Abstract:
Ventilated sponsons, personal watercraft having ventilated sponsons, and methods for adjusting the handling characteristics of personal watercraft by ventilating the sponsons. The present invention provides ventilated sponsons, sponsons, having holes formed through the sponsons to allow high pressure water trapped under the sponson to escape. The holes formed through the sponson thus allow for fine tuning and adjusting the performance characteristics and handling characteristics of the personal watercraft long after the point of manufacture. Ventilating the sponsons can increase straight line stability while maintaining tight cornering characteristics.

Description:
FIELD OF THE INVENTION 
     The present invention is related generally to personal watercraft. More specifically, the present invention is related to personal watercraft having adjustable sponsons. 
     BACKGROUND OF THE INVENTION 
     Personal watercraft have become increasingly popular in recent years. A personal watercraft, also known as a “jet ski” typically has a bottom hull, handle bars for steering, a tunnel within the bottom hull, a jet pump located within the bottom tunnel, and an engine within the hull under the top deck for driving the jet pump. The jet pump typically pulls in water from the front of the tunnel under the boat, and discharges the water at high velocity through a steerable nozzle at the rear of the boat. The handle bars are typically coupled to the nozzle, which is the steering mechanism for the personal watercraft. The watercraft commonly has a straddle-type seat and foot wells disposed on either side of the seat. 
     Early watercraft often had longitudinal chines running underneath the bottom hull, and sometimes had steps located in the rear portion of the bottom hull, for reducing porpoising by extending the length of the boat while not extending the length of wetted surface. Steering, as previously indicated, was primarily effected by turning the handle bars coupled to the nozzle, which could be steered from side to side to direct the water jet in the desired direction and thereby steer the personal watercraft. The steerable nozzle sometimes had a small rudder on the nozzle, also for aiding in steering the watercraft. 
     Early personal watercraft sometimes skidded around corners wider than the driver desired. Sometimes, boats would turn 180°, despite the driver&#39;s intent to make a sharp 90° turn. This lack of control at high speeds during aggressive maneuvers was later addressed by adding sponsons to the personal watercraft. 
     The term “sponson” has come to have different meanings in different contexts. Historically, sponsons were floatation devices or outriggers for stabilizing a boat in rough water. The sponsons could be lowered to stabilize a boat in rough water, for example, while fishing. The sponsons could be later raised for traveling through the water. The term sponson has also been used to refer to the outrigger on an outrigger canoe. As used in the personal watercraft industry, and as used in the present application, the term sponson refers to a device having a generally hydrodynamic shape to aid in the watercraft in stabilizing straight ahead progress through the water and to aid in executing turns in the water. The personal watercraft sponsons are dimensioned and configured to have a fin or blade having an outwardly extending edge that penetrates below the water level during normal use. The personal watercraft&#39;s sponson will penetrate below the water surface when the personal watercraft is at rest, in calm water, even with no rider on board. The sponson typically has an outwardly extending lower surface that rides on the water when the boat is planing. 
     Sponsons provide lift at the rear of the personal watercraft, acting to force the nose down to provide a degree of aggressiveness. Sponsons that provide harder, sharper cornering often also provide decreased straight line stability. The more aggressive design often has a “tippy” feeling when the rider shifts their weight. This tippy feeling is accepted by experienced drivers, but maybe unsettling to inexperienced drivers. Sponsons are typically designed together with the personal watercraft hull, for a particular model and year. Various considerations go into the hull and sponson design, including the desired degree of stability, desired lift provided by the sponson, and the degree of aggressiveness desired for that model and model year. Different drivers desiring different features can select varying personal watercraft having the desired handling characteristics. 
     What would be desirable are personal watercraft having sponsons which can vary according to the desired handling characteristics of the driver. What would be advantageous are sponsons which can be changed from an aggressive handling mode to a gentle riding mode. 
