Abstract:
An amphibious vehicle achieves a stable ride, maneuverability, and high speed. The vehicle includes a hull having a “V” center portion with outboard sponsons. The sponsons reside between the front wheel wells and the rear wheels wells for improving lift and transition to planing. Shallow tunnels begin in rear portions of the front wheel wells and taper into the sponsons to release water trapped in the wheel wells. Inward facing turning edges also reside between the front and rear wheel wells and improve in-water handling. Wheels are retractable by pneumatic cylinders in parallel with air shock absorbers and suspension cutout in the hull allow the suspension to lower through the hull. Flaps reside under suspension members and rise to cover the suspension cutouts when the wheels are retractable when the wheels are raised to reduce drag. A Morse cable couple a rack and pinion unit to a jet drive.

Description:
The present application claims the priority of U.S. Provisional Patent Application Ser. No. 60/969,673 filed Sep. 3, 2007 and is a Divisional of U.S. patent application Ser. No. 12/203,146 filed Sep. 3, 2008 and issued Jul. 17, 2012 as U.S. Pat. No. 8,221,174, which applications are incorporated in their entirety herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to amphibious vehicles and in particular to an amphibious vehicle capable of operation in rough water and high in-water speeds. 
     Amphibious vehicles have been known for many years. It has been reported that only one amphibious vehicle has been made in commercial production. That amphibious vehicle was the Amphicar, which was built in Germany from 1961 to 1968. This vehicle had a top speed of only 7 mph in water. The Amphicar, was driven in the water by a pair of propellers. 
     In June 2004, a Gibbs Aquada set a record for crossing the English Channel by averaging over 13 miles per hour and having a top speed of approximately 30 miles per hour. 
     Another amphibious vehicle, the Watercar disclosed in U.S. Pat. No. 6,808,430 filed by the present applicant, achieves in-water speeds of approximately 45 miles per hour. The Watercar has a frame which supports a body which has a buoyant hull portion. The Watercar suspension includes coil over shock absorbers and the top mounting points of the coil over shock absorbers are mounted to cylinders allowing the front and rear wheels to be retracted (raised) by lifting the coil over shock mounting points. A water jet pump assembly is supported in the body and has a water intake in the bottom of the hull portion. An impeller moves water rearwardly to a water outlet jet at the stern of the hull portion of the vehicle. An engine is supported by the frame and is mounted over the water jet pump assembly. The engine drives both the wheels and the water jet pump selectively through a power transfer assembly. The frame of the Watercar has two longitudinal frame members joined near the bow by a bridge frame supporting the front wheel controls, and at the rear by a rear bridge frame extending upwardly and connected by a cross member. Port and starboard front and rear wheel bottom plates extend from a recessed position to an extended position where they slide under the raised wheels. The in-water character of the Watercar is basically that of a flat bottom boat without a scag. A scag was not included because of road clearance during on-land use, and the cost and difficulty of including a deployable scag. As a result of the absence of the scag, the Watercar does not turn as well as it might had it included a scag and flat bottom boats generally have a poor ride in rough water. Further, some features of the Watercar are expensive to manufacture and results in a fairly expensive product. The &#39;430 patent is herein incorporated in it&#39;s entirety by reference. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention addresses the above and other needs by providing an amphibious vehicle which achieves a stable ride, maneuverability, and high speed. The vehicle includes a hull having a “V” center portion with outboard sponsons. The sponsons reside between the front wheel wells and the rear wheels wells for improving lift and transition to planing. Shallow tunnels begin in rear portions of the front wheel wells and taper into the sponsons to release water trapped in the wheel wells. Inward facing turning edges also reside between the front and rear wheel wells and improve in-water handling. Wheels are retractable by pneumatic cylinders in parallel with air shock absorbers and suspension cutout in the hull allow the suspension to lower through the hull. Flaps reside under suspension members and rise to cover the suspension cutouts when the wheels are retracted to reduce drag. A Morse cable couples a rack and pinion unit to a jet drive. 
     In accordance with one aspect of the invention, there is provided an amphibious vehicle comprising a frame, two front wheels supported by the frame, two rear wheels supported by the frame, a hull carrying the frame, a body carried above the hull, a power plant providing power, a jet drive, and a drive mechanism. The hull includes a bow, a stern, a bow portion extending from the bow to the at least one front wheel, a mid portion between the at least one front wheel and the rear wheels, a stern portion extending form the rear wheels to the stern, a “V” shaped longitudinal center portion extending along a centerline of the hull from the bow to the stern, and sponsons extending along outside edges of the hull between the at least one front wheel and the rear wheels. The jet drive receives power from the power plant and resides inside the hull at the stern of the hull for providing in-water propulsion. The drive mechanism receives power from the power plant for driving the rear wheels for providing on-land propulsion. Front wheel wells are provided for the front wheels and rear wheel wells for the rear wheels and both the front and rear wheel wells are formed in the hull and/or the body. Port and starboard tunnels sweep downward and sternward behind each front wheel well and taper shallower towards the port and starboard rear wheel wells respectively for providing a smooth path for water caught in the front wheel wells to escape. 
