Abstract:
A watercraft propelled by a water jet includes an sealed hull portion including an upper deck and a bottom surface, an engine compartment located behind the sealed hull portion and containing a propulsion and steering system including an engine, a bladed impeller driven by the engine for inducting water and forcing the inducted water away from the craft through a directionally displaceable nozzle, and a control lever located on the upper deck including an engine throttle control and a steering control for adjusting the directionally displacement of the nozzle.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates generally to a boat propelled by a water jet. In particular, the invention pertains to a kayak-like watercraft powered by an engine, and having a hull on which the rider sits and controls speed and direction. 
         [0003]    2. Description of the Prior Art 
         [0004]    Traditional kayaks typically accommodate one, two or occasionally three riders who sit facing forward in one or more cockpits below the deck of the boat and propel the craft by paddling. A waterproof cover attaches securely to the edges of the cockpit, preventing entry of water, and making it possible for the boat to roll upright again without the boat filling with water after tipping over. 
         [0005]    Increasingly, manufacturers are building leisure “sit-on-top” variants of the traditional kayak with a fixed rudder for directional stability. Water that enters the cockpit drains out through holes or tubes that run from the cockpit to the bottom of the hull. Sit-on-top kayaks usually come in single and double paddler designs and are particularly popular for fishing and SCUBA diving, since such riders must easily enter and exit the water, change seating positions, and access hatches and storage wells. Ordinarily the seat of a sit-on-top is slightly above water level, so that the center of gravity of the paddler is higher than in a traditional kayak. To compensate for the center of gravity, a sit-on-top is often wider than a traditional kayak of the same length, and is slower. 
         [0006]    Attempts have been made to provide a power source to propel kayaks, but the inherent instability of the hull and the susceptibility of the engine to damage in the event of a tip over is a serious consideration. 
         [0007]    A need exists for a powered “sit-on-top kayak that provides simple, convenient, intuitive control of the engine and steering. The hull and engine compartment should be sealed against entry of water when the craft is upright or tipped over, yet provide for air to enter the engine through the engine compartment. The craft should have high strength, low weight, little vibration and provide excellent floatation. 
       SUMMARY OF THE INVENTION 
       [0008]    A watercraft propelled by a water jet includes a sealed hull portion including a bottom surface and an upper deck defining a space containing material for reinforcing the upper deck and bottom surface against damage, the upper deck being formed with a seat and including a seat back for supporting a rider located in the seat. An engine compartment, located behind the seat, contains an engine, a bladed impeller located behind the engine and driven by the engine, for inducting water and forcing the inducted water away from the rear of the watercraft through a nozzle. The nozzle is supported to pivot about a first axis. A control lever located on the upper deck is supported to pivot about a second axis and is operatively connected to the nozzle, for pivoting the nozzle about the first axis in response to pivoting the control lever about the second axis. 
         [0009]    The rider sits on the upper deck with legs extended along the deck and straddling the control lever. An accelerator for adjusting engine speed and starting and stopping the engine are located on the control lever. The craft is steered and maneuvered by pivoting the control lever rightward and leftward, thereby causing the nozzle to pivot and direct the water jet in a direction that causes the watercraft to turn in the direction that the lever is pivoted. 
         [0010]    The hull is divided by a partitioning wall or bulkhead between the rider sitting area and the engine compartment. The engine compartment occupies a small space. 
         [0011]    An air intake and cowling allow the craft to roll over upside-down without inducting water into the engine compartment. This feature enables the engine to be readily restarted following a rollover event. 
         [0012]    Space between the upper deck and bottom surface contains a core material that strengthens and reinforces the deck and bottom surface against damage due to impact with a foreign object, thereby avoiding dents and other surface defects that would impair high performance operation. The hull and engine compartment are fully sealed to enhance floatation, achieving high strength with low weight, little vibration and excellent floatation characteristics. 
         [0013]    The control lever pivots downward to facilitate storage of the craft in a compact space. 
         [0014]    The scope of applicability of the preferred embodiment will become apparent from the following detailed description, claims and drawings. It should be understood, that the description and specific examples, although indicating preferred embodiments of the invention, are given by way of illustration only. Various changes and modifications to the described embodiments and examples will become apparent to those skilled in the art. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0015]    The invention will be more readily understood by reference to the following description, taken with the accompanying drawings, in which: 
           [0016]      FIG. 1  is a side view of a kayak propelled by a water jet; 
           [0017]      FIG. 2  is a top view of the kayak shown in  FIG. 1 ; 
           [0018]      FIG. 3  is a cross sectional side view of the kayak shown in  FIG. 1 ; 
           [0019]      FIG. 4  is a top view of the kayak shown in  FIG. 3 ; and 
           [0020]      FIG. 5  is a cross section of the air inlet taken at plane  5 - 5  of  FIG. 2  and showing the air duct open. 
           [0021]      FIG. 6  is a cross section of the air inlet showing the air duct closed by a sealing valve. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0022]    Referring now to  FIGS. 1-4 , a kayak  10  includes a sealed hull portion  12  covered with a seamless molded plastic skin, which preferably is a composite material that includes a plastic matrix reinforced with stands of fiberglass, carbon or Kevlar. The skin may be formed of HDPE laminated polymer plastic. 
