Abstract:
A movable platform for attachment to a transom of a boat is disclosed. The movable platform includes a planar platform disposed horizontally and a planar frame coupled to an underside of the platform. The movable platform further includes at least one elongated tube coupled to the transom of the boat, wherein at least one element of the planar frame is movably disposed within the at least one elongated tube. The movable platform further includes at least one cylinder disposed horizontally, wherein a barrel of the at least one cylinder is secured to the at least one elongated tube and wherein a piston rod of the at least one cylinder is secured to the planar frame, such that the planar frame is moved horizontally when the piston rod moves within the barrel.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     INCORPORATION BY REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC 
     Not Applicable. 
     FIELD OF THE INVENTION 
     The invention disclosed broadly relates to the field of marine devices, and more particularly relates to the field of lift devices with platforms for boat transoms. 
     BACKGROUND OF THE INVENTION 
     A platform coupled to a lifting device on the transom of a boat can be used as a swimming platform, which is lowered into or close to the water line during use, or for lifting small crafts, such as a personal watercraft or a dinghy, into and out of the water. Such apparatus provide convenience to users that desire a swimming platform that can be lowered into the water for use when the boat is anchored or docked and that can be retracted out of the water when the boat is moving or in operation. Such devices are further convenient because they allow users to secure a small watercraft onto the platform, to extend the platform into the water for use of the small watercraft and then to retract the platform out of the water when use of the small watercraft is complete. Various conventional lifting devices with platforms for boat transoms are available. But conventional devices of this type are not without their drawbacks. 
     Conventional lifting devices with platforms for boat transoms normally only provide lift in the upwards or downwards directions. U.S. Pat. Nos. 4,878,450 and 5,544,606 are examples of such conventional lifting devices with platforms. Though these devices may satisfy the desire of users to lift a platform into and out of the water, they do not satisfy the desire of users to move a platform in other directions. Therefore, having only two degrees of freedom limits the versatility of conventional lifting devices with platforms. 
     Therefore, a need exists to overcome the problems with the prior art as discussed above, and particularly for a lifting device with a platform for a boat transom that provides additional degrees of freedom in its movement. 
     SUMMARY OF THE INVENTION 
     Briefly, according to an embodiment of the present invention, a movable platform for attachment to a transom of a boat is disclosed. The movable platform includes a planar platform disposed horizontally and a planar frame coupled to an underside of the platform. The movable platform further includes at least one elongated tube coupled to the transom of the boat, wherein at least one element of the planar frame is movably disposed within the at least one elongated tube. The movable platform further includes at least one cylinder disposed horizontally, wherein a barrel of the at least one cylinder is secured to the at least one elongated tube and wherein a piston rod of the at least one cylinder is secured to the planar frame, such that the planar frame is moved horizontally when the piston rod moves within the barrel. 
     In another embodiment of the present invention, a lifting device for attachment to a transom of a boat is disclosed. The lifting device includes a planar platform disposed horizontally and a planar frame coupled to an underside of the platform. The lifting device further includes at least one elongated tube coupled to the transom of the boat, wherein at least one element of the planar frame is movably disposed within the at least one elongated tube. The lifting device further includes at least one cylinder disposed horizontally, wherein a barrel of the at least one cylinder is secured to the at least one elongated tube and wherein a piston rod of the at least one cylinder is secured to the planar frame, such that the planar frame is moved horizontally when the piston rod moves within the barrel. The lifting device further includes a lift assembly coupled to the transom of the boat, wherein the lift assembly is coupled to the at least one elongated tube and wherein the lift assembly moves the at least one elongated tube in a vertical direction. 
     The foregoing and other features and advantages of the present invention will be apparent from the following more particular description of the preferred embodiments of the invention, as illustrated in the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and also the advantages of the invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings. Additionally, the left-most digit of a reference number identifies the drawing in which the reference number first appears. 
         FIG. 1  is an illustration of a top view of the lifting device when the cylinders are extended, in accordance with one embodiment of the present invention. 
         FIG. 2  is an illustration of a top view of the lifting device when the cylinders are retracted, in accordance with one embodiment of the present invention. 
         FIG. 3  is an illustration of a side view of the lifting device when the platform is raised, in accordance with one embodiment of the present invention. 
