Patent Publication Number: US-6210242-B1

Title: Pedal-powered watercraft

Description:
CROSS-REFERENCE TO RELATED PATENTS 
     This application is related to U.S. Pat. No. Des. 399,814, issued on Oct. 20, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to watercraft, and more particularly to occupant-powered watercraft. 
     2. Description of the Related Art 
     The popularity of pedal-type watercraft has increased in recent years, due at least in part to individuals who are both health-conscious and concerned for their personal safety on the roadways. Bicycling, although quite popular, is high on the list of most dangerous activities. With increased congestion on roadways and its accompanying hazards, many cyclists have turned to the waterways where the workout of a bike ride is combined with wide open spaces and its accompanying scenery. Moreover, recent laws banning motorized personal watercraft due to environmental concerns have also contributed to the increasing popularity of pedal-powered watercraft. 
     One type of pedal-powered watercraft is disclosed in U.S. Pat. No. 4,795,381 issued to Willems on Jan. 3, 1989. The watercraft in this patent includes a floating body upon which a pedal assembly and recumbent seat are mounted. The seat can be adjusted toward or away from the pedal assembly to accommodate different sizes of users. An endless drive chain, reduction gearing, and a drive shaft connect the pedal assembly to a propeller. In one embodiment of this patent, the propeller and drive shaft extend downwardly and rearwardly from the floating body. A tandem seating arrangement is also shown. 
     Another type of pedal-powered watercraft is disclosed in U.S. Pat. No. 5,460,551 issued to Beres on Oct. 24, 1995. In this patent, the pedal-powered watercraft is shaped as a kayak with an integrally molded seat. A pedal assembly is connected to a propeller through a transmission and drive shaft arrangement. A front storage compartment as well as a rear storage compartment are provided. 
     Pedal-powered watercraft similar to the above types have hulls that are inherently unstable in the water. Great skill is required to keep the vessel from capsizing, especially during mounting, dismounting, pedaling, and turning operations. Many potential users, especially those that pursue recreation only occasionally or those that lack confidence in the water, may thus be apprehensive about using such watercraft. 
     Prior art pedal-powered watercraft also suffer in their inefficiency to translate rotational motion of the pedals into watercraft speed. Many users find that their legs become tired before completing the time interval needed for an ideal cardiovascular workout, while the distance traveled is somewhat less than exhilarating. Increasing the rotational speed of the pedals often does little toward increasing the speed of watercraft movement. As an example, typical pedal-powered watercraft having a pair of side-by-side pedal assemblies only travels approximately 1-2 mph in the water, despite increased rotational speed of the pedals. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a pedal-powered watercraft that overcomes the problems associated with the prior art. 
     It is a further object of the invention to provide a pedal-powered watercraft that is relatively stable in the water. 
     It is an even further object of the invention to provide a pedal-powered watercraft that has improved efficiency of occupant effort to watercraft velocity. 
     According to the invention, an occupant-powered watercraft comprises a unitary hull having an upper wall extending from a bow portion to a stern portion of the watercraft with a pair of spaced hollow sponsons located on either side of the upper wall. Each sponson extends along the length of the hull and has an inner wall connected to an outer wall by a bottom wall and front and rear walls to thereby form a hollow interior. The inner walls of the sponsons are integrally joined to opposite sides of the upper wall. The upper wall together with the inner walls of the sponsons form a tunnel that opens generally downwardly and extends from the bow portion to the stern portion of the watercraft. A deck is connected to the hull and includes elongate opening that defines a cockpit area for receiving an occupant. A seat is located in the cockpit area and a pedal assembly is connected to the hull forwardly of the seat. The pedal assembly includes a pair of rotatable pedals. A propeller is operably connected to the pair of pedals for rotation of the propeller in response to rotation of the pedals. With this arrangement, forward movement of the watercraft from rotation of the propeller causes water to enter into the tunnel at the bow portion and exit the tunnel at the stern portion. 
     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. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The preferred embodiments of the present invention will hereinafter be described in conjunction with the appended drawings, wherein like designations denote like elements, and wherein: 
     FIG. 1 is a perspective view of a pedal-powered watercraft according to the invention; 
     FIG. 2 is a front elevational view of the pedal-powered watercraft of FIG. 1; 
     FIG. 3 is an exploded isometric view of the pedal-powered watercraft of FIG. 1; 
     FIG. 3A is an enlarged exploded isometric view of the pedal assembly of FIG. 3; 
     FIG. 3B is an enlarged exploded isometric view of the transmission assembly of FIG. 3; 
     FIG. 3C is an enlarged exploded isometric view of the steering assembly of FIG. 3; 
     FIG. 4 is an an enlarged view of the seat, pedal and transmission assemblies of the pedal-powered powered watercraft in a substantially assembled form; 
     FIG. 5 is an isometric view of the watercraft hull with the seat, pedal and transmission assemblies well as a portion of the steering assembly attached to the hull; 
     FIG. 6 is an enlarged cross sectional view of the hull and illustrating the connection between the hull and transmission mechanism; 
     FIG. 7 is a longitudinal cross sectional view of the hull with an installed drive shaft and propeller; 
     FIG. 8 is a longitudinal cross sectional view of the hull according to a further embodiment of the invention with an installed drive shaft and propeller; 
     FIG. 9 is a top plan view of a pedal-powered watercraft according to a further embodiment of the invention; 
     FIG. 10 is a side elevational view of a tandem pedal-powered watercraft according to an even further embodiment of the invention; 
     FIG. 11 is a side elevational view of a transmission and tandem pedal assemblies; 
     FIG. 12 is a top plan view of the transmission and tandem pedal assemblies of FIG. 
