Abstract:
A watercraft comprises a hull, and a propulsion system coupled to the hull. The propulsion system comprises at least two propulsion discs, at least two drive inputs, and a differential coupled to the drive inputs. Each drive input is coupled to a respective one of the propulsion discs. The differential includes a power control input and is configured to vary a delivery of power from the drive inputs to the propulsion discs in accordance with the power control input.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This patent application claims the benefit of the filing date of U.S. Patent Application Ser. No. 60/851,321, entitled “Turbo Boat”, filed Oct. 13, 2006, and U.S. Patent Application Ser. No. 60/851,322, entitled “Stingray Boat”, filed Oct. 13, 2006. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention described herein relates to a self-propelled watercraft. In particular, the invention relates to a pedal-powered watercraft. 
       BACKGROUND OF THE INVENTION 
       [0003]    Conventional pedal-powered watercraft are typically implemented as a kayak or a catamaran, and comprises a human-powered propulsion system. The propulsion system comprises a paddlewheel which is supported on a rotatable crankshaft. The crankshaft includes pedals which are disposed at opposite ends thereof, and requires both peddlers to pedal together at the same speed to move the watercraft. 
       SUMMARY OF THE INVENTION 
       [0004]    The invention relates to a watercraft propulsion system that is powered by independent drive input mechanisms. 
         [0005]    In accordance with one aspect of the invention, there is provided a propulsion system that comprises at least two propulsion discs, at least two drive inputs, and a differential coupled to the drive inputs. Each drive input is coupled to a respective one of the propulsion discs. The differential includes a power control input and is configured to vary a delivery of power from the drive inputs to the propulsion discs in accordance with the power control input. 
         [0006]    In accordance with another aspect of the invention, there is provided a watercraft that comprises a hull buoyant in water, and a propulsion system coupled to the hull for propelling the hull in the water. The propulsion system comprises at least two propulsion discs, at least two drive inputs, and a differential coupled to the drive inputs. Each drive input is coupled to a respective one of the propulsion discs. The differential includes a power control input and is configured to vary a delivery of power from the drive inputs to the propulsion discs in accordance with the power control input. 
         [0007]    In one implementation, the power control input comprises a control level, and the differential is configured to couple the drive inputs together when the power control lever is in a first position, and to uncouple the drive inputs from each other when the power control lever is in a second position. 
         [0008]    Further, each drive input comprises a pedal provided on a crankshaft, and the differential further comprises a drive key. The drive key is coupled to the power control lever and is movable between a lock position in which the crankshafts are coupled together when the power control lever is in the first position, and an unlock position in which the crankshafts are uncoupled from each other when the power control lever is in the second position. 
         [0009]    The differential may also comprise a plurality of crankshaft couplings, each coupled to a respective one of the crankshafts. Preferably, each crankshaft coupling comprises a key, and the drive key is configured to be received within the keys of the crankshafts when the power control lever is in the first position. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
           [0011]      FIG. 1  is a perspective view of the watercraft, according to the invention; 
           [0012]      FIG. 2  is a perspective view of the hull of the watercraft shown in  FIG. 1 ; 
           [0013]      FIG. 3  is a perspective view of the seats of the watercraft; 
           [0014]      FIG. 4  is a schematic view of the propulsion system of the watercraft; 
           [0015]      FIG. 5  is an exploded schematic view of the differential of the propulsion system; 
           [0016]      FIG. 6  is a magnified exploded view of the differential; 
           [0017]      FIG. 7  is a schematic view of the propulsion system with the propulsion discs locked together; and 
           [0018]      FIG. 8  is a schematic view of the propulsion system with the propulsion discs unlocked from each other. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0019]    As shown in  FIG. 1 , the watercraft, according to the invention, is hydrodynamically-stable, and comprises a plastic molded hull  1 , an inflatable seat  3  at the stern of the boat, a fabric hammock  4  at the bow of the boat, and a bimini assembly that is secured to the hull  1 . The boat also includes a shallow keel  23  that is integrally molded with the underside of the hull  1 . 
         [0020]    The bimini assembly includes a pair of support rods  15 , and a canopy  5  that is secured to the support rods  15 . 
         [0021]    The hull  1  is depicted in isolation in  FIG. 2 . As shown, the hull  1  is substantially flat, and includes a pair of anchor mounts  17  at the left-hand side and the right-hand side of the hull  1 , a pedestal mount  19  at the centre of the hull  1 , and a series of through-holes  18  at the bow for securing the hammock  4  to the hull  1 . The hull  1  also includes a pair of left-hand and right-hand bailing holes  21 , and a pair of wheel wells disposed on the left-hand side and the right-hand side of the hull  1 . Each wheel well is disposed in front of the respective bailing hole  21 , and houses a respective propulsion disc  2  ( FIG. 1 ). Each wheel well includes a vertical opening  16  in the side thereof for receiving one end of a respective crankshaft  6  ( FIGS. 1 and 4 ). 