     In accordance with another aspect of the invention, there is provided an amphibious vehicle comprising a frame, two front wheels supported by the frame, two rear wheels supported by the frame, a hull carrying the frame, a body carried above the hull, a power plant providing power, a jet drive, and a drive mechanism. The hull includes a bow, a stern, a bow portion extending from the bow to the at least one front wheel, a mid portion between the at least one front wheel and the rear wheels, a stern portion extending form the rear wheels to the stern, a “V” shaped longitudinal center portion extending along a centerline of the hull from the bow to the stern, and sponsons extending along outside edges of the hull between the at least one front wheel and the rear wheels. The jet drive receives power from the power plant and resides inside the hull at the stern of the hull for providing in-water propulsion. The drive mechanism receives power from the power plant for driving the rear wheels for providing on-land propulsion. Front wheel wells are provided for the two front wheels and rear wheel wells for the rear wheels, both the front and rear wheel wells formed in the hull and/or the body. Port and starboard, front and rear suspension cutouts are formed in the hull bottom vertically aligned with the port and starboard front and rear suspension respectively. 
     The front and rear suspension is lowerable to the lowered positions through the suspension cutouts when the wheels are extended for on-road driving, and the control arms raisable to the raised positions above the suspension cutouts then the wheels are retracted for in-water driving. Port and starboard front and rear flaps are vertically aligned with the suspension cutouts. The flaps reside planar to the bottom of the hull when the control arms are in the raised positions for smoothing at least a portion of the suspension cutouts with the hull, and the flaps are lowerable to vertically separate from the bottom of the hull to allow the suspension control arms to assume the lowered positions. The combination of cutouts and flaps is important because the cutouts allow greater wheel lowering and thus greater ground clearance to allow a “V” hull for on-road operation. The flaps reduce the drag which would otherwise result from the cutouts and the rear flaps in particular reduce drag near the stern to facilitate the transition to planing. 
     In accordance with yet another aspect of the invention, there is provided an amphibious vehicle comprising a frame, two front wheels supported by the frame, a rack and pinion steering unit for turning the front wheels for on-land steering, two rear wheels supported by the frame, a hull carrying the frame, a body carried above the hull, a power plant providing power, a jet drive, and a drive mechanism. The hull includes a bow, a stern, a bow portion extending from the bow to the at least one front wheel, a mid portion between the at least one front wheel and the rear wheels, a stern portion extending form the rear wheels to the stern, a “V” shaped longitudinal center portion extending along a centerline of the hull from the bow to the stern, and sponsons extending along outside edges of the hull between the at least one front wheel and the rear wheels. The jet drive receives power from the power plant and resides inside the hull at the stern of the hull for providing in-water propulsion. The drive mechanism receives power from the power plant for driving the rear wheels for providing on-land propulsion. A Morse cable is connected between the rack and pinion steering unit and the jet drive to turn the jet drive for in-water steering. The rack and pinion steering unit may be manual or a power rack and pinion steering unit and connection of the Morse cable to the steering arms provides a similar feel to on-land steering and to in-water steering. In a preferred embodiment, a sliding member and at least one spring allow for full lock to lock steering of the jet drive to correspond to about one half of the lock to lock steering of the front wheels. A more preferred embodiment includes a slotted bell crank which firmly holds the jet drive at a center position. 
     In accordance with yet another aspect of the invention, there is provided an amphibious vehicle comprising a frame, two front wheels supported by the frame, two rear wheels supported by the frame, a hull carrying the frame, a body carried above the hull, a power plant providing power, a jet drive, and a drive mechanism. The hull includes a bow, a stern, a bow portion extending from the bow to the at least one front wheel, a mid portion between the at least one front wheel and the rear wheels, a stern portion extending form the rear wheels to the stern, a “V” shaped longitudinal center portion extending along a centerline of the hull from the bow to the stern, and sponsons extending along outside edges of the hull between the at least one front wheel and the rear wheels. The jet drive receives power from the power plant and resides inside the hull at the stern of the hull for providing in-water propulsion. The drive mechanism receives power from the power plant for driving the rear wheels for providing on-land propulsion. Port and starboard, front and rear, control arms are moveably connected between the wheels and the frame inboard of the wheels for allowing vertical motion of the wheels. The control arms have control arm lowered positions for extending the wheels for on-road driving and control arm raised positions for retracting the wheels for in-water driving. Port and starboard, front and rear shock absorbers are connected between the control arms and the frame. Port and starboard cylinders are connected between the control arms and the frame in parallel with the shock absorbers for lifting the control arms to retract the wheel for in-water driving. Front and rear air bags are preferably included for supporting the frame (i.e., in place of spring). The air bags are filled with air to extend the wheels and the air is released from the air bags and pressure is applied to the air cylinders below internal pistons to retract the wheels. The front air bags are preferably air bag elements of the front shock absorbers and the rear air bags are preferably connected between the rear suspension and the frame in parallel with the rear shock absorbers. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       The above and other aspects, features and advantages of the present invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein: 
         FIG. 1  is a side view of an amphibious vehicle according to the present invention. 