     SUMMARY OF THE INVENTION 
     The present invention provides ventilated sponsons, personal watercraft having ventilated sponsons, and methods for changing the handling characteristics of personal watercraft by forming holes in the sponsons. The present invention provides personal watercraft having sponsons that can extend outwardly and downwardly away from the hull of the personal watercraft, and have a downward and outward-most edge for penetrating beneath the water surface during use. The sponson body can have at least one hole formed through the body to relieve pressure formed along the underside of the sponson body. The holes&#39; diameter can vary with the particular embodiment. In some embodiments, the hole varies between about one-half inch and about one inch in diameter. The number of holes in some embodiments vary between one hole per sponson and about 5 holes per sponson. 
     Sponsons typically provide lift at the rear of a personal watercraft, raising the stern and lowering the bow, to provide a more aggressive handling and cornering machine. The outer edges of the sponson provide straightline stability by acting as a fixed rudder on either side of the hull. The outermost edges of the sponson also provide for tighter cornering by digging into the water during turns. In some situations, the driver may wish for improved straightline stability for a particular machine. Rather than being stuck with the particular handling characteristics of the particular personal watercraft, the present invention provides methods for adjusting the handling characteristics of the personal watercraft. Holes can be formed through the sponson body, to the underside of the sponson, to bleed off pressure formed along the underside of the sponson. In normal use, when the personal watercraft is planing, substantial water pressure is built up under the sponson, with a sponson horizontal surface typically riding on the surface of the water. Holes can be formed through the sponson body to allow a spray of water to exit through the hole, thereby relieving the pressure in the rear of the watercraft, thereby raising the nose of the watercraft. In some watercraft, the holes are between about one-half inch and one inch in diameter. In some sponsons, the holes have a pitch of about 10 degrees upward from a rearward facing horizontal direction and an outward angle of about 30 degrees away from a directly rearward facing orientation. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a rear, perspective view of a personal watercraft having curved, ventilated sponsons; 
     FIG. 2 is a fragmentary, rear view of the curved, ventilated sponson of FIG. 1, having a hole through the sponson shown in phantom; 
     FIG. 3 is a top view of one sponson from FIG. 1 illustrating the outward angle of the holes through the sponson; 
     FIG. 4 illustrates the sponson of FIG. 1 from a side view, illustrating the upward angle of the holes through the sponson; and 
     FIG. 5 is a fragmentary, rear view of another personal watercraft having a ventilated sponson including an outwardly extending portion and a downwardly extending fin portion. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following detailed description should be read with reference to the drawings, in which like elements in different drawings are numbered identically. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. Several forms of invention have been shown and described, and other forms will now be apparent to those skilled in art. It will be understood that embodiments shown in drawings and described above are merely for illustrative purposes, and are not intended to limit scope of the invention as defined in the claims which follow. 
     FIG. 1 illustrates a personal watercraft  20  having generally a front or bow  22  and a rear or stern  23 . Personal watercraft  20  includes a bottom hull  24  secured to a top deck  26  along an overlapping portion covered with a rub rail  32  in the embodiment illustrated forming a hull. 
     The hull formed by the bottom hull  24  and top deck  26  define a compartment sized to contain an internal combustion engine for powering the watercraft, and may also include one or more storage compartments, depending upon the size and configuration of the watercraft. The deck portion  26  also has a raised, longitudinally extending seat  28  adapted to accommodate one or more rider seated in straddle fashion on the seat  28 . The engine powers a jet propulsion unit  29 , typically mounted in a tunnel at the bottom rear portion of the watercraft. The jet propulsion unit  29  includes a steerable water discharge nozzle  51  that is operatively connected to a set of handlebars  42  to facilitate steering of the watercraft by the operator. The handlebars  42  typically mount through a top portion of a shroud  40 . Connection between the handlebars  42  and the discharge nozzle  51  may be of any suitable type, and typically includes mechanical linkages including a control cable. If desired, an electronic connection could also be utilized. 
