Abstract:
The present invention relates to a stationary boat lift in which a boat is able to enter and exit with little difficulty. The boat lift allows a boat to bypass various barriers in a efficient and safe manner by vertically lifting the boat out of one body of water, translating the boat horizontally over a desired barrier, and then vertically lowering the boat into a second body of water.

Description:
This application is a continuation-in-part of prior application Ser. No. 09/371,321, filed Aug. 10, 1999, now U.S. Pat. No. 6,174,106, which was a continuation of prior application Ser. No. 09/205,862, filled Dec. 4, 1998, now U.S. Pat. No. 5,947,639. This application claims the benefit of U.S. Provisional application No. 60/070,518 filed Jan. 6, 1998. application Ser. Nos. 09/371,321 09/205,862, and 60/070,518 are hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a lifting apparatus used to portage a boat. More specifically, the present invention relates to a mechanism for vertically lifting a boat out of one body of water, transferring the boat horizontally over a barrier, and then vertically lowering the boat into a second body of water. 
     Known within the prior art are devices for lifting boats out of water for such purposes as making repairs, protecting boats from dock collision caused by tidal action, and preventing damage to a boat&#39;s hull from excessive exposure to water. U.S. Pat. No. 5,184,914, describes and shows a boat lift that consists of a frame which cradles and lifts a boat from the water by the means of a hydraulic ram. The device requires a person to enter the water to secure several members of the device around the bottom of the hull. U.S. Pat. No. 5,593,247 describes a programmable boat lift control system that with the push of a button, the lift may either raise or lower the boat to a pre-programmed elevation. 
     Both of these devices are useful for lifting boats out of water, but are both limited to lifting and lowering the boat in a vertical direction which is indicative of the general state of the art in boat lifting devices. The prior art fails to teach an apparatus that can both, lift and lower a boat in a vertical direction and transfer the boat in a horizontal direction. Applicant has discovered the need to transfer boats over barriers, such as water divider walls. In many areas salt water and fresh water are separated by various types of barriers. Barriers are needed to separate fresh water from salt water due to the various types of organisms, plants and animals which can only survive in either salt or fresh water, but not both. Regardless of the need to isolate salt from fresh water, boats and other types of water vehicles still require access to and from these separate bodies of water. 
     The foregoing illustrates limitations known to exist in present boat lift apparatuses. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter. 
     SUMMARY OF THE INVENTION 
     In one aspect of the present invention, this is accomplished by providing a boat lift apparatus comprising: a moveable hoist assembly erected over a barrier separating a first body of water and a second body of water, the hoist assembly including a moveable lift frame and a load distribution subassembly connected to the lift frame, wherein the load distribution subassembly includes a pair of load distribution supports extending longitudinally and spaced laterally relative to one another and a cradle connected between the load distribution supports and capable of receiving a boat to be carried across the barrier by the apparatus; a mechanism for raising and lowering the lift frame; and a mechanism for conveying the hoist assembly between a first position over the first body of water to a second position over the second body of water. 
     After the boat has entered the lift it is positioned over a pair of slings which are placed under the boat. One sling is located near the bow or front portion of the boat while the second sling is located near the stern or rear portion of the boat. The slings are fastened to a lift frame which is lowered or raised by hydraulic power. 
     Once the boat is in a fully raised position, the boat lift translates the boat in a horizontal direction over the particular barrier. Translation of the hoist is controlled by a motor which powers a set of flanged wheels to move the boat lift back and fourth in a horizontal direction. An operator is able to easily control the functioning of the boat lift through a control panel located near or within the boat lift. 
     It is therefore an object of the present invention to provide a new and improved boat lift capable of lifting a boat in and out of water in both a vertical and horizontal direction. 
     It is a further object of the present invention to provide a boat lift which can be easily and safely operated by one or more individuals, who are operators of the boat and not require an operator full time for the boat lift. 