         FIG. 2A  is a front view of the amphibious vehicle. 
         FIG. 2B  is a rear view of the amphibious vehicle. 
         FIG. 3  is a second side view of the amphibious vehicle. 
         FIG. 4  is a cross-sectional view of the amphibious vehicle taken along line  4 - 4  of  FIG. 3 . 
         FIG. 5  is a cross-sectional view of the amphibious vehicle taken along line  5 - 5  of  FIG. 3 . 
         FIG. 6  is a cross-sectional view of a port side leading edge flaring into a sponson according to the present invention, residing behind a front port side wheel taken along line  6 - 6  of  FIG. 4 . 
         FIG. 7A  is a top view of an amphibious vehicle frame and suspension according to the present invention. 
         FIG. 7B  is a side view of the amphibious vehicle frame and suspension. 
         FIG. 7C  is a front view of the amphibious vehicle frame and suspension. 
         FIG. 7D  is a rear view of the amphibious vehicle frame and suspension. 
         FIG. 7E  is a top view of a second embodiment of the rear suspension. 
         FIG. 7F  is a rear view of the second embodiment of the rear suspension. 
         FIG. 8A  is a side view of the amphibious vehicle with the wheels extended for on-road driving. 
         FIG. 8B  is a side view of the amphibious vehicle with the wheels retracted for in-water driving. 
         FIG. 9A  is a side view of the amphibious vehicle frame with suspension lowered to extend the wheels for on-road driving. 
         FIG. 9B  is a side view of the amphibious vehicle frame with the suspension raised to retract the wheels for in-water driving. 
         FIG. 9C  is a side view of the amphibious vehicle frame with the second embodiment of the rear suspension lowered to extend the wheels for on-road driving. 
         FIG. 9D  is a side view of the amphibious vehicle frame with the second embodiment of the rear suspension raised to lift the wheels for in-water driving. 
         FIG. 10A  is a side view of a hull according to the present invention with flap according to the present invention laying against the bottom of the hull. 
         FIG. 10B  is a bottom view of the hull showing control arm cutouts and the flaps covering the cutouts to smooth the cutouts with the bottom of the hull. 
         FIG. 10C  is a side view of the hull showing the flaps vertically separated from the hull to allow the control arms to move to a lowered control arm position for on-road driving. 
         FIG. 11A  shows front control arms lowered and pushing front flaps down according to the present invention. 
         FIG. 11B  shows front control arms raised and pulling front flaps up against the hull according to the present invention. 
         FIG. 12A  shows the rear suspension lowered and pushing rear flaps down according to the present invention. 
         FIG. 12B  shows the rear suspension raised and pulling the rear flaps up against the hull according to the present invention. 
         FIG. 12C  shows the second embodiment of the rear suspension lowered and pushing the rear flaps down according to the present invention. 
         FIG. 12D  shows the second embodiment of the rear suspension raised and pulling the rear flaps up against the hull according to the present invention. 
         FIG. 13A  shows a first embodiment of a land and water steering unit according to the present invention. 
         FIG. 13B  shows a second embodiment of a land and water steering unit according to the present invention. 
         FIG. 14  shows a Morse cable attached to the jet drive. 
         FIG. 15A  shows a top view of the second embodiment of a land and water steering unit in a centered position. 
         FIG. 15B  shows a top view of the second embodiment of a land and water steering unit in a partial left turn position. 
         FIG. 15C  shows a top view of the second embodiment of a land and water steering unit in a full left turn position. 
         FIG. 16A  shows a top view of the third embodiment of a land and water steering unit in a centered position. 
         FIG. 16B  shows a top view of the third embodiment of a land and water steering unit in a partial left turn position. 
         FIG. 16C  shows a top view of the third embodiment of a land and water steering unit in a full left turn position. 
         FIG. 17A  shows the amphibious vehicle in-water. 
         FIG. 17B  shows an interior side wall according to the present invention for allowing the doors to open while in-water without allowing water to enter the amphibious vehicle. 