     FIG. 13 is a top plan view of a transmission and tandem pedal assemblies according to a further embodiment of the invention; 
     FIG. 14 is a top plan view of a power-assist assembly for use with any of the previous embodiments; 
     FIG. 15 is a side elevational view of a tandem pedal-powered watercraft similar to FIG. 10 with an installed wing sail; 
     FIG. 16 is a perspective view of a pedal-powered watercraft similar to FIG. 1 with an installed law sail; 
     FIG. 17 is a longitudinal cross sectional view of a hull with an installed modular locomotion assembly according to a further embodiment of the invention; 
     FIG. 18 is a view similar to FIG. 17 with the locomotion assembly in a retracted condition; 
     FIG. 19 is a rear elevational view of the modular assembly with a portion of the hull in cross section; and 
     FIG. 20 is an enlarged cross sectional view of a hull with an installed modular locomotion assembly according to an even further embodiment of the invention. 
    
    
     It is noted that the drawings of the invention are not necessarily to scale. The drawings are merely schematic representations, not intended to portray specific parameters of the invention. The drawings are intended to depict only typical embodiments of the invention, and therefore should not be considered as limiting the scope of the invention. The invention will now be described with additional specificity and detail through the accompanying drawings. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, and to FIGS. 1 to  3  in particular, a pedal-powered watercraft  10  according to the invention is illustrated. The watercraft  10  includes a hull  12 , a deck  14 , a locomotive assembly  16 , and a steering assembly  18 , all preferably connected to the hull  12 . 
     The hull  12  is preferably formed as a unitary structure and includes a pair of hollow sponsons  20  that extend the length of the hull. Each sponson  20  includes an outer wall  22  and inner wall  26  that curve generally outwardly with respect to a longitudinal centerline of the hull, a bottom wall  24  that extends between the inner and outer walls and curves generally downwardly, a front wall  28  that extends upwardly from a forward portion of the bottom wall and between the inner and outer walls, and a rear wall  30  that extends upwardly from a rearward portion of the bottom wall and between the inner and outer walls. 
     The inner walls  26  of the sponsons  20  converge with an upper wall  31  that together form a tunnel  32  that extends the length of the hull. The upper wall  31  of the tunnel  32  includes an upper surface  33  and a lower surface  35  (see FIG.  7 ). In this embodiment, the tunnel  32  is preferably semi-cylindrical and substantially uniform in shape throughout its length, with the exception of a protrusion  34  that extends downwardly into the tunnel  32  to accommodate a transmission assembly  86  that forms part of the locomotion assembly  16 . The protrusion  34  includes a lower wall  36  that slopes generally downwardly and rearwardly toward the stern of the hull  12 , and an upright wall  37  that extends generally upwardly from the lower wall  36 . An opening  39  is formed in the wall  37  for a purpose to be described in greater detail below with respect to FIG.  6 . The particular advantages of the tunnel  32  will be described in further detail below in conjunction with the locomotion assembly  16 . 
     The front wall  28  of each sponson  20  curves generally downwardly and forwardly to reduce drag and provide lift to the bow during forward movement of the watercraft  10  through water. The rear wall  30  of each sponson curves generally downwardly and rearwardly to advantageously provide greater maneuverability in the water during turning than would otherwise be possible without the curve. This is due at least in part to the reduction of surface area in contact with the water during turning, and thus the reduction of forces inhibiting turning. 
     As shown most clearly in FIG. 3, a ledge  40  is formed around the top periphery of the hull  12 . A curved section  42  separates rearwardly extending portions of the sponsons  20  at the stern of the watercraft  10 , while a web section  44  joins the sponsons at the bow. The web section  44  helps to shield an operator from overspray or splashing, especially during travel in rough water. 
     With additional reference to FIG. 5, a pair of front inserts  46  are mounted in the bow of the hull  12  while a pair of rear inserts  48  are mounted in the stern. Each insert  46 ,  48  includes a generally horizontally extending wall  50  and a generally vertically extending wall  52  that depends from the wall  50 . The edges of each insert  46 ,  48  are shaped to fit snugly against the inner wall  26 , the outer wall  22 , the bottom wall  24 , and the front or rear wall  28  or  30  of its respective sponson to thereby form four air-tight compartments. Preferably, an opening  54  is formed in each wall  52  in order to permit access into the compartments for storing equipment and supplies. The openings are preferably sealed by a removable cap (not shown) in order to maintain the air-tight integrity of the compartments. 
