Abstract:
The present invention relates to a floatable vessel lift comprising: at least two pontoon chambers, where each of the at least two pontoon chambers includes a top housing and a base. The pontoon&#39;s top housing has an arcuate longitudinal surface and the base side is substantially flat. Support members horizontally join the at least two pontoon chambers to support a vessel during the lifting process. A user varies the submersion of the vessel lift during use by using a single air infusion device that introduces an air flow into the at least two pontoon chambers simultaneously.

Description:
BACKGROUND OF INVENTION 
   1. Field of the Invention 
   The present invention relates to a floating device for lifting a vessel such as a motor boat typically sized from 19 feet to 39 feet from a body of water when the vessel is not in use, providing dry storage. 
   2. Description of Related Art 
   Many docking techniques are available to boat users for boat removal and insertion into a body of water. One method involves the tying of the boat to a dock and implementing the use of a hoist lift system to remove and insert the subject boat. Usually, these hoist systems require the use of a davit, pulleys, cables and winches in various and normally complex configurations. The hoist lift systems usually include the use of a permanent dry dock in conjunction with the hoist system. Accordingly, the hoist systems normally lack any portability. Hoist systems can also be costly to install and maintain and a user normally needs to constantly monitor the height of the boat if left hoisted to adjust to the changing water levels. Davits are permanent and interfere with other uses of the dock. 
   An alternative to the mechanical hoist type lift would be the use of pontoons that may surround and support the vessel above the water while the pontoons are in water. Pontoons have the ability to automatically adjust to changes in the water level; however, pontoons may not provide the stability needed to support the vessel absent the use of extensive mechanical connections to the dock. The pontoons may sink and rise with water level, however, most pontoons for boatlifting are expensive and fail to provide independent even stable support for the subject vessel. 
   U.S. Pat. No. 5,860,379 to Moody (Moody) relates to an inflatable floating boatlift device that includes main air chambers and a network of hoses and valves connected to a blower that controls the inflation and deflation of each main chamber. The boatlift of Moody may provide a device to lift a vessel, however, the device requires a complex system of hoses and ropes for attachment to a dock. 
   U.S. Pat. No. 5,131,342 to Sackett (Sackett) relates to a boatlift including two pontoon chambers engaged to a boat hull engaging member by a lifting member connected there between. The boatlift of Sackett includes lifting members that are adapted to raise and lower the boat hull-engaging member with respect to the pontoon chambers where the pontoon chambers are adapted to buoyantly support both the boat hull engaging member and the lifting member. The floatation device of Sackett may lack sufficient stability to function according to the user&#39;s needs. 
   U.S. Pat. No. 5,002,000 to Rutter (Rutter) relates to a boatlift and leveler where the boatlift consists of a cradle supported by at least two pontoons laterally disposed beneath and fixed to the cradle. The pontoons of Rutter have a water vent through their rear lower surface and an air vent through their forward upper surface so that the rear portions of the pontoons and cradle will tend to be more submerged that the forward portions. The pontoons of Rutter require the use of additional mechanical equipment in order to function in an appropriate manner. 
   Accordingly a need exists to provide a mobile, low cost and efficient method of boatlifting. A need also exists to provide a boatlifting device that provides a stable, even and yet uncomplicated method of boatlifting. 
   SUMMARY OF INVENTION 
   The present invention addresses some of the shortcomings of the prior art by providing a stable, portable and floatable vessel lift for dry vessel storage. The most sinkable vessels are motor boats from 20 feet to around 40 feet. The present invention utilizes rigid dynamically floatable pontoon chambers, which enable the boat lift to float evenly during use. Since the present invention floats, water transport is feasible. Furthermore, the present invention does not require the use of extensive cables or hoists during operation. The pontoon chambers used with a low pressure air supply and valve allow the user to vary the depth of the lift&#39;s submersion evenly. Once the user maneuvers the lift completely level under the subject vessel, the user increases the air volume within the pontoon chambers in order to cause the lift and the vessel to immerge out of the body of water evenly. 
   The present invention relates to a floatable vessel lift comprising: at least two pontoon chambers, where each of the at least two pontoon chambers includes an upper housing and a base, where the upper housing has an arcuate longitudinal surface and the base side is substantially flat; at least two vessel support members, where the least two support members horizontally join the at least two pontoon chambers; and an air infusion device and air control valve where said air infusion device provides a controllable air supply to introduce an air flow into the at least two pontoon chambers to change ballast evenly. 
   The present invention also relates to a method of lifting a vessel out of the water for dry storage comprising the steps of: placing a vessel lift into a body of water; submerging the vessel lift and changing the water line relative to two vessel supports attached to said pontoons and allowing the influx of water into at least two pontoons having upper arcuate shaped air chambers; positioning a vessel above said vessel supports between at least two guides, where said at least two guides extend vertically from the vessel lift; infusioning air into the at least two pontoon chambers simultaneously; controlling the elevation evenly of the vessel lift by controlling the air flow into the pontoon chambers and increasing the buoyancy of the lift evenly until the vessel is supported above the water. 
   In accordance with these and other objects which will become apparent hereinafter, the instant invention will now be described with particular reference to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  shows a perspective view of the present invention. 
       FIG. 2A  shows a bottom plan view of the interior of a pontoon housing top. 
       FIG. 2B  shows a top plan view of the interior of a pontoon base. 
       FIG. 2C  shows a bottom perspective view of the floatation lift according to the present invention. 
       FIG. 3A  shows a front elevational view of a bow support member according to the present invention. 
       FIG. 3B  shows a bottom plan view of the bottom of the boat lift according to the present invention. 
       FIG. 4  is a side elevational view in cross section of one pontoon. 