         FIG. 4  is an illustration of a side view of the lifting device while the platform is being lowered, in accordance with one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention solves problems with the prior art by providing a movable platform that provides additional degrees of freedom of movement of the platform. The apparatus of the present invention provides movement of the movable platform in the forwards and backwards directions in addition to the upwards and downwards directions. Thus, in addition to providing movement of the movable platform into and out of the water, the movable platform can also be moved towards and away from the transom of the boat. This additional degree of movement provides convenience to users that desire to move the platform away from the boat when docking a personal watercraft and to move the platform towards the boat when docking is complete. This additional degree of movement further provides convenience to users that desire assistance when docking a watercraft, such that the location of the platform may be adjusted during docking so as to accommodate the location of the watercraft in the water. 
     Furthermore, the present invention solves the problem associated with the clearance distance needed during lifting and lowering of a platform. A lifting device of this type requires that the platform be located a minimum distance from the transom of the boat during lifting and lowering of the platform so that the platform does not contact the transom or other elements of the lifting device. The present invention allows such a clearance distance to be in place during lifting and lowering of the platform while still allowing the platform to be brought closer to the transom when lifting and lowering of the platform is complete. 
       FIG. 1  is an illustration of a top view of the lifting device  100  when the cylinders  128 ,  129  are extended, in accordance with one embodiment of the present invention.  FIG. 1  shows that the lifting device  100  comprises a roughly U-shaped structure  102 . The structure  102  comprises two parallel tubes  104 ,  106  that are arranged in a horizontal direction and parallel to the major axis of the boat. Each parallel tube  104 ,  106  can have a rectangular cross-section, a circular cross-section or the like. Connecting the parallel tubes  104 ,  106  is the rigid bar  108  that is arranged in a horizontal direction and perpendicular to the major axis of the boat and the parallel tubes  104 ,  106 . 
       FIG. 1  further shows that the lifting device  100  comprises a roughly rectangular-shaped frame  110 . The frame  110  comprises two parallel bars  112 ,  114  that are arranged in a horizontal direction and parallel to the major axis of the boat. Each parallel bar  112 ,  114  can have a rectangular cross-section, a circular cross-section or the like. Connecting the parallel bars  112 ,  114  along the top ends is the rigid bar  116  that is arranged in a horizontal direction and perpendicular to the major axis of the boat and the parallel bars  112 ,  114 . Connecting the parallel bars  112 ,  114  along the bottom ends is the rigid bar  118  that is arranged in a horizontal direction and perpendicular to the major axis of the boat and the parallel bars  112 ,  114 . Rigid bar  116  is parallel to rigid bar  118 . 
     Situated on each corner of the rectangular frame  110  is a welding plate  140  on which a movable platform (not shown) is coupled. In one embodiment, portions of the movable platform are welded to the welding plates  140  of rectangular frame  110  so as to securely couple the movable platform to the rectangular frame  110 . 
     Parallel bars  112 ,  114  are movably situated within the parallel tubes  104 ,  106  such that at least a portion of the parallel bars  112 ,  114  extends out of the parallel tubes  104 ,  106  while at least a portion of the parallel bars  112 ,  114  remains within the parallel tubes  104 ,  106 . The parallel bars  112 ,  114  may slide or move within parallel tubes  104 ,  106  depending on the state of the cylinders  128 ,  129 . In one embodiment, ball bearings, wheels or other friction-eliminating devices can be disposed within the point of junction between parallel bars  112 ,  114  and parallel tubes  104 ,  106  so as to facilitate movement of the parallel bars  112 ,  114  within the parallel tubes  104 ,  106 . 
       FIG. 1  further shows cylinders  128 ,  129  that comprise barrels  120 ,  121 , respectively, and pistons  122 ,  123 , respectively. The barrels  120 ,  121  are securely coupled to the rigid bar  108  on one end. The pistons  122 ,  123  extend out of the other end of the barrels  120 ,  121 . The pistons  122 ,  123  are securely coupled on one end to the rigid bar  118 .  FIG. 1  shows the cylinders  128 ,  129  in an extended state as the pistons  122 ,  123  are shown extended outwards. As the pistons extend outwards and away from the transom  130  of the boat, the parallel bars  112 ,  114  move accordingly within the parallel tubes  104 ,  106  (which remain stationary). As such, the frame  110  is shown moved away from the transom  130  of the boat. Cylinders  128 ,  129  may be oil-based hydraulic cylinders activated via an oil line, pneumatic cylinders activated via a pump or an air line or electric cylinders activated via a power line. 