     It is still a further object of the present invention to provide a boat lift which allows a boat to be lifted and carried over various types of barriers. 
    
    
     The foregoing and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing figures. 
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
     FIG. 1 is a front elevational view of the boat lift apparatus of the present invention; 
     FIG. 2 is a side elevation view of the boat lift apparatus shown in FIG. 1 as the boat initially enters the boat lift apparatus. 
     FIG. 3 is a side elevation view of a first embodiment of the lift frame of the boat apparatus shown in FIG. 1; and 
     FIG. 4 is a side elevation view of a second embodiment of the lift frame of the boat apparatus shown in FIG.  1   
    
    
     DETAILED DESCRIPTION 
     In the following description of a preferred embodiment of the present invention, reference is made to the accompanying drawings which, in conjunction with this detailed description, illustrate and describe a boat lift capable of hoisting a boat out of one body of water, translating the boat in a horizontal direction over a barrier and then lowering the boat into a second body of water. Referring to FIG. 2, boat lift  10  consists of vertically moveable lift frame  24  mounted on a horizontally moveable lift frame support bed  26  which rolls on tracks  32  which are placed alongside a first body of water  18  and a second body of water  20  divided by barrier  16 . Many areas having both salt and fresh water bodies must take care not to allow the two bodies of water to mix thereby contaminating the fresh water. Various types of organisms, plants and animals can only survive in either salt water or fresh water. To accomplish this many communities construct barriers separating the two bodies of water. The down side to using barriers is that boats are prevented from freely traveling between the fresh and salt water bodies. 
     In FIG. 1, boat  12  enters boat lift  10  at either one of two ends via either first body of water  18  or second body of water  20 . Channel  14  of boat lift  10  is divided into two sections by barrier  16 . Barrier  16  is located between and divides the first and second bodies of water,  18  and  20  respectively, at approximately the middle of the channel  14  effectively creating two isolated bodies of water. 
     The vertically moveable lift frame  24  consists of two sub-frames  24   a ,  24   b , one on each side of channel  14 . As shown in FIG. 3, each lift sub-frame  24   a ,  24   b  consists of two sections, an upper platform  36  and a lower scissors platform  38 . The upper platform  36  includes a lower beam  52  attached to upper beams  56  by a plurality of fixed supports  54 . On the inner (or channel side) side of each lift sub-frame  24   a ,  24   b , a load distribution subassembly  58  is attached to the upper beams  56 . A cradle  80  is attached to the load distribution subassemblies  58  at cradle connectors  60 . Preferably one connector  60   a  is a fixed connection and the other connector  60   b  is slideable along load distribution subassembly  58 . Lift sub-frames  24   a ,  24   b  are connected to one another by transversely extending trusses  68  which span channel  14 . Trusses  68  are connected to upper beams  56 . To accommodate varying loads, ground settlement and other alignment problems, trusses  68  may be fixed to one lift sub-frame  24   a  and slidingly connected to the other lift sub-frame  24   b  to allow for movement of the tops of the lift subframes  24   a ,  24   b  towards or away from each other. To provide additional support and stiffness to the upper platform, cross supports  62  can be provided. The load distribution subassemblies  58  can be omitted and cradle  80  can be attached to other portions of upper platform  36 . 
     Preferably, cradle  80  is a pair of slings, as shown in the figures. Slings  80 , preferably, are fabricated from high strength polyester which is resistant to damage t- from abrasion and deterioration from exposure to water, particularly salt water. The slings  80  may also be fabricated materials offering similar damage resistance, such as nylon and the like. It is also possible that the cradle for carrying boat  12  may be comprised of other suitable means, including but not limited to, a heavy gauge net which may be coupled at its extremities to connectors  60   a ,  60   b . Like the slings  80 , such net may also be produced from high strength polyester or nylon. In order that the slings  80 , or alternatively a net, will readily submerge rather than float, lead weights are provided with the slings  80  arid the net. In the case of the slings  80 , the lead weights are sewn into packets provided in the slings  80 . Preferably cradle  80  is does not retain any water around the boat  12  when the boat  12  is lifted out of the water. 
