even exceeding that of rear pontoons 8. Finally, other known primer mover means, such as electric or fuel driven motors mounted to frame 3 or truss 12 and coupled to sprocket shaft 62, could be provided in addition to or in lieu of human power, with obvious consequences of additional weight and cost.