       FIG. 2  is an illustration of a top view of the lifting device  100  when the cylinders  128 ,  129  are retracted, in accordance with one embodiment of the present invention.  FIG. 2  shows the cylinders  128 ,  129  in a retracted state as the pistons  122 ,  123  are shown retracted inwards. As the pistons move inwards and toward the transom  130  of the boat, the parallel bars  112 ,  114  move accordingly within the parallel tubes  104 ,  106  (which remain stationary). As such, the frame  110  is shown moved toward the transom  130  of the boat. 
       FIG. 3  is an illustration of a side view of the lifting device  100  when the platform  302  is raised above the water line  350 , in accordance with one embodiment of the present invention.  FIG. 3  shows a platform  302  on which a fastener  301  for fastening a watercraft is situated.  FIG. 3  further shows that the lifting device  100  comprises a lifting assembly  300  that is attached to the transom  130  of a boat via a mount  304 . The lifting assembly  300  comprises a first lower arm  306  pivotally coupled to the mount  304  at pivot  312 . The first lower arm  306  is immovably coupled with second lower arm  308  via welding plate  310 . The lifting assembly  300  further comprises a first upper arm  316  pivotally coupled to the mount  304  at pivot  322 . The first upper arm  316  is immovably coupled with second upper arm  318  via welding plate  320 . 
     One end of second lower arm  308  is pivotally coupled to the box  330  at pivot  332  while one end of second upper arm  318  is pivotally coupled to the box  330  at pivot  334 . One end of vertical support  340  is pivotally coupled to the box  330  at pivot  344  while the other end of vertical support  340  is coupled to parallel tube  106 . One end of vertical support  342  is pivotally coupled to the box  330  at pivot  346  while the other end of vertical support  342  is coupled to parallel tube  106 . The frame  110  consisting of parallel bar  114  is in the retracted position (as in  FIG. 2 ) thereby placing the attached platform  302  (attached to frame  100  via welding plates  140 ) as close to the transom  130  as possible. 
       FIG. 3  further shows that the lifting assembly  300  includes a cylinder  360  consisting of a barrel  362  pivotally coupled to the mount  304  at pivot  366  and of a piston  362  pivotally coupled to the welding plate  310  at pivot  368 . In  FIG. 3 , the piston  364  is retracted and therefore the lifting assembly  300  and the platform  302  are above the water line  350 . Cylinder  360  may be an oil-based hydraulic cylinder activated via an oil line, a pneumatic cylinder activated via a pump or an air line or an electric cylinder activated via a power line. 
       FIG. 4  is an illustration of a side view of the lifting device  100  while the platform  302  is being lowered below the water line  350 , in accordance with one embodiment of the present invention. As piston  362  extends, arm  316  pivots about pivot  322  as is lowers into the water and arm  306  pivots about pivot  312  as is lowers into the water. Likewise, cylinder  360  pivots about pivot  366  as it rotates downwards. As piston  362  extends, the lower arms  306 ,  308 , as well as the upper arms  316 ,  318  begin to lower towards the water line  350 . As this occurs, the box  330  is lowered into the water as the arm  318  pivots about pivot  334  and arm  308  pivots around pivot  332 . Further, as box  330  lowers towards the water, arm  340  pivots around pivot  344  and arm  342  pivots around pivot  346 . In this matter, box  330  so as to maintain the horizontal disposition of structure  102  and, by extension, platform  302 . 
     The frame  110  consisting of parallel bar  114  is in the extended position (as in  FIG. 1 ) thereby placing the attached platform  302  (attached to frame  100  via welding plates  140 ) as far from the transom  130  as possible, so as to accommodate the distance clearance necessary during lowering of the platform  302 . 
     Although specific embodiments of the invention have been disclosed, those having ordinary skill in the art will understand that changes can be made to the specific embodiments without departing from the spirit and scope of the invention. The scope of the invention is not to be restricted, therefore, to the specific embodiments. Furthermore, it is intended that the appended claims cover any and all such applications, modifications, and embodiments within the scope of the present invention.