Abstract:
A boat capable of having a snowmobile securely mounted on its hull and steerable by the snowmobile&#39;s steering mechanism. The boat includes a bow, an aft, a port side, a starboard side, and a mid-ship. The hull of the boat includes a top and a bottom, wherein the bottom of the hull includes under-hull skis with tips and tails, and the bottom of the hull further includes a bow step positioned proximate to the tips of the under-hull skis. The boat also includes: a snowmobile opening including a cutaway of the hull extending into the hull from the aft and disposed halfway between the port and starboard sides; a transom disposed at the aft; and a boat steering mechanism including two boat ski attachment mechanisms on the port and starboard sides of the boat and two snowmobile ski attachment mechanisms on the port and starboard sides.

Description:
CLAIM OF PRIORITY 
     This application claims the benefit of priority of U.S. Provisional Patent Application Ser. No. 61/447,075, filed on Feb. 27, 2011. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to amphibious vehicles, and in particular, to an improved combination snowmobile and boat that is adapted for use in variable cold water and ice conditions such as found in water rescue operations. 
     BACKGROUND 
     In places where bodies of water at least partially freeze over during certain times of the year, there is often a need to travel across the frozen water. In some cases, this may be for emergency situations, such as where someone has fallen through the ice and must be reached for rescue. In others, it may be that one&#39;s home is on an island in the middle of a frozen lake. A snowmobile can be used to travel over solid ice, but it is rare that one can traverse a frozen body of water with complete confidence that the entire body of water is consistently solidly frozen. The rider, therefore, takes the risk that the snowmobile and rider may fall through thin ice at any time. A boat, on the other hand, may be able to move through water and break through thin ice, but will have little utility on solid ice. Therefore, there is a need for a vehicle that allows a rider to travel both over water and over solid ice. 
     Some progress has been made toward the development of such a vehicle and a number of patents disclose the conversion of conventional snowmobiles into aquatic vehicles. For example, U.S. Pat. No. 3,521,595 discloses the conversion of a conventional snowmobile into an aquatic vehicle for travel on water. This conversion involves the replacement of the steerable ground engaging snow skis with a buoyant supporting and steering arrangement that includes pontoons attached to the snowmobile body in the mounting arrangement coupled to the steering linkage of the snowmobile. The pontoons are disposed relative to the engine driven endless cleat track extending lengthwise under the body such that the track functions in the water as the propulsion means. Although this invention discloses the conversion of a snowmobile into an aquatic vehicle, it has significant disadvantages. First, the invention requires the removal of the snow skis in favor of pontoons. Such removal may be difficult and may make it difficult or impossible to replace the snow skis so that the snowmobile may eventually be used as an ordinary snowmobile again. Moreover, once converted, the only seating and storage space on the aquatic vehicle is on the snowmobile, which could make rescue operations difficult. Most importantly, the rudder used to steer this vehicle extends below the bottom surface of the pontoons, which prevents the vehicle from effectively travelling on snow and ice once it has been converted. 
     U.S. Pat. No. 4,893,692 discloses a floatable snowmobile made up of a one-piece molded plastic body. The body includes a rigid skin forming a shell defining an enclosed cavity in which there is provided an expanded closed-cell foam core of water-buoyant material. Floating skis are constructed as pontoons of similar construction to the body and replace the conventional snowmobile skis such that the whole snowmobile can float with a portion thereof out of the water so as to support a rider clear of the water in the event the snowmobile falls through ice. Although this invention also discloses a snowmobile that will not sink, it also has its disadvantages. Given its floatable construction, it is not as maneuverable as a standard snowmobile and requires significant modification in order to be converted back into a conventional snowmobile. Like the invention disclosed in U.S. Pat. No. 3,521,595, there is no seating or storage on the vehicle other than the seating and storage provided by the snowmobile, which could make rescue operations difficult. Further, and more importantly, there is no ability to effectively steer the vehicle when it is submerged in water. 
     Finally, U.S. Pat. No. 6,595,812 discloses an amphibious vehicle for traversing a body of water or solid terrain, such as a layer of ice floating atop a body of water. The vehicle includes a floatable boat hull having an elongate aperture therethrough, and a snowmobile for traveling over the solid terrain received in the opening and sealed in water impervious relation to the hull. The snowmobile includes an endless drive track, which supports the hull in spaced relation when travelling over solid terrain being and which rearwardly propels water to forwardly propel the vehicle through the water. A pair of skis supports the front of the hull in spaced relation with the solid terrain being traversed and each ski includes upturned forward ends mounting upstanding rudders for steering the vehicle as it traverses a body of water. The hull includes upwardly extending, downwardly opening pockets for receiving the front upturned ends of the skis and stabilizing arms, which are coupled between the frame and the skis. Upwardly inclined guides are provided on the underside of the hull for upwardly guiding the skis out of the water onto the ice floating on the water as the vehicle exits the water and moves onto the ice. 
     Although this vehicle has more room for storage and seating, it too has significant disadvantages. First, although the upstanding rudders allow the boat to be effectively steered once it is in water, the use of these specialized skis requires the original snowmobile skis to be removed and replaced. Second, the hard rowboat-like sides of the hull make it difficult for rescue people to lift people to be rescued into the craft, and could easily result in swamping or sinking of the vehicle. Third, the design of the bow is susceptible to a buildup of ice and snow, which could make it difficult for the craft to move up and out of the water and onto solid ice. Finally, this vehicle is solely an amphibious vehicle, which cannot be separated into a snowmobile and a boat. 
     Therefore there is a need for an amphibious vehicle that has sufficient seating and storage for rescue operations; that may be separated into an operational snowmobile and an operational boat; that is steerable both on ice and in water; that is designed to easily haul passengers from the water onto the vehicle; that does not require the removal and replacement of the snowmobile&#39;s skis in order for it to be effectively operated; and that has a hull that is not susceptible to ice and snow buildup. 
     SUMMARY OF THE INVENTION 
     The present invention includes a boat and a combination of a boat and a snowmobile. 
     In its most basic form, the present invention is a boat having a bow, an aft portion, a port side, and a starboard side. This basic form is embodied in two main versions of the present invention. The first version is described in detail below. As the second version includes many similar features to the first version, only those features that are dissimilar will be discussed in detail, and all other features should be considered to be similar to the first version. 