     The lower scissors platform  38  consists of a lift frame support bed  26  connected to upper platform lower beam  52  by double scissors mechanisms  40 . The lift frame support bed  26  has a plurality of support legs  28  attached thereto with wheels  30  attached to axles  34 , at the lower ends thereof. The wheels  30  engage a track  32  which extends along the channel  14  on both sides of the channel  14 . The wheels  30  and track  32  permit the boat lift  10  to move horizontally along the channel  14  to transport a boat  12  over the barrier  16  from the first body of water  18  to the second body of water  20  or vice versa. A transit motor  70  is attached to a lower side of the lift frame support bed  26 . The transit motor  70  preferably drives one set of wheels  30  through a chain and sprocket (not shown). 
     The scissors mechanisms  40  each consist of two scissors legs  40   a ,  40   b , pivotally connected by scissors connector  46 . One end  42  of each scissors mechanism legs  40   a ,  40   b  is fixed to the lower scissors platform  38 . The other end  44  slides along either an upper surface of lift frame support bed  26  or a lower surface of upper platform lower beam  52 . Upper hydraulic cylinder beams  48  are provided between scissors legs  40   a ,  40   b  (See FIG.  1 ). Hydraulic cylinders are connected between the lift frame support bed  26  and the upper hydraulic cylinder beams  48 . The left side of FIG. 1 illustrates the lift frame  24  when the hydraulic cylinders  50  are retracted and the lift frame  24  is in its lower position. The left side of FIG. 1 also illustrates the left sling position (shown in FIG. 2) with the slideable sling connector  60   b . The left side of FIG. 1 shows in phantom lines the upper position of lift frame  24 . The right side of FIG. 1 illustrates the lift frame  24  when the hydraulic cylinders  50  are fully extended pressing against upper hydraulic cylinder beam  48  causing the scissors mechanisms  40  to lift the upper platform  36  to a raised or upper position. In the preferred embodiment, the upper platform raises about 7 feet. A hydraulic power source (not shown) is provided on the lift frame  24 . Retractable cords (not shown) are provided to provide electrical power and control signals to the transit motor  70  and the hydraulic power source. The intended maximum boat weight that boat lift  10  can lift is 20,000 lbs. By changing the strength and configurations of the structural members, the size of the hydraulic cylinders, higher boat weights can be accommodated. 
     Although the preferred embodiment shows a lift frame  24  which uses double scissors mechanisms  40 , other configuration of hydraulic lifting devices may be used. One example is shown in FIG. 4 where a single scissors mechanism  40  is used for each lift sub-frame  24   a ,  24   b . Another configuration could use multiple levels of lift frame support beds, each support bed being connected to the one above it by a set of hydraulic cylinders. The scissors mechanisms  40  or other lift multiplier mechanisms are preferred. 
     In use, the boat lift  10  is positioned over the first body of water  18  with the lift frame  24  in the lower position. Boat  12  is driven into channel  14  and positioned with the slings  80  about the boat  12  as shown in FIG.  2 . Because of the slideable connector  60   a , the left most sling  80  (as shown in FIG. 2) can be moved to accommodate different length boats. Hydraulic power is provided to the hydraulic cylinders  50  causing the hydraulic cylinders  50  to extend and lifting the upper platform  36 , attached slings  80  and boat  12 . Transit motor  70  is energized moving boat lift  10  from over the first body of water  28  over the barrier  16  and over the second body of water  20 . The hydraulic power is turned off and the hydraulic pressure to the hydraulic cylinders  50  is relieved allowing the hydraulic cylinders  50  to retract, thereby lowering the upper platform  36  along with slings  80  and boat  12  to its lower most position, lowering the boat  12  into the body of water  20 . The boat  12 , having successfully transited barrier  16 , can now be driven in the second body of water  20 .