     Referring again to FIGS. 1 to  3 , the deck  14  is preferably of single piece construction and includes an upper wall  60  that curves generally downwardly toward the bow and stern portions of the deck from a cowling  66 . A pair of side walls  62  also extend generally downwardly toward the port and starboard sides of the deck from the upper wall. An oblong opening  64  is formed in the deck  14 . The cowling  66  is formed integrally with the upper wall  60  and side walls  62  and surrounds the opening  64 . The opening  64  in the deck  14  provides access to a hollow interior space or cockpit  68  located between the hull  12  and deck  14 . An inwardly curved section  78  at the stern portion of the deck matches the curved section  42  at the stern portion of the hull  12 . A lower peripheral edge  70  of the deck  14  terminates in an L-shaped flange  72 . The flange  72  has a first leg  74  that extends generally horizontally and a second leg  76  that extends downwardly from the first leg  74 . When the deck is assembled to the hull, the first leg  74  of the deck and the ledge  40  are superimposed, and the second leg  76  extends downwardly past the ledge  40 . With this arrangement, the fingers of a user can securely grip the ledge  40  and second leg  76  during handling, e.g. during lifting and carrying, of the watercraft  10 . 
     The hull and deck are preferably constructed of a strong, light-weight and waterproof material, such as fiberglass, aluminum, composites, laminates, and the like. A multi-layer laminate known as Royalex™ is especially suitable for the hull and deck. This type of laminate comprises one or more core layers of foam material sandwiched between layers of ABS plastic which are in turn sandwiched between layers of vinyl. The foam layers contribute to increased buoyancy, the ABS layers add strength, durability and rigidity, and the vinyl layers provide a wear-resistant and waterproof barrier to the inner layers, as well as an aesthetically pleasing finish. Preferably, the hull  12  and deck  14  are joined at the ledge  40  and horizontal leg  74  through a suitable adhesive for the particular material selected. Alternatively, the hull and deck may be joined through ultrasonic welding, mechanical fastening, or other well-known joining means. 
     Turning now to FIGS. 3 to  5 , the locomotion assembly  16  comprises a base frame  80  mounted to the hull  12 , a pedal assembly  82  connected to the base frame, a transmission assembly  86  connected to the base frame proximal the pedal assembly, and an adjustable seat assembly  88  connected to the base frame rearwardly of the pedal assembly  82 . 
     As best shown in FIGS. 3B and 4, the base frame  80  is generally C-shaped in cross section and is preferably constructed of a lightweight and relatively rigid material, such as aluminum. The base frame  80  includes an upper platform  90  from which a pair of legs  92  and  94  depend. A flange  96  is formed at the lower free end of each leg  92 ,  94  and is shaped to contact an upper surface of the walls  26  that form the tunnel  34 . The base frame  80  is mounted to the hull  12  by bonding the flanges  96  to the upper surface of the walls  26  with a suitable adhesive. Alternatively, the base frame  80  may be mounted to the hull through mechanical fasteners or a combination of adhesive and fasteners. An opening  98  (FIG. 3B) is formed in the platform  90  at a forward portion thereof and an aperture  99  is formed in each leg  92 ,  94  below the opening  98 . 
     As best shown in FIG. 3A, the pedal assembly  82  includes a pedal tower  100  having a lower tower section  102  fixedly connected to an upper tower section  104  through suitable fasteners (not shown) that extend through elongate openings  105  in the lower section  102  and aligned apertures  107  in the upper section  104 . The lower section  102  includes an inverse U-shaped mounting bracket  106  having a pair of spaced legs  108 ,  110  that straddle the base frame  80  such that the legs  108  and  110  are adjacent the legs  92  and  94 , respectively. Each of the legs  108 ,  110  includes an aperture  112  that is in alignment with the apertures  99  of the base frame  80 . A fastener (not shown) extends through each of the pairs of aligned apertures  112 ,  99  and pivotally connects the pedal tower  100  to the base frame  80 . 
     The upper tower section  104  includes a bearing block  120  with a central bore  122  that rotatably receives an axle  124 . The axle  124  is fixedly connected to an upper sprocket wheel  126 . A pair of pedal arms  128  are in turn fixedly connected to the axle  124 , and a foot pedal  130  is rotatably connected to a free end of each pedal arm  128  in a well-known manner. 
     A strut  140  is pivotally connected between the pedal tower  100  and the base frame  80  for selectively adjusting the pedals  130  with respect to the seat assembly  88 . The strut  140  includes a tubular member  142  that telescopically receives a rod  144 . A locking lever  146  is connected to the tubular member  142  for selectively fixing the position of the rod  144  with respect to the tubular member. Preferably, the tubular member  142  has an inner diameter that is slightly greater than the outer diameter of the rod  144  to allow free linear movement of the rod with respect to the tubular member when the locking lever is released. A gap (not shown) can be formed in the tubular member adjacent the exit point of the rod  144 . Closure of the gap by the locking member causes the tubular member to press against and hold the rod  144  against movement. As an alternative to a locking lever, a spring-loaded push-button (not shown) may be mounted on the rod  144  and a series of apertures (not shown) may be formed in the tubular member  142  such that engagement of the push-button with one of the apertures prevents further telescopic movement of the rod with respect to the tubular member in a well-known manner. Other well-known means for fixedly adjusting the length of the strut  140  are also contemplated. 