     In the first version of the present invention, a generally U-shaped inflatable tube is disposed around the port side, the bow, and the starboard side and provides buoyancy to the boat. A substantially rigid hull is attached to the inflatable tube and forms a platform upon which a snowmobile may be mounted. The hull includes a hull bow, a hull aft portion, a hull port side, and a hull starboard side. The hull bow, hull port side and hull starboard side extend at least partially under, and are attached to, the inflatable tube in a manner that prevents water from penetrating the joint formed therebetween. A snowmobile opening is disposed through the hull and includes an aft end and a midship end. A tubular aft structure is disposed at the aft of the top of the hull and a tubular bow structure is disposed between the aft and the bow of the boat on the top of the hull. The tubular aft structure and tubular bow structure are positioned and dimensioned to secure a snowmobile to the hull. Two steering pods are located on either side of the tubular bow structure at a location proximate to a location of each of the snowmobile skis. Each steering pod includes a steering pod cavity on the bottom of the hull that is formed by the steering pods. Two under-hull skis are disposed between the starboard side and the port side of the boat on the bottom of the hull and two boat ski attachment mechanisms attach the two under-hull skis to the bottom of the hull at the steering pod cavities. Two boat steering mechanisms extend through the steering pods and control the motion of the two under-hull skis. Each boat steering mechanism includes a first end in mechanical communication with one of the two boat attachment mechanisms in the steering pod cavities. Finally, two snowmobile ski attachment mechanisms attach to the second ends of the two boat steering mechanisms. The snowmobile ski attachment mechanisms are adapted to attach to the snowmobile skis such that steering of the snowmobile skis in a conventional manner causes the under-hull skis to move in a desired direction. 
     The inflatable tube of the first version of the present invention is preferably a durable synthetic rubber tube, such as those usually used with Hypalon-type boats. The inflatable tube preferably has three connected, but independently inflated, sections to maintain flotation even if one is compromised and each section preferably has its own inflation valve. The inflatable tube is preferably attached to the hull with cemented strips both on the top and on the bottom. A transom frame is preferably permanently attached to the inflatable tube. The inflatable tube preferably also includes lifting handles and other accessories for rescue operations cemented to it. 
     The hull is preferably manufactured of fiberglass and is designed to have a tunnel type shape, with the hull port and starboard sides on either side of a preferably raised area that includes the snowmobile opening. The snowmobile opening is a cutout in the hull sized and dimensioned to accept a snowmobile track. The tunnel hull design improves water flow to the snowmobile endless drive track while reducing exposure to the bottom of the hull. The tunnel hull design also allows reverse thrust from the snowmobile endless drive track, allowing the boat to move in both forward and backward directions. The hull preferably extends at least partially underneath the inflatable tube to protect the inflatable tube from rough ground and/or obstructions when the boat is not on water. The hull also preferably includes a chine that is stepped to raise the inflatable tube in order to further reduce its contact with the ground and ice. 
     The tubular aft structure and tubular bow structure may be made of any metal material, including rolled steel or tubular aluminum. The preferred tubular structures are made from stainless steel tubing of approximately one inch in diameter and with a 0.090 inch wall thickness. The tubular aft structure and tubular bow structure are spaced apart to allow a snowmobile to be positioned between these structures. The tubular aft structure serves as a mount for the rear of the snowmobile and the tubular bow structure serves as a mount for the front of the snowmobile and a structural brace for the steering pods. The tubular structures are preferably affixed to metal stringers embedded in the hull allowing the front and rear of a snowmobile to be rigidly mounted to the hull of the boat. 
     In a preferred embodiment, the tubular aft structure includes a three-sided cross section and two vertical braces. The first two sides of the three-sided cross section come up from the hull and the third side connects the first two. The first two sides include an outer sleeve so that they can telescope to different lengths within the outer sleeve. This adjustment allows for better securing of snowmobiles of different sizes; particularly snowmobiles of different heights. Once the desired height is achieved, an adjustment mechanism locks the first two sides in place. It is preferred that the adjustment mechanism for each side be a bolt that is secured through the side to secure it at the desired height. However, those of ordinary skill in the art will recognize that there are several ways of securing the adjustment mechanism other than through the use of bolts and that the present invention is not so limited. The cross section also preferably includes hinges at the bottom of the first and second sides that secure the first and second sides to the hull. These hinges allow the entire cross section to fold down, preferably off the aft of the boat, so that the cross section is flat. This folding down of the entire cross section essentially opens the aft of the boat to allow for the loading and unloading of the snowmobile. Moreover, the ability of the cross section to move fore and aft, even when not completely folded down, allows for better securing of snowmobiles of different sizes; particularly those of different lengths. 
     The vertical braces of the tubular aft structure intersect with the first two sides of the three-sided cross section at one end and are secured to the hull. The vertical braces are parallel to the hull starboard and port sides. The vertical braces also preferably have outer sleeves and adjustment mechanisms so that their length may also be adjusted and secured, especially to conform with the extra length necessary to allow for the cross section to be folded flat, as discussed above. Again like the first two sides of the cross section, the ends of the vertical braces that are attached to the hull are attached via hinges so that the vertical braces can fold down and/or adjust with the cross section. 
     It is preferred that the tubular aft structure also include a cross brace and two lateral braces for additional support for the tubular aft structure. The cross brace is preferably a brace spanning between the first and second sides of the three-sided cross section and is disposed below and parallel to the third side of the cross section. The two lateral braces extend out from the cross section coplanar with the plane of the cross section. One end of each lateral brace is attached to an outer sleeve of one of the first and second sides of the cross section. The other end of the lateral brace is attached to the hull with a hinge so that the lateral braces may fold down and/or adjust with the cross section. 
     In some embodiments, the tubular aft structure also serves as a transom. In the preferred embodiment, however, the boat also includes a permanent transom framework that is attached to both the hull and the inflatable tube and is independent from the aft tubular structure. In such embodiments, a center transom is preferably completed and made water-tight by a center transom insert to be installed after the snowmobile is in place. The center transom insert preferably has a rubber gasket on the bottom and both sides, and is secured in place with toggle mechanisms. 
     It is also preferred that the third side of the cross section of the tubular aft structure include at least one and preferably two clamp blocks and hook latches. These devices are designed to accept and secure the rear lift handle of a snowmobile to the tubular aft structure. The clamp locks are preferably bolted rigidly to the third side of the cross section and are recessed to accept the rear lift handle of the snowmobile. The hook latch is preferably either bolted into position or held by a toggle mechanism to secure the rear lift handle of the snowmobile. 