     
    
    
     Corresponding reference characters indicate corresponding components throughout the several views of the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description is of the best mode presently contemplated for carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing one or more preferred embodiments of the invention. The scope of the invention should be determined with reference to the claims. 
     A side view of an amphibious vehicle  10  according to the present invention is shown in  FIG. 1 , a front view of the amphibious vehicle  10  is shown in  FIG. 2A , and a rear view of the amphibious vehicle  10  is shown in  FIG. 2B . The amphibious vehicle  10  includes a body  15  having a bow portion  10   a  ahead of front axles  35  (see  FIG. 7B ), a mid portion  10   b  between front and rear axles  43  (see  FIG. 7B ), a stern portion  10   c  behind rear axles, a bow  11 , and a stern  13 . A hull  20  of the amphibious vehicle  10  resides on the bottom of the amphibious vehicle  10 . The amphibious vehicle  10  is carried by front wheels  14   a  and rear wheels  14   b  for on-land driving. The front wheels  14   a  reside in front wheel wells  12   a  and the rear wheels  14   b  reside in stern wheel wells  12   b . Port and starboard sponsons  16   a  and  16   b  (also see  FIGS. 4 ,  5 , and  10 B) reside on lower outboard port and starboard sides of the amphibious vehicle  10  between the front and rear wheel wells  12   a  and  12   b , and a jet drive  18  resides at the stern of the amphibious vehicle  10  to provide in-water propulsion. The amphibious vehicle  10  includes a power plant  23  supported by a frame  32  (see  FIGS. 7A-7F ) and a drive mechanism  25  receiving power from the power plant  23  for driving the rear wheels  14   b  for providing on-land propulsion. 
     The hull  20  includes a “V” shaped longitudinal center portion  20   a  providing a better in-water ride in rough water and a narrow flat center most portion  20   b  towards the rear of the hull  20 . Unlike boat hulls, the hull  20  includes two bow wheel wells  12   a  and two stern wheel wells  12   b  interrupting the bottom surface of the hull  20 . The presence of the four wheel wells  12   a  and  12   b  both creates drag and reduces lift. Such drag and loss of lift affects a vehicle at moderate speeds when the vehicle is attempting to plane and a large portion of the hull is still wet. The sponsons  16   a  and  16   b  overcome these difficulties by providing additional surface (or lifting) area in the center portion  10   b  of the hull  20  of the amphibious vehicle  10 , which center portion  10   b  is wet at moderate speed providing lift. The wet area shifts back towards the stern of the hull  20  as speed increases, and planing at high speed does not require substantial lift from the sponsons  16   a  and  16   b , although aft ends of the sponsons  16   a  and  16   b  generally remain wet during high speed planing to provide improved stability. 
     The design of the sponsons is a balance between drag and lift and an optimal design is dependent on the length and design of the hull, and the weight and balance of the amphibious vehicle. A greater wet area improves lift, but also adds some to drag. Maintaining at least a small rear portion of the sponsons in the water at high speed improves stability. Generally, the depth of the sponson D S  relative to the depth of the hull D H  (see  FIG. 4A ) has the greatest affect on sponson hydrodynamics. The sponson design goal is to make the depth of the sponson D S  great enough to obtain lift at moderate speed and stability at high speed. The exact design to accomplish this goal for a specific hull design may require in-water testing. 
     A second side view of the amphibious vehicle  10  is shown in  FIG. 3 , a cross-sectional view of the amphibious vehicle  10  taken along line  4 - 4  of  FIG. 3  is shown in  FIG. 4 , a cross-sectional view of the amphibious vehicle  10  taken along line  5 - 5  of  FIG. 3  is shown in  FIG. 5 , and cross-sectional view of a leading edge  22   a , according to the present invention, of the sponson  16   a  taken along line  6 - 6  of  FIG. 4  is shown in  FIG. 6 . Port and starboard leading edges  22   a  and  22   b  reside between the port and starboard front wells  12   a  and  12   b  and the port and starboard sponsons  16   a  and  16   b  on each side of the “V” shaped longitudinal center portion  20   a  of the hull  20 . The port and starboard leading edges  22   a  and  22   b  sweep downward and sternward just behind the port and starboard front wheel wells  12   a  and  12   b  respectively and merge into the port and starboard sponsons  16   a  and  16   b  respectively for providing a smooth path for water caught in the front wheel wells  12   a  and  12   b  to escape to improve in-water lift and stability. The length of the sponsons L S , measured from the transition of the leading edges  22   a  and  22   b  to the sponsons  16   a  and  16 , is preferably between one half and two thirds of the length between the wheel wells L W , and is more preferably approximately two thirds of the length between the wheel wells L. 