     The outer end  148  of the tubular member  142  is pivotally mounted to a U-shaped bracket  150  located on the platform  90 . Likewise, the outer end  152  of the rod  144  is pivotally mounted to a U-shaped bracket  154  located on the upper tower section  104 . In this manner, the pedal tower  100  along with the pedals  130  can be tilted toward and away from the seat assembly  88  to thereby accommodate the size and personal preferences of a user. 
     As best shown in FIG. 3B, the transmission assembly  86  includes a transmission  160  having an input shaft  162  and an output shaft  163  that extends substantially perpendicular to the input shaft. The output shaft is connected to the input shaft through a bevel gear arrangement (not shown) within the transmission  160  such that for every revolution of the input shaft, the output shaft has a corresponding revolution. A lower sprocket wheel  164  is mounted on the input shaft  162  for rotation therewith and an endless drive chain  166  (FIG. 5) extends between the upper sprocket wheel  126  and the lower sprocket wheel  164 . Preferably, the rotational axis of the input shaft  162  and the lower sprocket wheel  164  is coincident with the rotational axis of the pedal tower  100 . In this manner, the chain  166  will remain taut when the pedal tower is pivoted. The upper sprocket wheel preferably has a greater number of teeth than the lower sprocket wheel. Preferably, the ratio between the upper sprocket wheel and the lower sprocket wheel is approximately 6:1 such that every revolution of the upper sprocket wheel causes six revolutions of the output shaft. Of course, other ratios can be chosen depending on varying factors such as the watercraft size, weight, user weight and strength, the desired cruising speed, and so on. When it is desirous to install, replace or tighten the chain  166 , the fasteners (not shown) extending through the openings  105 ,  107  of the pedal tower are loosened and the upper tower section  104  is slid upwardly or downwardly with respect to the lower tower section  102  until the appropriate adjustments have been made and the chain is taut. The fasteners are then tightened. 
     With additional reference to FIG. 6, the transmission  160  is connected to the base frame  80  via a transmission mounting bracket  168 . The mounting bracket  168  includes a transmission mounting plate  170  extending between a front flange  172  and a rear flange  174 . The flanges  172 ,  174  lie flat against the upper surface of the platform  90  while the mounting plate  170  slopes generally downwardly and rearwardly from the front flange  172  toward the rear flange  174 . A plurality of fasteners (not shown) extend through elongate apertures  176  formed in the plate  170  and flanges  172 ,  174  for mounting the transmission  160  to the plate  170  and the bracket  168  to the platform  90 , respectively. With this arrangement, the output shaft  163  of the transmission  160  extends downwardly and rearwardly through the opening  39  in the wall  37  of the hull at the same slope as the plate  170 . 
     A bearing sleeve  180  has a head  182  that receives an O-ring (not shown) and rests against an inner surface of the wall  37  and a threaded shaft  184  that extends through the opening  39 . An O-ring  186  and threaded nut  188  are received onto the bearing sleeve  180  and press against the outer surface of the wall  37  to form a water-tight seal. Preferably, the bearing sleeve is constructed of a waterproof or water-resistant material that also exhibits a low coefficient of friction, such as nylon, brass, or the like. The output shaft  163  extends through the bearing sleeve  180  and rotates freely with respect thereto. The output shaft  163  also preferably forms a waterproof seal with the bearing sleeve  180  through one or more additional O-rings (not shown) mounted between the output shaft and bearing sleeve, or through any other well known shaft sealing means. With this construction, the transmission  160  is secured to the hull  12  at two separate locations, i.e. on the base frame  80  and the wall  37  to thereby reduce torsional and/or other forces that may be acting on the transmission during use. 
     With additional reference to FIG. 7, a drive shaft  190  has a first end  192  that is coupled to the output shaft  163  for rotation therewith and a second end  194  that has a propeller  196  mounted thereto. Preferably, the outer end of the output shaft  163  and the first end  192  of the drive shaft  190  are received in an elastomeric bushing  198  that frictionally couples the shafts together such that rotation of the output shaft causes rotation of the drive shaft. The elastomeric bushing also serves to correct for minor misalignment between the output shaft and the drive shaft and to at least partially isolate the transmission when the propeller becomes stuck due to entanglement with underwater weeds or the like to thereby prevent damage to the propeller when a user continues to operate the pedal assembly. Alternatively, a rigid sleeve with appropriate fasteners or other connection means may be provided for coupling the output shaft to the drive shaft. The drive shaft  190  preferably extends downwardly and rearwardly from the bushing with the same slope as the output shaft  163 . Accordingly, the rotational axis of the drive shaft  190  is coincident with the rotational axis of the output shaft  163 . 
     A skeg  200  for supporting the drive shaft  190  includes a blade-like member  202  extending downwardly from a curved flange  204 . The flange  204  is mounted to the lower surface  35  of the upper wall  31  through adhesive, fasteners, or the like. When fasteners are used, it is preferable that a plate (not shown) be located on the upper surface  33  to sandwich the upper wall between the flange  204  and the plate. A bearing sleeve  206  constructed of nylon, brass, or the like intersects the blade-like member  202  and rotatably receives the drive shaft  190 . 