         [0023]    The hull is formed with a recess  14  on its upper surface  15 , in which recess the rider sits facing forward with legs straddling a manually-operated control lever  16  (called a joystick) and feet supported on foot rests  17 ,  18 . The volume of hull  12  between its upper deck  15  and its bottom surface  17  is filled with a core material  20  that reinforces, strengthens and stiffens the hull. The material of the core  20  may be machined or preferably expanded polystyrene foam, or expanded polyurethane foam. Alternatively, the core material may be a hollow, hexangular honeycomb of Kevlar or a similar synthetic material. The hull portion  12  is sealed, thereby preventing entry of water from waves or spray and making it possible to roll the kayak upright again without it filling with water following a tip over. 
         [0024]    A seat back  22 , secured to the upper surface of the hull  12  supports the seated rider. The core reinforced portion of the hull  12  is closed by a partition or bulkhead  24 , located at the forward end of an engine compartment  26 , which contains an engine  28 , water intake duct  30 , bladed impeller  32  that forces water from the intake duct, and a nozzle  34 , whose angular position about a vertical axis can be varied leftward and rightward to steer the kayak  10 . Water inducted through duct  30  flows through the impeller and exits through the nozzle  34 . 
         [0025]    The engine compartment  26  is covered with a cowling  36  formed with an air inlet passageway  38 . Cowling  36  is secured by latches  40 ,  41  to the upper surface  15  of the hull, thereby sealing the engine compartment  26  against entry of water when the cowling is latched to the hull. 
         [0026]    The intake duct  30 , which may be a component separate from the hull  12  or formed integrally with the hull, is of molded plastic having an intake opening  44  in the bottom of the hull, through which water is inducted and flows toward the outlet of nozzle  34 . A driveshaft  46 , secured to the crankshaft of engine  28  drives the bladed impeller  32 . A water jet, which propels and steers the kayak  10 , rises from the outlet of nozzle  36  into the air above the water surface. 
         [0027]    The rider pivots the joystick  16  leftward and rightward about an axis  48  to steer the craft. The rider also pivots the joystick  16  upward and downward about axis  49  to locate its hand grip in a comfortable position during use and in a downward position when the craft  10  is stored or being transported. As the joystick  16  pivots, cables  50 ,  52 , supported on pulleys, transmit movement of the joystick to a steering controller  54 , which pivots about an axis  56  in response to pivoting of the joystick  16  about axis  48 . 
         [0028]    Nozzle  34  also pivots about axis  56  as the joystick pivots, thereby steering and maneuvering the kayak leftward and rightward by redirecting the water jet exiting the nozzle relative to the longitudinal axis of the craft. 
         [0029]    The joystick  16  carries a button  58 , which is depressed to start engine  28 ; a button  60  that stops the engine; or a single button having an engine starting state and a stopping state; a kill switch and, an engine throttle in the form of a trigger  64  located on the underside of the joystick, by which the engine throttle is opened and closed to control engine speed and speed of the kayak  10 . 
         [0030]      FIG. 5  shows the air inlet  38  supported on the cowling  36  above the engine compartment  26 . The inlet  38  is of molded plastic having a forward facing opening  70 , a frame  72  having an inclined opening  74 , and a duct  76  that carries air rearward toward two laterally aligned circular cylindrical air ducts  78 . The end of duct  76  is closed by a wall  80  having at its base a drain  82 , through which water and air may be carried from the inlet  38  to the engine compartment  26 . 
         [0031]    Each air duct  76  is supported by a flange  84  seated on the upper surface of cowling  38 . The outer surface  86  of each duct  78  may be formed with an external screw thread, which is engaged by a jam nut contacts the lower surface of cowling  36 , thereby securing the duct to the cowling. Alternatively, the mounting flange  84  of each duct  78  is bonded to the upper surface of cowling  36  to secure the duct to the cowling. 
         [0032]    A flexible rubber flapper seal valve  88  includes a leg  90  that is secured to the lower outer surface of frame  72 , and a panel  92  that extends laterally across the width and longitudinally across the height of opening  74  when the flapper seal  88  is closed. Panel  92  is made of material that is lighter than water. Preferably its specific weight is in the range from 0.6 to 0.9. A circular recess  94 , formed at the base of panel  92 , facilitates flexural movement of the panel from its normally-open position, which is shown in  FIG. 5 , to its closed position, at which the panel overlaps and becomes seated on the flat surface  96  along the perimeter of opening  74 , thereby closing the opening, shown in  FIG. 6 . 
         [0033]    In operation, if the kayak  10  were to overturn in the water, flapper seal valve  88  would immediately close the opening  74  due to the weight of panel  92  pivoting at recess  94 . Water then fills the space  98  that is external to opening  74  and panel  92 , forcing the panel into contact with surface  96 , thereby positively sealing opening  74  against water leakage into duct  76 . The seal  88  prevents water from entering the engine compartment through the air ducts  78 . When water leaves space  98  and the kayak is turned upright, flapper seal  88  immediately opens, permitting air to be drawn into the engine compartment and into the engine  28 . 
         [0034]    If the kayak  10  were submerged under water in the upright position shown in  FIG. 5 , panel  92  would float upward to the position shown in  FIG. 6  due to its specific weight being lower than that of water. Water then flows into space  98  toward the opening  74 , forcing the panel into contact with surface  96 , thereby positively sealing opening  74  against water leakage into duct  76 . The seal  88  prevents water from entering the engine compartment through air ducts  78 . When water leaves space  98 , flapper seal  88  immediately opens, permitting air to be drawn into the engine compartment and into the engine  28 . 
         [0035]    In accordance with the provisions of the patent statutes, the preferred embodiment has been described. However, it should be noted that the alternate embodiments can be practiced otherwise than as specifically illustrated and described.