     Inward facing port and starboard turning edges  17   a  and  17   b  preferably form inside edges of the sponsons  16   a  and  16   b  respectively. The turning edges  17   a  and  17   b  provide the important function of catching the water when the amphibious vehicle  10  is turned in the water, thus improving in-water responsiveness. The turning edges  17   a  and  17   b  are preferably between inside and outside edges of the wheel wells  12   a  and  12   b , and are more preferably aligned with inside edges of the wheel wells  12   a  and  12   b  (see  FIG. 10B ). The turning edges  17   a  and  17   b  are preferably vertical edges, but may be sloped, and preferably extend down a sponson depth D S  between 25 percent and 75 percent of a hull (or “V”) depth D H  below a highest point  20 ′ of the hull seen in the cross-sectional view of  FIG. 4A , and more preferably extend down the sponson depth D S  of approximately 50 percent of the hull depth D H  measured from the base of the turning edges  17   a  and  17   b . In the embodiment of  FIG. 4A , the cutting edge  17 A had a cutting edge height equivalent to the sponson depth D S . 
     While sponsons with an inside edge formed by the turning edges and sloping outward and upward from the turning edges (see  FIGS. 4 and 5 ) are preferred, any amphibious vehicle with hydrodynamic surfaces between the wheel wells providing lift at low and moderate speeds is intended to come within the scope of the present invention. any combination of turning edge and sponson between the wheel wells providing improved turning (the turning edges) and improved lift at low and moderate speeds (the sponsons) is intended to come within the scope of the present invention. For example, the turning edges may be at the outside edge of the sponsons (i.e., aligned with the outside edges of the wheel wells) and the sponsons may slope upward and outward to the turning edges. Further, when the turning edges are on the inside edge of the sponsons, the sponsons may have a flat nearly horizontal bottom, not rising or lowering. 
     Port and starboard negative chines  19   a  and  19   b  run along outside edges of the sponsons  16   a  and  16   b  between the front and rear wheel wells  12   a  and  12   b . The chines  19   a  and  19   b  reach outward and downward and reduce or eliminate water splashing into the amphibious vehicle  10  interior. 
     A top view of an amphibious vehicle frame  30 , front suspension control arms  34 , and rear suspension control arms  42  according to the present invention is shown in  FIG. 7A , a side view of the amphibious vehicle frame and suspension is shown in  FIG. 7B , a front view of the amphibious vehicle frame and suspension is shown in  FIG. 7C , and a rear view of the amphibious vehicle frame and suspension is shown in  FIG. 7D . The front suspension control arms  34  preferably comprise upper and lower lateral control arms (i.e., extending laterally between the front wheels  14   a  and the frame  30 ) connecting the front wheels  14   a  to the frame  30  to allow normal suspension motion for on-road driving and for allowing the front wheels  14   a  to be retracted for in-water driving. Front axles  35  are carried by the front control arms  34 . 
     While the embodiment described herein includes upper and lower front control arm and trailing arm rear suspension, such is merely a single embodiment of the present invention. Other embodiments may include trailing arm front suspension, A arm rear suspension, or McPherson struts at the front and/or rear. An amphibious vehicle including sponsons, turning edges, flaps for covering suspension openings, or steering according to the present invention is intended to come within the scope of the present invention regardless of the type of suspension used for on-road driving. 
     The rear suspension control arms  42  preferably comprise trailing control arms  42  connected between the frame  30  and the rear wheels  14   b . The trailing control arms pivot at a forward mounting point to allow normal suspension motion for on-road driving and for allowing the rear wheels  14   b  to be retracted for in-water driving. Rear axles  43  are carried by the rear suspension  42 . 
     Continuing with  FIGS. 7A-7D , front shock absorbers  36   a  are connected between the suspension control arms  34  and the frame  30  to damping motion of the front wheels  14   a . Front cylinders  38   a  are mounted in parallel with the front shock absorbers  36   a  and are connected to a pressure source so that when pressure is applied to bases of the cylinders  38   a  (i.e., below pistons in the cylinders  38   a ), the front wheels  14   a  are retracted for in-water driving. Similarly, rear shock absorbers  36   b  are connected between the rear suspension control arms  42  and the frame  30  to damping motion of the rear wheels  14   b . Rear cylinders  38   b  are mounted in parallel with the rear shock absorbers  36   b  and are connected to the pressure source so that when pressure is applied to bases of the cylinders  38   b  (i.e., below pistons in the cylinders  38   b ), the rear wheels  14   b  are retracted for in-water driving. Both the front shock absorbers  36   a  and cylinders  38   a  are preferably connected between the control arms and towers  44 . The towers  44  are preferably molded into the body for added strength and to seal the wheel wells to keep water out of the interior and engine compartment. 