     It is preferred that the tubular bow structure also include at least one cross brace between the first two sides of the cross section and at least one cross brace between the vertical braces for additional support for the tubular bow structure. It is preferred that there be a first cross brace that is located below and parallel to the third side of the cross section and a second cross brace that is located below the first cross brace and diagonally spans the distance between the first two sides of the cross section. It is also preferred that there be a third cross brace that diagonally spans the distance between the two vertical braces. 
     In the preferred embodiment, the third side of the cross section of the tubular bow structure also includes at least one and preferably two clamp blocks and hook latches. These devices are designed to accept and secure the front lift handle of a snowmobile. The clamp locks are bolted rigidly to the third side of the cross section and are recessed to accept the front lift handle of the snowmobile. As was the case with the hook latch utilized in the preferred aft structure, the hook latch is preferably either bolted into position or held by a toggle mechanism to secure the front lift handle of the snowmobile. 
     The two steering pods are preferably positioned roughly on either side of the tubular bow structure and take the form of rounded protrusions from the top of the hull. These protrusions in the top of the hull create steering pod cavities in the bottom of the hull. The boat ski attachment mechanisms that attach the two under-hull skis to the bottom of the hull are disposed in the steering cavities. In the preferred embodiment, the hull also includes a bow step positioned on the bottom of the hull at the bow that protects the tips of the under-hull skis. 
     The boat ski attachment mechanism is preferably a springed piston attached to one or more a-arms that work with bushings to allow articulation of the under-hull ski. Although this is the preferred attachment mechanism, one of ordinary skill in the art will recognize that there are several ways in which the under-hull skis may be attached to the bottom of the hull and each of these ways is contemplated as being within the scope of the present invention. The geometry of the a-arms allows the tails of the under-hull skis to travel while keeping the tips of the under-hull skis nested behind the bow step, preventing the tips from being caught on foreign objects. The a-arms are attached to vertical cylinders, which carry kingpins in sealed bearings. 
     The under-hull skis are designed to ride nearly flush with the hull and cover the steering cavity to protect the boat ski attachment mechanisms and boat steering mechanisms. The under-hull skis include a perpendicular edge that extends downward and acts as a rudder when the boat is in the water and acts as a skate blade, similar to a blade on an iceboat, when the boat is on hard ice or snow. 
     In some embodiments, Teflon “skid blocks” or a layer of another non-stick material is disposed between the top of the each ski and the hull in order to allow the skis to easily move when in contact with the hull. Under normal load, the ski geometry and bump stops prevent the ski from contacting the hull. In conditions where the ski is raised above the surface of the water or ice, when contacting bumps or ridges, it will flex in order to direct the ski on top of the obstacle. Should this flex allow the tip or tail of the ski to contact the hull, the skid block prevents damage to both hull and ski, and facilitates steering while there is contact. 
     Each of the boat steering mechanisms has two ends, one of which is in mechanical communication with one of the boat ski attachment mechanisms. In the preferred embodiment, a first steering arm is the first end of the boat steering mechanism, and this mechanical communication is in the form of the first steering arm disposed at the top of one of the kingpins of one of the boat ski attachment mechanisms. The steering arm preferably includes several holes for travel adjustment. The steering arm is connected via a first shaft with spherical bearings on each end, to a second shaft with devises on each end. The second shaft travels through the hull of the steering pod and is carried in a cylinder with wiper seals on each end, thus preventing leakage. A third shaft, also with spherical bearings on each end, is attached to the second shaft. The third shaft is connected to a second steering arm. In the preferred embodiment of the boat steering mechanism, the second end of the boat steering mechanism that is disposed on the top of the hull is this second steering arm. The second end of the boat steering mechanism, which is preferably the second arm, may be affixed to a snow ski of a snowmobile through a snowmobile ski attachment mechanism and aligned with the pivot point. 
     The snowmobile ski attachment mechanism is preferably either a saddle with toggle clamps or a clevis that attaches directly to the base of the snowmobile kingpin if the snow ski of the snowmobile is removed. If a snow ski of a snowmobile is so attached to the boat steering mechanism through the snowmobile ski attachment mechanisms, then the under-hull skis of the boat will move as directed by a snowmobile steering mechanism that controls the movement of the snow skis of the snowmobile. Although the boat steering mechanism described herein is the preferred embodiment, one of ordinary skill in the art will recognize that there are several ways in which a boat steering mechanism that spans between the under-hull skis of the boat to connect with the snow skis of the snowmobile may be arranged so as to use the steering of the snowmobile as the steering of the boat, and each of these ways is contemplated as being within the scope of the present invention. Further, in some embodiments, the skis of the snowmobile may be removed and the boat steering mechanism may be adapted to connect directly to the snowmobile steering mechanism. The function of the shaft assembly may also be achieved with a cable assembly, for example. The steering mechanism may also be attached via cable to a pivoting rudder at the rear of the boat, enhancing maneuverability in the water. When on solid ground, traveling both in forward and reverse, the rudder pivots up and simply rides on the surface. 
     In some embodiments, the boat of the present invention includes an insert so that the boat is seaworthy on its own. The insert preferably includes a backboard, a motor, a floor, a seat, and a console with a steering wheel and a throttle. The backboard covers the aft of the boat. The motor is positioned on the backboard. The floor covers the snowmobile opening. The seat is for the comfort of the driver. The console preferably includes boat controls, such as a steering wheel and throttle. 
     The second version of the present invention differs from the first version in six main respects: First, the second version of the boat of the present invention does not include an inflatable tube, and does include a railing. Second, the second version of the boat of the present invention does not include a tubular bow structure, and instead includes a hull recess designed to accept a snowmobile. Third, the second version of the boat of the present invention also does not include a tubular aft structure, and instead includes a hydraulic cylinder and mounting bar system. Fourth, the second version of the boat of the present invention has different boat ski attachment mechanisms, boat steering mechanisms, and snowmobile ski attachment mechanisms. Fifth, the second version of the boat of the present invention includes thrust plates at the boat&#39;s aft. Sixth, the second version of the boat of the present invention has a modified transom. These differences are detailed below. 
     The railing of the second version of the present invention preferably extends around three sides of the boat, excluding the aft. 