     Referring again to FIGS. 3,  4  and  5 , the adjustable seat assembly  88  includes a pair of rails  208  fixedly mounted to the platform  90  adjacent the legs  92  and  94 . A seat  210  is pivotally mounted on a sliding adjustment plate  216  which is in turn mounted for selective sliding movement on the pair of rails  208 . The seat  210  includes a lower body support  212  and a back support  214 . Preferably, the seat  210  is constructed as a single, unitary structure. A pair of lower mounting tabs  218  (only one shown in FIG. 3) extend downwardly from a forward portion of the lower body support  212 . Each mounting tab has an aperture that aligns with an aperture in the sliding plate  216 . A fastener (not shown) extends through each set of aligned apertures for pivotally mounting the forward end of the seat  210  to the adjustment plate. A pair of upper mounting tabs  224  (only one shown in FIG. 3) extend rearwardly from the back support  214 . A pair of adjustable support arms  220  extend between the back support  214  and the sliding plate  216 . Each support arm  220  includes an upper arm portion  222  that is pivotally connected to one of the upper mounting tabs  224 , and a lower arm portion  226  that telescopically receives the upper arm portion  226 . The lower arm portion  226  is in turn pivotally connected to the sliding plate  216 . A plurality of apertures  228  are formed in the upper arm portion and a knob  230  extends through the lower arm portion for selectively engaging one of the apertures. Preferably, the knob threadably engages the apertures, but may be biased toward the apertures in a well-known manner. With this arrangement, the tilt of the seat  210  can be adjusted by disengaging the knob  230  from one of the apertures  228 , rotating the seat forwardly or rearwardly until the desired amount of tilt is obtained, and engaging the knob  230  with another of the apertures  228 . 
     A pair of extension bars  232  are mounted to, and extend forwardly from the sliding plate  216 . A spring-loaded locking knob  234  is mounted on each extension bar and is adapted to engage one of the apertures  236  formed in the rail  208 . Adjustment of the distance between the seat  210  and the pedal assembly  82  is accomplished by pulling upwardly on the knobs  234  to disengage the knobs from their respective apertures, sliding the seat either forwardly or rearwardly until the desired distance is achieved, then seating each knob in another of the apertures. 
     As shown best in FIG. 3C, the steering assembly  18  comprises a steering control arm  240  rotatably connected to an inner wall  242  (FIG. 3) of the cowling  66 . The steering arm  240  is fixedly connected to a shaft  250  of a lever arm  248 . A washer  244  and a nut  246  are positioned on the shaft  250  and sandwich the wall  242  therebetween. The lever arm  248  is pivotally connected to a front linkage  252  of a sheathed cable  254 . A rear linkage  256  of the sheathed cable  254  is in turn pivotally connected to a tiller  258  with the sheathed portion of the cable being fixedly connected to an arm  260  of a rudder mounting bracket  262 . The rudder mounting bracket has a curved base  264  that mounts to the upper surface  33  of the tunnel  32  through adhesive, fasteners or the like, and a sleeve  266  extends upwardly from the base  264 . The sleeve  266  rotatably receives a shaft  268  of a rudder pivot bracket  270 . A pair of spaced arms  272  form part of the rudder pivot bracket  270  and are mounted on opposite sides of the shaft  268 . A rudder  274  has an upper end  278  that is sandwiched between a pair of nylon washers  276  or the like. The rudder upper end  278  together with the washers  276  are received within the spaced arms. Preferably, the rudder is pivotally connected to the arms  272  so as to rotate upwardly when encountering foreign objects during use. In this manner, the rudder  274 , the rudder mounting bracket  262 , the rudder pivot bracket  270 , as well as the hull  12  are less prone to damage. The rudder  274  and pivot bracket  270  are shown extending in a forward direction in FIG. 3 for clarity. In actual use, the rudder and post would extend in the opposite direction. 
     In use, upon entering the watercraft  10 , a user may find it necessary to adjust the seat inclination and position as well as the location of the pedals by tilting the pedal tower to a comfortable position, as previously described. As the user reclines in the seat and uses the pedals  130  to rotate the upper sprocket wheel  126 , the chain  166  forces rotation of the lower sprocket wheel  164 , which in turn causes the propeller  196  to rotate through the transmission  160  at a higher rotational velocity than the lower sprocket wheel to thereby propel the watercraft  10  through the water. The tunnel  32  forms a half-vortex which channels water toward the propeller during forward movement of the watercraft while at least partially blocking side currents that may be present. The tunnel hull helps to stabilize the watercraft during use and reduce the amount of surface area in contact with the water over conventional hulls and thus the amount of drag. Consequently, the watercraft can be operated at increased speeds with less pedal effort. In addition, the angle of the propeller  196  with respect to the hull  12  causes the watercraft  10  to lift slightly out of the water, which further reduces the surface area in contact with the water and its associated drag. The angle of the propeller can vary in the range of about 0 to about 45 degrees with respect to horizontal, and preferably is angled at about 8 degrees with respect to horizontal. Thus, the angle of the propeller  96  together with the tunnel  32  of the hull  12  create a pedal effort to watercraft speed efficiency that greatly exceeds the prior art. During trials of the above-described invention, it was found that a cruising speed of about 7 mph could be achieved and maintained with minimal effort from a person of average size and strength. Speeds of greater than 10 mph have been achieved with greater effort. 