     A top view of a second embodiment of the rear suspension  42 ′ is shown in  FIG. 7E , and a rear view of the second embodiment of the rear suspension  42 ′ is shown in  FIG. 7F . The rear suspension  42 ′ replaces the rear lifting cylinders  38   b  with second rear air bags  40 ′. The air bags  40 ′ are attached to the frame through a bracket at the air bag bottom, and to the rear suspension at the air bag top. When the air bags  40 ′ are inflated, the rear suspension  42 ′ is raised. 
     A side view of the amphibious vehicle  10  with the wheels  14   a  and  14   b  extended for on-road driving is shown in  FIG. 8A , a side view of the amphibious vehicle  10  with the wheels  14   a  and  14   b  retracted for in-water driving is shown in  FIG. 8B , a side view of the amphibious vehicle frame  30  with suspension control arms  34  and  42  lowered to extend the wheels  14   a  and  14   b  for on-road driving is shown in  FIG. 9A , and a side view of the amphibious vehicle frame  30  with the control arms raised to retract the wheels  14   a  and  14   b  for in-water driving is shown in  FIG. 9B . Preferably, air bags  41  and  40  are included to support the amphibious vehicle  10 , in place of more common springs. More preferably, the front shock absorbers  36   a  are air shock absorbers and most preferably the front shock absorbers include air bags  41  serially integrated into the front shock absorbers. More preferably, the rear suspension includes rear air bags  40  mounted in parallel with the rear shock absorbers  36   b  and cylinders  38   b . Such preferred arrangement of air bags  40  and  41  and cylinders  38   a  and  38   b  allows a simple and low cost extending (by removing the pressure from the cylinders and providing pressure to the air bags) of the wheels  14   a  and  14   b , and retracting (by providing the pressure from the cylinders and removing the pressure to the air bags) of the wheels  14   a  and  14   b.    
     A side view of the amphibious vehicle frame with the second embodiment of the rear suspension  42 ′ lowered to extend the wheels for on-road driving is shown in  FIG. 9C , and a side view of the amphibious vehicle frame with the second embodiment of the rear suspension  42 ′ raised to lift the wheels for in-water driving is shown in  FIG. 9D . The air bags  40 ′ replace the cylinders  38   b  and are attached to the frame through brackets at the air bag bottom, and to the rear suspension at the air bag top. When the air bag  40 ′ are inflated, the rear suspension  42 ′ is raised. 
     A side view of the hull  20  according to the present invention with port front flap  52   a  and port and rear flap  52   b  according to the present invention laying against the bottom of the hull  20  is shown in  FIG. 10A , a bottom view of the hull  20  showing port front and rear control arm cutouts  50   a  and  50   b  and starboard front flap  52   a  and starboard rear flap  52   b  covering starboard front cutout  50   a  and starboard rear cutout  50   b  respectively (not shown), to smooth the cutouts  50   a  and  50   b  with the bottom of the hull  20 , is shown in  FIG. 10B , and a side view of the hull  20  showing the flaps  52   a  and  52   b  vertically separating from the hull  20  to allow the control arms  34  and  42  (see  FIG. 7A-7D ), to move to a lowered control arm position for on-road driving, is shown in  FIG. 10C . The two front flaps  52   a  and the two rear flaps  52   b  cover control arm cutouts  50   a  and  50   b  respectively when the suspension is raised for in-water operation to reduce drag, allowing easier transition to planing. A water inlet  54  for the jet drive  18  resides laterally centered on the flat center most bottom portion  20   b  of the hull  20  near the stern  13 . The sponsons  16   a  and  16   b  are seen to reside in outside portions of the hull  12 ′ between the wheel wells  12   a  and  12   b.    
     A front view of the front suspension in a lowered position with the flap  52   a  pushed down by the lower control arm  34   a  is shown in  FIG. 11A  and a front view of the front suspension in a raised position with the flap  52   a  pulled up by a strap  53   a  attached to the lower control arm  34   a  is shown in  FIG. 11B  (also see  FIGS. 10A-10C ). The flap  52   a  is attached to the hull  20  along an inside edge  52   a ′ and moves downward when the suspension is lowered (see  FIG. 11A ). The strap  53   a  is preferably an elastic strap and allows for some freedom on tolerances. When the flaps  52   a  are raised, water is kept out of the front wheel suspension cutouts  50   a  reducing the potential for increased drag. The flaps  52   a  include vertical edge on the outside edge of the flap  52   a  to reduce the entry of water into the suspension cutout  50   a . The vertical edge may be from one to three inches high and vary along the length of the flap. 