     A snowmobile disposed on top of the second version of the boat of the present invention will not be stopped at the tubular bow structure, as with the first version. Instead, an entire portion of the boat, from midship to aft is recessed so as to accept the snowmobile. The hull recess includes a hull step. The snowmobile opening, ski saddles, hydraulic cylinders with frame and arms, and aspects of the boat steering mechanism, which will be discussed in more detail below, are all included within the hull recess. The hull recess allows the snowmobile to be located very low in the hull, extending the snowmobile track as far as possible below the bottom of the hull. This maximizes track contact with the snow. 
     Like the first version of the boat of the present invention, however, the second version of the boat may include an outboard insert at its aft to make the boat seaworthy for summer use when the boat is not being used in concert with a snowmobile. The outboard insert may include a transom. The insert may also be a jet drive. When the second version of the boat of the present invention is in summer use as a boat only, the lifting arms of the mounting bar, although not the nested hydraulics cylinders, the thrust plates, and the boat steering mechanism are removed, and an insert is inserted. 
     As discussed above, the tubular aft structure is also absent in the second version of the present invention. The back of the snowmobile is held in place by a mounting bar and a transom. The preferred mounting bar includes hydraulic cylinders, lifting arms, and support arm. The lifting arms extend on three sides to connect the hydraulic cylinders on either side of the snowmobile opening. The mounting bar is designed according the individual snowmobile being mounted onto the boat. The hydraulic cylinders retract to keep the mounting bar flat during mounting of the snowmobile and extend to raise the mounting bar while the snowmobile is mounted on the boat. The preferred second version of the boat of the present invention includes a different snowmobile attachment mechanism. The preferred snowmobile ski attachment mechanism of the second version includes ski saddles disposed within the hull recess on the top of the boat. The ski saddles each include a clamp mechanism that affixes the ski to the ski saddles. The ski saddles ride via a sealed bearing on a movable mounting plate attached to the floor of the hull recess. The bearings allow the ski saddles, and therefore the snowmobile skis, to pivot. The preferred second version of the boat of the present invention also includes a slightly different boat ski attachment mechanism. The preferred boat ski attachment mechanism includes a-arms, vertical cylinders, kingpins, boot seals, and bushings. The under-hull skis are secured to the sides of aluminum steering pods, which are integral to the hull through a-arms and bushings, allowing articulation of the under-hull ski. In the second version of the boat of the present invention, the steering pods are not visible above the surface of the hull, as they are in the first version. The geometry of the a-arms allows the tails of the under-hull skis to travel while keeping the tips of the under-hull skis nested behind the bow step, preventing them from being caught on foreign objects. The a-arms are attached to vertical cylinders, which carry kingpins in sealed bearings. The kingpins are sealed to the hull with boot seals. The a-arm assemblies may be dampened with urethane bushings attached to the lower a-arms and the upper portion of the steering pods. Dampening may also be accomplished with conventional coil-over springs or shock absorbers, or with torsion bars. 
     The preferred second version of the boat of the present invention also includes a slightly different boat steering mechanism, which links the boat ski attachment mechanism and the snowmobile attachment mechanism. The preferred snowmobile ski attachment mechanism includes first and second steering arms, bearings, a shaft, a steering link, and a rudder. The first steering arm is disposed at the top of the kingpin of the boat ski attachment mechanism. The second steering arm is integral to the ski saddle of the snowmobile ski attachment mechanism. Both the first and second steering arms include several holes for travel adjustment. The first and second steering arms are connected via the shaft with spherical bearings on each end where they are attached to the kingpin and ski saddle, respectively. The steering link connects the second steering arm and the rudder. The rudder pivots up on hard surfaces and drops in the water for added directional control. The rudder is located at the aft of the boat. 
     The second version of the boat of the present invention includes thrust plates. The thrust plates are positioned in the aft end of the snowmobile opening. The thrust plates provide lateral rigidity and direct water thrust by the snowmobile track, both backward and downward. 
     Finally, the second version of the boat of the present invention includes a different transom from the first version. The transom includes a removable transom rail that gives the hull torsional rigidity while also serving as a conventional rail. Not all embodiments of the second version of the boat include a transom. 
     In its most basic form, the combination of the present invention includes the boat of the present invention, as described above, and a snowmobile. The snowmobile includes a chassis with a front and a rear, an engine, an endless driving track in mechanical and electrical communication with the engine, two snow skis attached to the front of the chassis, and at least one snowmobile steering mechanism maneuverable to control the motion of the two snow skis, in mechanical communication with the engine. The snowmobile chassis is disposed on the top of the boat hull between the tubular bow structure and the tubular aft structure, with the front of the chassis next to the tubular bow structure and the rear of the chassis next to the tubular aft structure. The endless drive track of the snowmobile is disposed within the snowmobile opening of the boat and the two snowmobile ski attachment mechanisms of the boat are attached to the two snow skis of the snowmobile such that when the snowmobile steering mechanism is maneuvered, the boat steering mechanism is similarly maneuvered. 
     To load the snowmobile onto the preferred embodiment of the first version of the boat, the center transom insert is removed and the tubular aft structure is folded all the way down. The front of the chassis of the snowmobile is then positioned against the tubular bow structure, the tubular aft structure is folded back up, and the center transom insert is fitted back into place. The tubular bow structure may be adjusted for the height of the snowmobile as described above. In preferred embodiments of the tubular bow structure and tubular aft structure that include at least one clamp block and hook latch, and preferred embodiments of the snowmobile that include front and rear lift handles, the front lift handle may be accepted and secured onto the tubular bow structure through the clamp blocks and hook latches and the rear lift handle may be accepted and secured onto the tubular aft structure, as discussed above. The tubular aft structure may be adjusted for height, and may also be adjusted fore and aft as necessary to accommodate the height and length of the snowmobile and to ensure that the snowmobile is positioned such the endless drive track of the snowmobile passes through the snowmobile opening through the hull of the boat. 
     As discussed above, when the snowmobile ski attachment mechanisms of the boat are attached to the snow skis of the snowmobile, the snowmobile steering mechanisms become connected with the boat steering mechanism so that maneuvering the snow skis of the snowmobile with the snowmobile steering mechanisms also maneuvers the under-hull skis of the boat through the boat steering mechanism. In embodiments where the snowmobile skis are removed, the boat steering mechanism attaches to the snowmobile steering mechanism and functions in a similar manner. In such embodiments, the removal of the snowmobile skis allows the boat to have a narrower hull, which is advantageous in some circumstances. 