     Although not shown, more than one lower sprocket wheel and/or upper sprocket wheel can be provided along with a derailleur or other gear adjusting mechanism for changing the gear ratio between the upper and lower sprocket wheels, and thus the rate of rotation between the upper wheel and the propeller. 
     With reference now to FIG. 8, a longitudinal cross section of a hull  280  according to a further embodiment of the invention is illustrated, wherein like parts in the previous embodiment are represented by like numerals. The hull  280  is similar in construction to the hull  12  previously described, with the exception that an upper wall section  282  of the tunnel  32  slopes generally downwardly and rearwardly from the bow to a plane defined by propeller rotation, and an upper wall section  284  that slopes generally upwardly from the wall section  282  toward the stern. With this construction, the possibility of air pockets in the propeller area is substantially reduced or eliminated since the entire propeller  196  is kept below the waterline  286  during use, even when the watercraft is subject to unequal loading between the bow and stern. Consequently, the watercraft is able to travel more efficiently in the water. 
     Turning now to FIG. 9, a top plan view of a watercraft  290  according to a further embodiment of the invention is illustrated, wherein like parts in the previous embodiments are represented by like numerals. The watercraft  290  includes a deck  292  with relatively flat upper wall sections  294  and  296  formed at the bow and stern, respectively, of the watercraft. The upper wall section  294  preferably extends between the bow end  298  of the deck  292  and the front of the cowling  66  that surrounds the cockpit  68 . Likewise, the upper wall section  296  preferably extends between the stern end  300  of the deck and the rear of the cowling  66 , and encompasses the curved section  78 . The upper wall section  296  together with the curved section  78  makes it easier for a person to climb into the watercraft from the water. A plurality of ribs  302  are preferably integrally formed on the upper wall sections  294 ,  296  for increased strength and rigidity. As shown, the ribs extend between the port and starboard sides of the deck  292  and may be of varying length. Although the ribs are preferably integrally formed, it is to be understood that the ribs may be formed separately and mounted to the upper wall sections. Hardware (not shown) may be connected to one or both of the upper wall sections for securing gear or the like thereto. 
     A deck plate  304  is removably attached to the upper wall section  296  and covers a tube (not shown) that extends through the deck  292  and hull  280  (or hull  12 ) directly above the propeller  196 . When the cap  304  is removed, a user&#39;s hand and arm can be extended through the tube for removing underwater plants or other foreign matter from the propeller  196  in the event that the propeller becomes entangled. In this manner, it is unnecessary for the user to leave the watercraft to access the propeller. 
     A seat  306  is preferably integrally formed with the deck  292  behind the seat  210  to accommodate a passenger, equipment, or the like. Preferably, the opening  64  in the deck  292  gradually increases in width from the bow to the stern. 
     With reference now to FIGS. 10 to  12 , a watercraft  310  according to a further embodiment of the invention is illustrated, wherein like parts in the previous embodiments are represented by like numerals. The watercraft  310  includes a front reclining seat  210  with a front pedal assembly  312 , and a rear reclining seat  314  with a rear pedal assembly  316 . Preferably, the front and rear reclining seats  210 ,  314  are similar in construction to the seat  210  previously described. 
     Each pedal assembly  312 ,  316  includes an upper sprocket wheel  126  rotatably connected to an upper end of a pedal tower  100 , a lower sprocket wheel  164  rotatably connected to the base frame  80 , and an endless drive chain  166  that extends around the upper and lower sprocket wheels. An axle  318  extends between, and is rotatably mounted to a pair of flanged bearing blocks  320  located on the legs  92  and  94  of the base frame  80 . The axle  318  is preferably constructed of a stainless steel material and is keyed or otherwise connected to the lower sprocket wheel  164  for rotation therewith. A freewheel sprocket  322  is connected to the axle  318  for rotation therewith only when the axle is rotated by the lower sprocket wheel  164 , and is disconnected from the axle when the lower sprocket wheel  164  is idle. An endless drive chain  324  extends between each freewheel sprocket  322  and a double sprocket wheel  326  keyed or otherwise connected to the input shaft  162  of the transmission  160 . Each of the flanged bearing blocks  320  includes fasteners  328  that can be loosened in order to move the bearing block along its associated leg  92 ,  94  for adjusting the tension of the drive chains  324 . Guide blocks  330 , constructed of nylon or the like, are mounted to the leg  94  for keeping the drive chains  324  in alignment with their associated sprocket wheels. 