     A rear view of the rear suspension in a lowered position with the flap  52   b  pushed down by the lower control arm  42   a  is shown in  FIG. 12A  and a front view of the rear suspension in a raised position with the flap  52   b  pulled up by a rear strap  53   b  attached to the lower control arm  42   a  is shown in  FIG. 12B . The flap  52   b  is attached to the hull  20  along a forward edge  52   b ′ and moves downward when the suspension is lowered (see  FIG. 10C ). The strap  53   b  is preferably not elastic (for example, is a cable or chain) and holds the flap  52   b  firmly against the hull  20  during in-water operation (also see  FIGS. 10A-10C ). The rear flaps  52   b  generally experience much greater water forces than the front flaps  52   a , and holding the rear flaps tightly against the bottom of the hull  20  is very important in reducing drag. The flaps  52   b  also have about a one inch vertical edge on the outside edge of the flap  52   b  to reduce the entry of water into the suspension cutout  50   b.    
     The second embodiment of the rear suspension  42 ′ lowered and pushing the rear flaps  52   b  down is shown in  FIG. 12C , and the rear suspension  42 ′ raised and pulling rear flaps  52   b  up against the hull according to the present invention is shown in  FIG. 12D . The air bags  40  are seen inflated to support the amphibious vehicle  10  during on road operation is seen in  FIG. 12C , and the air bags  40 ′ are shown inflated to lift the suspension  42 ′ for in-water operation is seen in  FIG. 12D . 
     A first embodiment of a land and water steering unit  60   a , according to the present invention, having a Morse cable  74  connected to a rack and pinion unit  64  is shown in  FIG. 13A . The connection of the Morse cable to the jet drive  18  through a rod  76  is shown in  FIG. 14 . A sliding inner cable  70  is connected to steering arms  66  which are connected to the front wheels  14   a  (see  FIG. 1 ) for on-land steering. The cable  70  is connected to a rod  76  connected to the nozzle of the jet drive  18  to steer in-water. The rack and pinion unit  60  may be a power rack and pinion steering unit or a manual rack and pinion steering unit. Such a direct cable connection between the steering arms  66  and the jet drive  18  provides a similar feel to on-land and in-water steering thus making the transition between in-water and on-land more natural. 
     A perspective view of a second embodiment of a land and water steering unit  60   b , according to the present invention, with the Morse cable  74  connected to the rack and pinion steering unit  64  is shown in  FIG. 13B  and top views of the second embodiment of a land and water steering unit  60   b  in different positions are shown in  FIGS. 15A-15C . In order to have the same land and water steering feel, some drivers prefer that the water steering is quicker than the land steering and with less turn lock to lock. To obtain such results, the land and water steering unit  60   b  including a spring  84  and slot  82  mechanism shown in  FIG. 13A  in a centered position. A rod  88  is connected to one of the steering arms  66  and translates with the steering arm  66  along arrow A1 (arrow A2 shows the same translation of the opposite steering arm  66 ). The opposite end of the rod  88  is attached to a sliding member  81  which slides in a slot  82  in a coupling device comprising an “L” shaped bell crank  80 . The bell crank  80  pivots at pivot  86  in the corner of the crank. A spring  84  is in tension between the pivot  86  and the sliding member  81  thereby pulling the sliding member  81  towards the pivot  86 . An inner Morse cable  70  attached to a cable end  87  of the bell crank  80  and motion of the steering arm  66  is thus translated into a motion of the inner Morse cable  70 . Preferably, the first approximately three inches of rack movement is directly translated to three inches of translation of the inner Morse cable. Additional motion of the rack is transmitted only to the front wheels. 
     While a land and water steering unit with an “L” shaped bell crank is disclosed above, any coupling device providing for a sliding member to couple initial movement of the steering arm away from center with a Morse cable, and to decouple further movement of the steering arm from the Morse cable is intended to come within the scope of the present invention. 
     A preferred steering ratio for on-land steering is between 2:1 and 3:1, and a more preferred ratio is approximately 3:1. A preferred steering ratio for in-water steering is between 1.5:1 and 2.5:1, and a more preferred ratio is approximately 1.5:1. The on-land steering is preferably 3 turns lock to lock, and the in-water steering is preferably 1.5 turns lock to lock. 
     Initial translation of the steering arms  66  along arrows A1 and A2 is shown in  FIG. 15B . The translation of the steering arms  66  results in a similar translation along arrow A3 of the rod  88 . The spring  84  holds the sliding member  84  at the end of the slot  82  nearest to the pivot  86 , and the translation of the rod  88  causes the bell crank  80  to rotate along arrow A4. The rotation of the bell crank  80  causes translation along arrow A5 of the inner Morse cable  70 . The inner Morse cable  70  is attached to the rod  76  (see  FIG. 14 ). Turning the steering wheel thus causes both turning of the front wheel for land steering and turning of the jet drive  18  (see  FIG. 12 ). 