     To load the snowmobile onto the preferred embodiment of the second version of the boat, the mounting bar is lowered flat, the thrust plates are retracted, and the snowmobile is moved into position within the recessed area in the hull of the boat. In position, the snowmobile skis are secured within the ski saddles. In this position, steering the snowmobile will also steer the boat through the boat steering mechanism. The mounting bar and thrust plates are raised to support and manipulate the back of the snowmobile. 
     Therefore it is an aspect of the present invention to provide a combination snowmobile and boat vehicle. 
     It is a further aspect of the present invention to provide a combination snowmobile and boat vehicle that has sufficient seating and storage for rescue operations. 
     It is a further aspect of the present invention to provide a combination snowmobile and boat vehicle that may be separated into an operational snowmobile and an operational boat. 
     It is a further aspect of the present invention to provide a combination snowmobile and boat vehicle that uses the steering mechanism of the snowmobile to steer the boat. 
     It is a further aspect of the present invention to provide a combination snowmobile and boat vehicle that does not require the skis of the snowmobile to be removed and/or replaced. 
     It is a further aspect of the present invention to provide a combination snowmobile and boat vehicle that is designed to easily haul passengers from the water onto the vehicle. 
     It is a further aspect of the present invention to provide a combination snowmobile and boat vehicle that has a hull that is not susceptible to ice and snow buildup 
     These aspects of the present invention are not meant to be exclusive and other features, aspects, and advantages of the present invention will be readily apparent to those of ordinary skill in the art when read in conjunction with the following description, claims, and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a perspective view of the top of the boat of the first version of the present invention. 
         FIG. 1B  is a perspective cut away view of the top of the boat of the first version of the present invention. 
         FIG. 2  is a perspective view of the bottom of the boat of the first version of the present invention. 
         FIG. 3A  is an exploded perspective view of the tubular aft structure of the boat of the first version of the present invention. 
         FIG. 3B  is an exploded perspective view of the tubular aft structure, center transom, and center transom insert of the boat of the first version present invention. 
         FIG. 4  is an exploded perspective view of the tubular bow structure of the boat of the first version of the present invention. 
         FIG. 5  is a perspective view of the boat of the first version of the present invention prepared to receive a snowmobile of the present invention. 
         FIG. 6  is a perspective view of the combination of the first version of the present invention. 
         FIG. 7  is an exploded perspective view of the steering mechanism of the combination of the first version of the present invention. 
         FIG. 8A  is an isolated perspective view of an embodiment of the snowmobile ski attachment mechanism of the boat of the present invention. 
         FIG. 8B  is an isolated perspective view of an alternative embodiment of the snowmobile ski attachment mechanism of the boat of the present invention. 
         FIG. 9  is a perspective view of a boat of the first version of the present invention with an insert. 
         FIG. 10A  is a perspective view of the top of the boat of the second version of the present invention. 
         FIG. 10B  is a perspective view of an alternate embodiment of the top of the boat of the second version of the present invention. 
         FIG. 10C  is a perspective view of an alternate embodiment of the top of the boat of the second version of the present invention. 
         FIG. 11  is a perspective view of the bottom of the boat of the second version of the present invention. 
         FIG. 12A  is an isolated perspective view of the thrust plates of the boat of the second version of the present invention in engaged position. 
         FIG. 12B  is an isolated perspective view of the thrust plates of the boat of the second version of the present invention in unengaged position. 
         FIG. 13A  is an isolated perspective view of the mounting bar of the boat of the second version of the present invention in engaged position. 
         FIG. 13B  is an isolated perspective view of the mounting bar of the boat of the second version of the present invention in unengaged position. 
         FIG. 14A  is an isolated perspective view of the mounting bar and thrust plates of the second version of the present invention in engaged position. 
         FIG. 14B  is an isolated perspective view of the mounting bar and thrust plates of the second version of the present invention in unengaged position. 
         FIG. 15A  is an exploded perspective view of the steering mechanism of the combination of the second version of the present invention. 
         FIG. 15B  is an exploded perspective view of an alternate embodiment of the steering mechanism of the combination of the second version of the present invention. 
         FIG. 16A  is a perspective view of the boat of the second version of the present invention in engaged position. 
         FIG. 16B  is a perspective view of the boat of the second version of the present invention in unengaged position. 
         FIG. 17A  is a perspective view of the boat of the second version of the present invention being used as a boat only with a jet drive insert. 
         FIG. 17B  is a perspective view of the boat of the second version of the present invention being used as a boat only with an outboard insert. 
     
    
    
     DETAILED DESCRIPTION 
     Throughout the figures, common reference numbers refer to common features of the present invention. Referring first to  FIGS. 1A ,  1 B, and  2 , the preferred embodiment of the boat  16  of the present invention is shown. 
       FIG. 1A  shows the top of the first version of boat  16 , which includes bow  18 , aft  20 , starboard side  22 , and port side  24 . U-shaped inflatable tube  26  extends around the bow  18 , starboard side  22  and port side  24  and terminates in ends  116 . Hull  28  has a top  30 , which includes raised area  110 , a hull bow  34 , hull port side  36 , and hull starboard side  38 . Snowmobile opening  40  is disposed through the raised area  110  in the top  30  of the hull  28  and includes aft end  42  and midship end  44 . Steering pod  46  extends upward from the top  30  of the hull  28  and the second end  108  of boat steering mechanism  104  is shown extending therefrom. Tubular bow structure  1  is shown extending from the top  30  of the hull  28  proximate to the hull bow  34  and tubular aft structure  7  is shown extending from the top  30  of the hull  28  proximate to the aft of the boat  16 . 
       FIG. 1B  shows the top of the first version of boat  16  with a cutaway portion that reveals the top cemented strips  25  and bottom cemented strips  27  that attach inflatable tube  26  to hull  28 . The preferred hull  28  is made of fiberglass  29  and is reinforced with metal stringers  2 . As discussed below with reference to  FIGS. 3A and 4 , tubular aft structure  7  and tubular bow structure  1  are affixed to hull  28  at sections of hull  28  that are reinforced with metal stringers  2 , as shown in  FIG. 1B . 