     With the above-described tandem pedal assembly arrangement, either or both of the front and rear pedal assemblies can be operated to transfer rotational motion from the upper sprocket wheel(s) to the transmission  160  and drive shaft  190  independent of the other pedal assembly. When only one person is operating either the front or rear pedal assembly, the freewheel sprocket of the other pedal assembly will rotate without rotating the axle  318  to which it is mounted. In this manner, the pedals that aren&#39;t in operation remain stationary. 
     Turning now to FIG. 13, a top plan view of a tandem pedal assembly  340  according to a further embodiment of the invention is illustrated, wherein like parts in the previous embodiment are represented by like numerals. The tandem pedal assembly  340  includes front and rear pedal assemblies  342 ,  344  that are similar in construction to the front and rear pedal assemblies of the previous embodiment, with the exception that the axle  318  is fixedly mounted to the legs  92 ,  94  of the base frame  80 , and the lower sprocket wheel  164  and freewheel sprocket  322  are bolted or otherwise mounted together for mutual rotation around the axle  318 . The axle  318  is preferably constructed of a solid ceramic material and is held stationary by a pair of axle mounting brackets  346  that are rigidly connected to opposite ends of the axle  318  and adjustably connected to the legs  92 ,  94  of the base frame  80 . Preferably, both the freewheel sprocket  322  and the sprocket wheel  164  turn on a tubular Teflon™ bearing (not shown) held in place on the axle  318  between a spacer  348  and a shaft collar  350 . With this arrangement, the four bearing blocks of the previous embodiment are eliminated, resulting in cost savings while maintaining the independent operability of each pedal assembly. 
     With reference now to FIG. 14, a top plan view of a motor assist unit  360  for use in conjunction with one or more of the previously described pedal assemblies is illustrated, wherein like parts in the previous embodiments are represented by like numerals. The motor assist unit  360  includes a transmission  160  having a first input shaft  162  connected to a first lower sprocket wheel  164  and a second input shaft  362  connected to a second lower sprocket freewheel  364 . An electric motor  366  is connected to the base frame  80 . The motor  366  includes a shaft  368  and a sprocket wheel  370  fixedly connected to the shaft for rotation therewith. An endless drive chain  372  extends between the second sprocket wheel  364  and the motor sprocket wheel  370 . A battery  374  is electrically connected to the motor. Preferably, switching means  376  in the form of a torque sensor, a contact switch, or the like, is connected between the battery  374  and the motor  366  for selective actuation of the motor during operation of the watercraft. When a torque sensor is used, the motor  366  will be automatically actuated when the pedal force reaches a predetermined level to thereby assist or replace operator pedaling. When a contact switch is used, it is preferably manually manipulated by a user in order to actuate the motor at the user&#39;s discretion. 
     Turning now to FIG. 15, a pedal-powered watercraft  380  is illustrated, wherein like parts in the previous embodiments are represented by like numerals. The watercraft  380  is similar in construction to the watercraft  310  previously described, with the addition of a wing sail  382  pivotally connected to the hull ( 12  or  280 ) and deck ( 14  or  290 ) rearwardly of the cockpit  68  and midway between the port and starboard sides of the hull. The wing sail  382  is relatively stiff in construction and includes a mast  384  and a blade-like sail portion  386  extending rearwardly of the mast. Rotation of the sail  382  about the mast  384  can be controlled by a steering assembly (not shown) similar to the steering assembly  18  for the rudder  274  previously described. Preferably, the sail is removable for facilitating storage and transportation. 
     With reference now to FIG. 16, a pedal-powered watercraft  400  is illustrated, wherein like parts in the previous embodiments are represented by like numerals. The watercraft  400  is similar in construction to the watercraft  10  previously described, with the addition of a crab-claw sail  402  mounted forwardly of the cockpit  68  midway between the port and starboard sides of the hull ( 12  or  280 ) and deck ( 14  or  290 ). The crab-claw sail  402  includes a mast  404  that extends upwardly from the deck and a sail frame  406  pivotally connected to the mast. The frame  406  includes a longitudinally extending center support rod  408  that is pivotally connected to an upper end of the mast  404  and laterally extending support rods  410  that are pivotally connected at inner pivot joints  414  to the center support rod. The outer ends of the support rods  410  are in turn pivotally connected to outer support rods  412  at outer pivot joints  416 . Preferably, the inner and outer pivot joints  414 ,  416  are releasably lockable so that the sail  402  can be folded during transportation and storage and locked into position during use. A rear cable  418  extends from an outer pivot joint  416  to the deck while a front cable  420  extends from a forward position  422  of the sail to the deck for controlling rotation of the sail around the mast  404 . Preferably, the free ends of the cable are adjacent the cockpit  68  at a position convenient to a user. If desired, the cable ends can be terminated with a lever arm (not shown) or other mechanism for manipulating the sail. The crab-claw sail of the present invention provides both forward movement and lift to the watercraft. The lifting action of the sail lowers the waterline on the hull and therefore further reduces drag on the watercraft. 