         [0022]    The inflatable seat  3  is depicted in isolation in  FIG. 3 . As shown, the seat  3  include a pair of pivoting backrests  13 , and a pair of fixed backrests disposed rearwardly of the pivoting backrests  13 . Each pivoting backrest  13  includes a tether  24 , that is secured to the base of the seat  3  for restricting rearward movement of the backrests  13 . In addition, as shown in  FIG. 1 , the seat  3  include a pair of bimini mounts  11  at the opposite ends thereof for retaining an end of a respective bimini support rod  15 , and a pair of corresponding release levers  14  for releasing the support rods  15  from the bimini mounts  11 . 
         [0023]    As shown in  FIG. 1 , the boat includes a steering and drive column  9  that is mounted to the hull  1  at the pedestal mount  19 . The components of the steering and drive column  9  are best shown in  FIGS. 4 to 6 . As shown, the steering and drive column  9  comprises a release lever  32 , a pair of open ended or U-shaped crankshaft bearings  33 , a pedestal  30  supporting the release lever  32  and the crankshaft bearings  33 , and a pair of left-hand and right-hand pedestal cover members  28  that are secured to the top of the pedestal  30 . The steering and drive column  9  also comprises a pair of open-ended crankshaft couplings  34 , and a drive key  36  disposed between the crankshaft couplings  34 . 
         [0024]    Each crankshaft coupling  34  is supported by a respective one of the crankshaft bearings  33 . Each crankshaft coupling  34  is also keyed at one end thereof, and is secured at the opposite end to the inner end of a respective one of the crankshafts  6  via a fastener  37 . The outer (opposite) end of each crankshaft  6  is secured to a propulsion disc  2 , and is supported by a bearing assembly  8  proximate adjacent the propulsion disc  2 . The bearing assembly  8  is secured to the hull  1  at the vertical opening  16  of the hull  1 . 
         [0025]    The drive key  36  includes a continuous track disposed around its circumference, and a pair of laterally-extending keys that are configured to be slidably received within the keyed ends of the crankshaft couplings  34 . 
         [0026]    The release lever  32  includes a handle at one end thereof, a downwardly-extending guide pin  39  at the opposite end thereof, and a downwardly extending neck  38  between the handle and the guide pin  39 . The guide pin  39  is dimensioned to be received within the continuous track of the drive key  36 . 
         [0027]    The pedestal  30  includes a pair of U-channels each retaining one of the crankshaft bearings  33 . The pedestal  30  also includes a pivot hole  43  that is dimensioned to receive the neck  38  of the release lever  32  therein to thereby allow the release lever  32  to be pivoted about the pivot hole  43 . Preferably, the pedestal  30  also includes a pair of stops  40  for limiting the maximum angle of rotation of the release lever  30 , and a series of detents  42  disposed between the stops  40  for limiting the rotational movement of the release lever  32  about the pivot hole  43 . 
         [0028]    The pedestal cover members  28  enclose the crankshaft bearings  33 , crankshaft couplings  34 , drive key  36 , neck  38 , guide pin  39  when secured to the top of the pedestal  30 . As shown in  FIG. 5 , each pedestal cover member  28  includes an upper bearing that engages the crankshaft couplings  34 , opposite the crankshaft bearings  33 , and serves to retain the crankshaft couplings  34  within the crankshaft bearings  33 . Further, each pedestal cover member  28  includes a through hole  27  at the nose  25  thereof for receiving a cross-bar  10  therethrough. The cross-bar  10  includes a pair of anchors  26  at the opposite ends thereof. The anchors  26  are secured to the hull  1  at the anchor mounts  17 , thereby stabilizing the steering and drive column  9  via the cross-bar  10 . 
         [0029]    As shown in  FIG. 7 , if the release lever  32  is oriented in the centre position (relative to the stops  40 ), the drive key  36  is received within the left-hand and the right-hand crankshaft couplings  34 , thereby locking the left-hand crankshaft  6  to the right-hand crankshaft  6 . As a result, pedaling of the crankshafts  6 , via the pedals  7 , rotates the left-hand propulsion disc  2  at the same speed as the right-hand propulsion disc  2 , thereby causing the boat to move straight forwards or backwards. 
         [0030]    However, as shown in  FIG. 8 , if the release lever  32  is rotated to the left or right of centre, the guide pin  39  shifts the drive key  36  to the left or to the right (depending upon the direction of rotation of the release lever  32 ), thereby releasing the drive key  36  from the left-hand or the right-hand crankshaft coupling  34 . In this mode the left-hand crankshaft  6  becomes unlocked from the right-hand crankshaft  6 . As a result, the occupants can steer the boat to the left or right simply by changing the relative speed or direction of rotation of the crankshafts  6 .