       FIG. 2  shows the bottom of the first version of boat  16 , which includes under-hull skis  50  with tips  52 , the bottom  32  of hull  28 , bow step  112 , and chine  114 . When the boat  16  is combined with a snowmobile, such as is shown in  FIGS. 5 and 6 , snowmobile  134  is mounted between tubular bow structure  1  and tubular aft structure  7  with endless drive track  146  positioned in snowmobile opening  40 . In such embodiments, boat steering mechanism  104  is connected to snowmobile steering mechanism  150  through steering pods  46 . This arrangement is discussed in more detail below with reference to  FIGS. 5 and 7 . The design of hull  28  provides for raised area  110 , creating a tunnel that improves water flow to endless drive track  146  while reducing exposure of bottom  32  of hull  28 . Bow step  112  protects tips  52  of under-hull skis  50  from encountering obstructions. Chine  114  is stepped to raise u-shaped inflatable tube  26  to reduce its contact with the ground and ice. 
     Now referring to  FIG. 3A , tubular aft structure  7  of the first version of boat  16  is shown. Tubular aft structure  7  is affixed to metal stringers  2 , as shown in  FIGS. 1B and 4 . Tubular aft structure  7  includes cross section  8 , two vertical braces  10 , cross brace  80 , and lateral braces  82 . Cross section  8  has first side  56 , second side  58 , and third side  60 . First side  56  and second side  58  have first ends  62  that connect with hull  28  at hinge  11 , which allows cross section  8  to fold entirely down, as well as to make minor adjustments fore and aft to accommodate snowmobiles  134  of different lengths. First side  56  and second side  58  include outer sleeves  66  and adjustment mechanisms  68 . Adjustment mechanisms  68  are preferably bolts  9 . Outer sleeves  66  and adjustment mechanisms  68  allow the lengths of first side  56  and second side  58  to be adjusted and secured. Third side  60  spans between second ends  64  of first side  56  and second side  58 . Third side  60  includes clamp blocks  12  and hook latches  13 . Clamp blocks  12  and hook latches  13  secure rear lift handle  152  of snowmobile  134 . 
     Vertical braces  10  extend fore from cross section  8 , with first ends  70  of vertical braces  10  meeting outer sleeves  66  of first side  56  and second side  58  of cross section  8 . Second ends  72  of vertical braces  10  connect with hull  28  at hinges  74 . Vertical braces  10  also include outer sleeves  76  and adjustment mechanisms  78  similar to outer sleeves  66  and adjustment mechanisms  68  of cross section  8 . Hinges  74 , outer sleeves  76 , and adjustment mechanisms  78  allow vertical braces  10  to move with cross section  8  as cross section  8  is adjusted fore or aft and/or folded down. 
     Cross brace  80  spans between first side  56  and second side  58  of cross section  8 . Lateral braces  82  extend from cross section  8  coplanar with the plane of cross section  8 . First ends  84  of lateral braces  82  are attached to outer sleeve  66  of first side  56  and second side  58  of cross section  8 . Second ends  86  of lateral braces  82  are connected to hull  28  at hinges  88 . Hinges  88  allow lateral braces  82  to move with cross section  8  as cross section  8  is adjusted fore or aft and/or folded down. 
     The rearmost section of hull  28  is ramped  14  to the stern of tubular aft structure  7  to aid in unloading snowmobile  134  and to serve as a well while water escapes through scuppers in the transom, which is a panel bolted to the rearmost portion of tubular aft structure  7  (not shown). 
     Now referring to  FIG. 3B , the preferred embodiment of the first version of boat  16  is shown, which includes tubular aft structure  7 , as well as center transom  21  and center transom insert  23 . Center transom  21  and center transom insert  23  essentially seal boat  16  once snowmobile  134  has been mounted on boat  16 . Center transom  21  is attached to both hull  28  and u-shaped inflatable tube  26 . Center transom  21  is independent from aft tubular structure  7 . Center transom is completed and made water-tight by center transom insert  23 , which is installed after snowmobile  134  is in place. Center transom insert  23  has a rubber gasket on the bottom and both sides, and is secured in place with toggle mechanisms. When snowmobile  134  is being mounted on boat  16 , center transom insert  23  is removed and replaced once snowmobile  134  is mounted. 
     Now referring to  FIG. 4 , tubular bow structure  1  of the first version of boat  16  is shown. Tubular bow structure  1  is affixed to metal stringers  2 . Tubular bow structure  1  includes cross section  3 , two vertical braces  94 , and cross braces  100 ,  102 . Cross section  3  has first side  85 , second side  87 , and third side  89 . First side  85  and second side  87  have first ends  91  that connect with hull  28 . First side  85  and second side  87  include outer sleeves  90  and adjustment mechanisms  92 . Adjustment mechanisms  92  are preferably bolts  4 . Outer sleeves  90  and adjustment mechanisms  92  allow the lengths of first side  85  and second side  87  to be adjusted and secured. Third side  89  spans between second ends  93  of first side  85  and second side  87 . Third side  89  includes clamp blocks  5  and hook latches  6 . Clamp blocks  5  and hook latches  6  secure front lift handle  154  of snowmobile  134 . 
     Vertical braces  94  extend fore from cross section  3 , with first ends  96  of vertical braces  94  meeting outer sleeves  90  of first side  85  and second side  87  of cross section  3 . Second ends  98  of vertical braces  94  connect with hull  28 . Cross braces  100  span between first side  85  and second side  87  of cross section  3 . Cross brace  102  spans between vertical braces  94 . 
     Now referring to  FIG. 5 , combination  200  of the present invention is shown, including snowmobile  134  about to be loaded onto the first version of boat  16 . Tubular aft structure  7  is folded flat for loading snowmobile  134  onto boat  16 . Snowmobile  134  includes chassis  138  with front  140  and rear  142 , endless drive track  146 , snow skis  148 , snowmobile steering mechanism  150 , rear lift handle  152 , front lift handle  154  (not shown, but understood to be disposed on front  140  of chassis  138 , roughly opposite from rear lift handle  152 ), and engine  144  (not shown, but understood to be disposed within chassis  138 ). Although snowmobile steering mechanism  150  indicates the handles of snowmobile  134 , it is understood that snowmobile steering mechanism  150  includes other parts that are not visible in  FIG. 5 , and connect the motion of the handles with the motion of snow skis  148 . 