     FIG. 1 illustrates a ventilated sponson  50 . Ventilated sponson  50  includes generally a curves sponson fin being curved outwardly and downwardly away from hull  24 . Ventilated sponson  50  includes mounting holes  52  for mounting the sponson to hull  24 . Ventilated sponson  50  may be seen to have numerous braces or ribs  54  for providing support and structural strength to the sponson  50 . Downwardly curved, inter-rib portions  58  separate the ribs  54 . Inter-rib sponson portions  58  may be seen to include a plurality of holes  56  formed through the sponson. Holes  56  may be seen to be partially or entirely open through the sponson. Holes  56  can provide a path for water trapped on the underside of the sponson to exit to the upper or outside of the sponson through the sponson body. Sponson  50  may be seen to include an outward or downward-most edge  60  that penetrates the water surface. In a preferred embodiment, ventilated sponson  50  is dimensioned, configured and mounted on hull  24  such that sponson edge  60  lies beneath the water surface when personal watercraft  20  is at rest or in calm water, even with no passengers. Sponson  50  thus provides a hydrodynamic steering function, rather than a flotation function. In a preferred embodiment, ventilated sponson  50  is formed of a material, such as polypropylene, which is heavier than water and thus does not float. Sponson  50  may also be formed in a manner so as to be non-buoyant. 
     FIG. 2 illustrates a portion of personal watercraft  20  from the rear, illustrating ventilated sponson  50  in greater detail. Ventilated sponson  50  may be seen to include downward and outward-most extending edge  60 , as well as a concave region  61  which can trap water beneath sponson  50 . Hole  56  may be seen to provide an egress path for water trapped under sponson  50  in concave region  161 . As may be seen from inspection of FIG. 2, hole  56  is angled upward relative to horizontal, as it is in a preferred embodiment of the present invention. 
     FIG. 3 illustrates a top view of sponson  50  from FIG. 1, further illustrating ribs  54 , inter-rib regions  58 , and holes  56 . Holes  56  are illustrated forming an angle (indicated at  64 ) relative to a vertical plane drawn through the sponson or watercraft. In a preferred embodiment, holes  56  are formed so as to form an angle of between about 10 and 40 degrees, most preferably about 30 degrees, away from a vertical plan drawn through the sponson, relative to a directly rearward facing hole. The holes are preferably round, but being illustrated as elliptical in FIG. 3 due to the curved surface into which the round holes are formed. In some sponsons, the holes are about ¾ inch in diameter and spaced about 2-4 inches apart. 
     FIG. 4 illustrates a side view of the ventilated sponsons of FIGS. 1 and 3. FIG. 3 illustrates that holes  56  can form an angle as indicated at  66 , relative to a horizontal plane drawn through the sponsons. In a preferred embodiment, holes  56  form an angle of between about 5 and 20 degrees upward of horizontal, most preferably about 10 degrees upward. The holes can thus form an angle of about 10 degrees upward from horizontal and about 30 degrees forward and outward of a rear vertical plane through the sponson. 
     FIG. 5 illustrates a portion of another watercraft  120  having a ventilated sponson  150  affixed to the bottom hull  124 . Ventilated sponson  150  includes generally a horizontally or outwardly extending portion  152  continuing onto a downwardly extending portion or fin  154 , terminating in a downwardmost edge of the fin at  160 . A hole  156  may be seen formed through fin  154 . A cavity  161  may be seen formed under ventilated sponson  150 , illustrating the location in which high pressure water can be trapped during travel. The high pressure travel can exit through hole  156 . 
     The present invention includes methods for modifying the handling characteristics of a personal watercraft, both at the factory and after delivery to a user. A sponson not ventilated or minimally ventilated may provide aggressive handling and tight cornering characteristics. The sponsons may also provide less stability than desired by the driver. 
     In particular, the lift provided by water trapped under the sponson out plane speeds may be larger than the driver desires, providing less than desired straight-line stability. Holes can be formed in the sponson to bleed off some of the pressure. Some water could spray out of the holes decreasing lift, and raising the nose of the watercraft, straight-line stability can be increased while maintaining tight cornering characteristics.