     Full motion of the steering arm  66  is shown in  FIG. 15C . The bell crank  80  is prevented by stops from further rotation past the rotation shown in  FIG. 15B , and the spring  84  is stretched allowing the sliding member  84  to slide to the end of the slot  82  farthest from the pivot  86 , and there is no additional translation by the inner Morse cable  70  past the translation shown in  FIG. 15B . Thus full motion of the jet drive  18  is obtained during an initial translation of the steering arm  66 . 
     A top view of a third embodiment of a land and water steering unit  60   c , according to the present invention, with the Morse cable  74  connected to the rack and pinion steering unit  64  is shown in  FIG. 16A  and top views of the third embodiment of a land and water steering unit  60   c  in different positions are shown in  FIGS. 16B and 16C . The third embodiment of a land and water steering unit  60   c  provides the same benefits as the second embodiment  60   b , except without the bell crank  80 . The rod  88  slides through a second guide  90   b  and a third guide  90   c , both attached to the rack and pinion steering unit  64 . A second sliding member  93  slides on the rod  88  and is sandwiched between springs  92   a  and  92   b  which are retained between locks  91   a  and  91   b . The second sliding member  93  may thus slide on the rod  88 , but is pushed to a center position between the locks  91   a  and  91   b  by the springs  92   a  and  92   b . The inner Morse cable  70  is fixed to the second sliding member  93  and translates with the second sliding member  93 . The inner Morse cable  70  further slides through the guide  90   b  and second locks  95   a  and  95   b  are attached to the inner Morse cable  70  on each side of the guide  90   b  to limit the translation of the inner Morse cable  70  through the guide  90   b  in either direction. The Morse cable  74  is held by a first guide  90   a  attached to the rack and pinion steering unit  64 . 
     Initial translation of the steering arms  66  along arrows A1 and A2 is shown in  FIG. 16B . The translation of the steering arms  66  results in a similar translation along arrow A3 of the rod  88 . The springs  92   a  and  92   b  hold the second sliding member  93  centered between the locks  91   a  and  91   b , and the translation of the rod  88  causes the second sliding member  93  and inner Morse cable  70  to translate along arrow A6. Turning the steering wheel thus causes both turning of the front wheel for land steering and turning of the jet drive  18  (see  FIG. 14 ). 
     Full motion of the steering arm  66  is shown in  FIG. 16C . The second sliding member  93  is prevented by stops  95   a  and  95   b  from further translation past the translation shown in  FIG. 16B , and the spring  84  is compressed allowing the rod  88  to slide through the second sliding member  93 , and there is no additional translation by the inner Morse cable  70  past the translation shown in  FIG. 16B . Thus full motion of the jet drive  18  is obtained during a first translation of the steering arm  66 . 
     While the spring and sliding members of the third embodiment of a land and water steering unit  60   c  are described above at the rack and pinion steering unit end of the Morse cable  74 , a similar apparatus may reside at the jet drive  18  to provide the same result. 
     A significant advantage of the second embodiment of a land and water steering unit  60   b  is that in the centered position, the slot  82  and the spring  84  are perpendicular to the rod  88 . While the third embodiment of a land and water steering unit  60   c  provides a somewhat more simple and intuitive design, the springs  92   a  and  92   b , and the sliding direction of the sliding of the second sliding member  93  are aligned with the rod  88 . As a result, the second sliding member  93  may not hold the jet drive  18  in a centered position at high speed straight running when water impacts the sides of the jet drive  18 , i.e., water forces on the jet drive  18  may be sufficient to compress the springs  92   a  and/or  92   b  and somewhat turn the jet drive  18 . Because neither the spring  84  nor the slot  82  of the second embodiment of a land and water steering unit  60   b  are aligned with the rod  88  when the steering is centered, the jet drive  18  is better held when in the center position. 
     The amphibious vehicle  10  is shown in-water with a water line  106  above the lower edge of the door  104  is shown in  FIG. 17A , and an interior side wall  100  according to the present invention for allowing the doors to open while in the water is shown in  FIG. 17B . The interior side wall  100  is a height H WL  above the water line  106 . The height H WL  is preferably at least three inches and more preferably between four and six inches, and may vary due to vehicle loading. The combination of the running boards  21   a  and  21   b  and the interior side walls  100  allow the doors to be opened in-water, and, for example, a skier, to simply step onto either running board, and into the interior  102  of the amphibious vehicle  10 . Further, because the interior side wall  100  prevents entry of water into the amphibious car  10  in normal operation, (i.e., not in overly rough water), the doors  104  do not require sealing. 
     While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.