     Now referring to  FIG. 6 , combination  200  is shown with snowmobile  134  loaded on the first version of boat  16 . Tubular aft structure  7  has been folded up again to secure rear  142  of chassis  138 . Although clamp blocks  12  and hook latches  13  are not included in this embodiment of tubular aft structure  7 , it is visible that rear lift handle  152  is positioned proximate to third side  60  of cross section  8  where clamp blocks  12  and hook latches  13  would accept and secure rear lift handle  152  in a preferred embodiment. Although not apparent in  FIG. 6 , snowmobile ski attachment mechanism  136  has been attached to snow skis  148  so that snowmobile steering mechanism  150  and boat steering mechanism  104  are connected, as discussed in more detail below with reference to  FIG. 7 . 
     Now referring to  FIG. 7 , the connection between under-hull skis  50  of boat  16  and snow skis  148  of snowmobile  134  that allows steering of snowmobile  134  to steer the first version of boat  16  is shown. In  FIG. 7 , we see steering pod cavity  48  formed by steering pod  46 . Boat steering mechanisms  104  have first end  106 , which is in mechanical communication with boat ski attachment mechanism  54 , and second end  108 , which is attached to a snowmobile ski attachment mechanism  136 . Boat ski attachment mechanism  54  includes springed piston  155 , attached to one of a-arms  156  that work with bushings to allow articulation of under-hull ski  50 . A-arms  156  are attached to vertical cylinders  158 , which carry kingpins  160  in sealed bearings. 
     The mechanical communication between first end  106  and boat ski attachment mechanism  54  is in the form of first steering arm  162  disposed at the top of kingpin  160 . First steering arm  162  is first end  106  of boat steering mechanism  104 . First steering arm  162  includes several holes for travel adjustment. First steering arm  162  is connected via first shaft  164  with a spherical bearing on each end, to second shaft  166  with devises on each end. Second shaft  166  travels through hull  28  of steering pod  46  and is carried in cylinder  168  with wiper seals on each end, thus preventing leakage. Third shaft  170 , also with spherical bearings on each end, is attached to second shaft  166 . Third shaft  170  is connected to second steering arm  172 . Second steering arm  172  is second end  108  of boat steering mechanism  104 . Second steering arm  172  is affixed to snow ski  148  through snowmobile ski attachment mechanism  136  and aligned with the pivot point. As shown in  FIG. 7 , snowmobile ski attachment mechanism  136  is a saddle with toggles  174 , also shown isolated in  FIG. 8A . In some embodiments, where snow ski  148  is removed, snowmobile attachment mechanism  136  is clevis  176 , as shown isolated in  FIG. 8B . In such embodiments, clevis  176  is attached directly to the base of a snowmobile kingpin. When snow ski  148  of snowmobile  134  is attached as shown in  FIG. 7  to boat steering mechanism  104  through snowmobile ski attachment mechanism  136 , under-hull skis  50  of boat  16  will move as directed by snowmobile steering mechanism  150  that controls the movement of snow skis  148  of snowmobile  134 . Although  FIG. 7  shows only one side of combination  200 , it is understood that the other side is similarly connected. 
     Now referring to  FIG. 9 , the first version of boat  16  is shown with insert  118 . Boat  16  with insert  118  may act alone as a seaworthy boat. Insert  118  includes backboard  120 , motor  122 , floor  124 , seat  126 , and console  128  with steering wheel  130  and throttle  132 . Backboard  120  covers aft  20  of boat  16 . Motor  122  is positioned on backboard  120 . Floor  124  covers snowmobile opening  40 . Seat  126  is for the comfort of the driver. Console  128  includes boat controls, such as steering wheel  130  and throttle  132 . 
     Now referring to  FIGS. 10A-10C , various embodiments of the second version of boat  16  is shown.  FIG. 10A  shows all of the features of boat  16 .  FIGS. 10B and 10C  focus on the basic shape features of boat  16 , and omit some features shown in  FIG. 10A . These omissions do not indicate a lack of necessity of the features shown in  FIG. 10A , and omitted from  FIGS. 10B and 10C . Boat  16  includes rail  201  surrounding three sides of boat  16 , and hull recess  214 , which is a recessed area down hull step  202  within hull  28  extending from approximately mid-ship to aft. Hull recess  214  allows snowmobile  134  to be located very low in hull  28 , extending snowmobile track  146  as far as possible below hull bottom  32 . This maximizes track contact with the snow. Ski saddles  204  are disposed toward the mid-ship end of hull recess  214 . Ski saddles  204  are attached to second steering arms  233 , which are connected to first steering arms  232  by shaft  234 . Second steering arms  233  are also attached to rudder  240  by steering link  216 . As detailed in  FIG. 15A and 15B , first steering arms  232  are integral to boat ski attachment mechanism  54  so that first steering arms  232  relay the motion of snow skis  148  of snowmobile  134 , held in ski saddles  204 , to under-hull skis  50 . Similarly, second steering arms  233  relay the motion of snow skis  148  to rudder  240  through steering link  216 . 
     Hull recess  214  also includes snowmobile opening  40 . In this second version of boat  16 , snowmobile opening includes thrust plates  206  toward aft end  42  of snowmobile opening  40 . Thrust plates  206  provide lateral rigidity and direct water thrust by snowmobile track  146  both backward and downward. Aft portion  20  of boat  16  also includes removable transom rail  208 , which gives hull  28  torsional rigidity while also serving as a conventional rail for safety. Not all embodiments of boat  16  include transom rail  208 . 
     Finally, hydraulic cylinders  210  are also disposed within hull recess  214 . Hydraulic cylinders  210  are housed within frame  212  affixed to hull recess floor  203 . Hydraulic cylinders  210  are part of mounting bar  207 . Mounting bar  207  includes hydraulic cylinders  210 , lifting arms  213 , and support arm  223 . Although cut away in  FIG. 10A , lifting arms  213  extend on three sides to connect hydraulic cylinders  210  on either side of snowmobile opening  40 . Mounting bars  207  are designed according the individual snowmobile  134  mounted onto boat  16 . Hydraulic cylinder  210  retract to keep mounting bar  207  flat during mounting of snowmobile  134  and extend to raise mounting bar  207  while snowmobile  134  is mounted on boat  16 . While boat  16  is being used as a boat only in the summer without snowmobile  134 , lifting arms  213 , but not hydraulic cylinders  210  or support arms  223  are removed, along with thrust plates  206  and boat steering mechanism  104 . 