     Turning now to FIGS. 17 to  19 , a hull  450  with an installed locomotion assembly  452  according to a further embodiment of the invention is illustrated, wherein like parts in the previous embodiments are represented by like numerals. The hull  450  is similar in construction to the hull  12  as shown in FIG. 7, with the exception of a large opening  453  formed in the upper wall  31 . A base frame  454  has an upper wall  456 , a pair of sidewalls  458 ,  460  located on either side of the upper wall  456 , and a peripheral mounting flange  462  that extends around a lower periphery of the side walls and upper wall. A rear portion of the upper wall  456  slopes generally upwardly and forwardly toward the bow from the peripheral mounting flange  462 . Preferably, the base frame  454  is constructed of plastic material and is molded as a unitary structure. A deck plate  464  is removably mounted in an opening in the rear portion of the upper wall. The deck plate  464  is removable by a user in order to provide access to the propeller  196  for removing underwater plants or other foreign matter that may become entangled in the propeller and hinder or stop its rotation. In this manner, it is unnecessary for the user to exit the watercraft when the propeller is entangled in order to make the necessary corrections. 
     As best shown in FIG. 19, the pedal tower  100  is connected to the base frame  454  with the legs  108  and  110  of the inverse U-shaped bracket  106  straddling the upper wall  456  and the side walls  458 ,  460 . A fastener  466  extends through each leg  108 ,  110  and their respective side walls  458 ,  460 . As in the previous embodiments, the pedal tower  100  is preferably pivotally connected to the base frame  454  through the fasteners  466  and can be locked to any pivotal position in order to adjust the relative distance between the pedals  130  and a seat (not shown). 
     A modular propulsion unit  470  includes a housing  472  with an upper end that rotatably mounts the lower sprocket wheel  164  and a lower end that rotatably mounts the propeller  196 . The lower sprocket wheel  164  is connected to drive the propeller  196  through any well-known coupling means (not shown) located within the housing  472  such as a drive shaft and cooperating bevel gears, a flexible drive cable, a drive belt or chain and pulley or sprocket wheel system, and so on. Details of an exemplary coupling means can be found in U.S. Pat. No. 4,459,116 issued to Moore on Jul. 10, 1984, the disclosure of which is hereby incorporated by reference. 
     A pair of pivot brackets  474  are fixedly mounted to opposite sides of the housing  472  through fasteners  476  and are pivotally connected to the side walls  458 ,  460  of the base frame  454  opposite the legs  110 ,  108 . Preferably, the fasteners  466  that pivotally mount the tower  100  to the base frame also pivotally mount the brackets  474  such that the rotational axis of the pedal tower  100  is coincident with the rotational axis of the modular propulsion unit  470 . In this manner, the pedal tower and propulsion unit can pivot independently of each other while maintaining the required distance between the lower sprocket wheel and upper sprocket wheel to keep the chain  166  taught, and while maintaining the distance between the lower sprocket wheel and the propeller  196 . 
     A handle or lever arm  478  is fixedly connected to one of the pivot brackets  474  and extends outwardly through an opening  465  in the upper wall  456  of the base frame  454 . Applying a force to the handle  478  in a direction as represented by arrow  480  in FIG. 17 causes the modular propulsion unit  470  to rotate from an extended in-use position to a retracted position in the tunnel  32 , as shown in FIG.  18 . This feature is especially convenient during transportation or when the watercraft is beached along a shore line. Although not shown, a bracket, cable, hook, ledge, or other means for holding or locking the modular propulsion unit  470  in the retracted and/or extended position can be provided. 
     With reference now to FIG. 20, a locomotion assembly  500  for use with the hull  450  according to a further embodiment of the invention is illustrated, wherein like parts in the previous embodiments are represented by like numerals. The locomotion assembly  500  is similar in construction to the locomotion assembly  452  previously described, with the exception that the upper sprocket wheel  126  is replaced with an upper gear  502  and the lower sprocket wheel  164  is replaced with a lower gear  504 . The upper and lower gears are preferably constructed of a durable, water-resistant or waterproof material, such as nylon. The upper gear  502  has teeth  506  that mesh with teeth  508  of the lower gear  504  such that rotation of the pedals  130  causes rotation of the upper gear  502 , which in turn causes rotation of the lower gear  504  to thereby drive the propeller  196 . A pedal tower  510  (shown in hidden line) is similar in construction to the pedal tower  100  but preferably has a fixed length since it is no longer necessary to install or replace the drive chain or to adjust its tension. This arrangement is particularly advantageous over the previous sprocket wheel and chain embodiments, since there are fewer parts, no adjustments between the gears are needed, and are not subject to corrosion. 
     Although described in conjunction with the locomotion assembly  500 , it is contemplated that the upper and lower gears can replace the upper and lower sprocket wheels and drive chain(s) of the previously described embodiments. 
     It is to be understood that the terms inner, outer, upper, lower, horizontal, vertical, and their respective derivatives, as used throughout the specification refer to relative, rather than absolute orientations and/or positions. 
     While the invention has been taught with specific reference to the above-described embodiments, those skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and the scope of the invention. For example, in each of the above embodiments one or more of the foot pedals can be replaced with hand pedals for accommodating handicapped persons or for exercising the upper body. 
     Thus, 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 that come within the meaning and range of equivalency of the claims are to be embraced within their scope.