     Now referring to  FIG. 11 , a perspective view of the bottom of the second version of boat  16  of the present version is shown. As in  FIG. 2 , which shows the bottom of the first version of boat  16 , hull bottom  32  includes bow step  112  to shield tips  52  of under-hull skis  50 . Tails  239  of under-hull skis  50  are also identified. Unlike  FIG. 2 , the second version of boat  16  does not include inflatable tube  26 , and does include rail  201  and thrust plates  206 . 
     Now referring to  FIGS. 12A and 12B , thrust plates  206  are shown in engaged and unengaged positions, respectively. For all features of boat  16 , “unengaged position” is the position the feature is in as snowmobile  134  is being mounted on to boat  16 . “Engaged position” is the position the feature is in while snowmobile  134  is mounted on boat  16 . This embodiment of thrust plates  206  includes retractable steps  209 . In engaged position shown in  FIG. 12A , steps  209  are extended. In unengaged position shown in  FIG. 12B , steps  209  are retracted and a third of the height of steps  209  in engaged position so that they are flat enough to allow snowmobile  134  to mount boat  16 . Thrust plates  206  shown in  FIGS. 12A and 12B  are not the only embodiments of thrust plates  206  of boat  16  of the present invention. Other embodiments, for example, are shown in  FIGS. 10A and 10C . 
     Now referring to  FIGS. 13A and 13B , mounting bars  207  are shown in engaged and unengaged positions, respectively. Mounting bars  207  consist of hydraulic cylinders  210 , lifting arm  213 , and support arm  223 . Hydraulic cylinders  210  are flat in both engaged and unengaged positions, are affixed to hull recess floor  203 , and are disposed on either side of snowmobile opening  40 . Support arms  223  are affixed on one end to hull recess floor  203  and on the other to lifting arm  213 . At either end, support arms  223  include features allowing support arms  223  to move between engaged and unengaged positions. In unengaged position shown in  FIG. 13B , mounting bar  207  is essentially flat so that snowmobile  134  will be able to slide over mounting bar  207  unimpeded. In engaged position shown in  FIG. 13B , hydraulic cylinders  210  are extended, and lifting arm and support arms  223  arm angled upward. Mounting bar  207  in engaged position both supports snowmobile  134  and holds it in position upon boat  16 . 
     Now referring to  FIGS. 14A and 14B , mounting bar  207 , thrust plates  206 , clamps  304 , cables  242 , and rear handle  236  of snowmobile  134  are shown. Although not shown, thrust plates  206  in these FIGS. include springs that force thrust plates  206  into an unengaged position. Cables  242  extend thrust plates  206  as snowmobile  134  is lifted by mounting bar  207 . Cable  242  is slack when thrust plates  206  are unengaged. Cable  242  is an exemplary method of accomplishing the thrust plate lifting. Slotted arms, for example, may replace cable  242  to accomplish the lifting. One of ordinary skill in the art will recognize that these are but two examples of several ways in which this may be accomplished. Clamps  304  secure rear handle  236  of snowmobile  134 . One end of cable  242  is attached to clamp  304 . 
     Now referring to  FIGS. 15A and 15B , exploded perspective view of two embodiments of boat steering mechanism  204  of the combination of the second version of the present invention is shown. Boat steering mechanism  104  includes boat ski attachment mechanism  54  and snowmobile ski attachment mechanism  136 . Snowmobile ski attachment mechanism  54  of the second version includes ski saddles  204  disposed within hull recess  214  on top  30  of boat  16 . Ski saddles  204  each include clamp mechanism  220  that affixes skis  148  to ski saddles  204 . Ski saddles  204  ride via a sealed bearing (not shown) on a movable mounting plate  218  attached to floor  203  of hull recess  214 . The bearings allow ski saddles  204 , and therefore snowmobile skis  148 , to pivot. 
     Boat ski attachment mechanism  54  includes a-arms  222 , vertical cylinders  224 , kingpins  226 , boot seals  228 , and bushings  230 . Under-hull skis  50  are secured to the sides of aluminum steering pods  46 , which are integral to hull  28  through a-arms  222  and bushings  230 , allowing articulation of under-hull ski  50 . In the second version of boat  16  of the present invention, steering pods  46  are not visible above top  30  of hull  28 , as they are in the first version. The geometry of a-arms  222  allows tails  239  of under-hull skis  50  to travel while keeping tips  52  of under-hull skis  50  nested behind bow step  112 , preventing them from being caught on foreign objects. A-arms  222  are attached to vertical cylinders  224 , which carry kingpins  226  in sealed bearings. Kingpins  226  are sealed to hull  28  with boot seals  228 . A-arms  222  may be dampened with urethane bushings  230  attached to the lower part of a-arms  222  and the upper portion of steering pods  46 . Dampening may also be accomplished with conventional coil-over springs or shock absorbers, or with torsion bars. 
     Snowmobile ski attachment mechanism  136  includes first and second steering arms  232 ,  233 , bearings (not shown), shaft  234 , steering link  216 , and rudder  240  (the latter two of which are shown in  FIG. 10 ). First steering arm  232  is disposed at the top of kingpin  226  of boat ski attachment mechanism  54 . Second steering arm  233  is integral to ski saddle  204 . Both first and second steering arms  232 ,  233  include several holes for travel adjustment. First and second steering arms  232 ,  233  are connected via shaft  216  with spherical bearings on each end where they are attached to kingpin  226  and ski saddle  204 , respectively. 
     Now referring to  FIGS. 16A and 16B , the combination of boat  16  with snowmobile  134  is shown in engaged and unengaged positions, respectively. In  FIG. 16A , mounting bar  207  and thrust plates  206  are raised. In  FIG. 16B , we see mounting bar  207  lying flat so as to allow snowmobile  134  to pass onto boat  16  unimpeded. Thrust plates  206  are also retracted, but are not visible in this view. 
     Now referring to  FIGS. 17A and 17B , the second version of boat  16  is shown with jet drive insert  300  and with outboard insert  302 , respectively. As discussed above, boat steering mechanism  104 , lifting arm  213 , and thrust plates  206  are removed when boat  16  is being used as a boat only and not in concert with snowmobile  134 . 
     Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions would be readily apparent to those of ordinary skill in the art. Therefore, the spirit and scope of the description should not be limited to the description of the preferred versions contained herein.