   

   DETAILED DESCRIPTION 
   The present invention shown in  FIG. 1  relates to a floatable vessel lift that provides a stable and portable device to lift a vessel evenly in a body of water. The floatable vessel lift  10  enables the user to lift a vessel evenly from the water for dry storage on at least two vessel support cross members  40  and  42  adjoined to floatable parallel pontoon chambers  25  and  27 . The pontoon chambers  25  and  27  and vessel support members  40  and  42  are substantially submerged while the subject vessel (not shown) is positioned over the support cross members  40  and  42  in a longitudinally balanced and laterally symmetrically balanced position. In order to create the desired buoyancy or lift, the user inserts a single source of air into pipe  52  under pressure into the rigid air impermeable pontoon chambers causing the displacement of water within the pontoon chambers through apertures in the bottom of each pontoon chamber. As the volume of air increases in the pontoon chambers  25  and  27  and the volume of water decreases, the buoyancy or lift, and consequently, the subject vessel rises upwardly relative to the body of water evenly. Due to the arcuate configuration of the top surface of pontoon chambers  25  and  27  and implementation of buoyant stabilizing devices mounted inside each pontoon, the present invention provides a stable, evenly maintainable dynamic floatable vessel lift at all stages. 
     FIG. 1  shows an exemplary embodiment of a floatable boatlift  10  according to the present invention. The floatable vessel lift  10  includes at least two parallel pontoon chambers, a first pontoon chamber  25  and a second pontoon chamber  27 . The pontoon chambers  25  and  27  provide a system for the boat lift  10  to (adjustably) maintain buoyancy evenly floating in the water. The pontoon chambers  25  and  27  include rigid bases  21  and  23  and air impermeable top housings  20  and  21 . The pontoon tops  20  and  22  are arcuately shaped along the top longitudinal surfaces  25   a  and  27   a  and substantially flat along the bases  21  and  23 . The pontoon housings  25  and  27  have advantageously arcuate top surfaces  25   a  and  27   a  that enable the floatable lift  10  to function with an even lateral and longitudinal stability and superior control of buoyancy with internal water variation. The free surface effect of water inside each pontoon is significantly reduced by the arcuate shape. The pontoon top housings  20  and  22  are permanently sealed and attached to the pontoon bases  21  and  23 . The pontoon chambers  25  and  27  provide a stable buoyancy platform adjustable for supporting a vessel and floatable lift  10  evenly while in operation. The pontoon chambers  25  and  27  are filled with water and air. The volume of water (and volume of air) can be varied in order to vary the depth of submersion of the floatation lift  10  to raise (or lower) a supported vessel above the water line. 
   Stabilization members  30   a  through  30   d  and  32   a  and  32   b  ( FIGS. 2A and 2B ) are air tight sealed void tubes mounted in base  21 . Stabilization members  32   a  and  32   b  are lodged within the pontoon top housings  20  as shown in FIG.  2 A. Referring to  FIG. 2B , an embodiment of the base  21  is shown that includes stabilization members  30   a ,  30   b ,  30   c  and  30   d . During use, the stabilization members  30   a ,  30   b ,  30   c  and  30   d  provide additional buoyancy within the pontoon chambers  25  and  27  and provide a system for stabilizing the lift  10  during use. Each base  21 ,  23  includes stabilization members  30   a  through  30   d  that provide sealed tubes with air to increase the stability of the lift  10 . The stabilization members  30   a  through  30   d  remain suspended and fixed within the respective pontoon chambers  25  and  27  while the chambers are partially filled with water and submerged evenly in the respective body of water. The four stabilization members  30   a  through  30   d  and cross members  32   a ,  32   b  advantageously increase the overall stability of the lift  10  during all operational modes. 
   While the floatable lift  10  floats in the water, the buoyancy or water level of the lift can be varied simultaneously to each pontoon together in order to lower or raise the height of the floatable lift  10  above the water line by controlled air under pressure and a control air valve. Allowing ambient water to enter the pontoon chambers  25  and  27  by changing the air pressure internally causes the floatable lift  10  to lower and submerge evenly deeper into the water. Conversely, air under pressure may be supplied into each chamber by a single source of air together that consequently causes the internal water to flow out of the chambers  25  and  27  evenly and thus raise the level of submersion of the floatation lift  10  evenly.  FIG. 2C  shows the pontoon base water transfer openings  32  and  34  on the under side of the lift  10 . The base openings  32  and  34  enable the flow of water in and out of the pontoon chambers  25  and  27  based on the air pressure inside each pontoon. 
   As shown in  FIG. 2C , the floatation lift  10  also includes two boat or vessel support members  40 ,  42 . The support members  40 ,  42  are fixably laterally attached to both pontoon bases  21 ,  23 . The vessel support members  40 ,  42  structurally connect the pontoons  25  and  27  and engage and vertically support a subject vessel (not shown) the ambient water during operation. 
   Initially, the boat lift  10  is floating in a body of water such as a lake, ocean or river. The desired level of submergence may then be adjusted accordingly by changing the water level within the pontoon chambers  25  and  27  to increase or decrease the degree of submergence by controlling the air pressure in the pontoon chambers. The water levels within the pontoon chambers are increased simultaneously in order to increase the submergence of the floatation lift  10 . The substantially submerged floatation lift  10  may therefore readily receive a subject vessel that may be positionably weight balanced above the support members  40 ,  42 . The support members  40 ,  42  may be configured to support a bow portion, bow support member  42  and a stern portion, stern support member  40 , of the vessel. Moveable thin pole guides  201 ,  203 ,  211  and  213  ( FIG. 1 ) are rotatably mounted on the inner surface of support members  40  and  42 . The pole guides are vertical while the lift  10  is submerged and provides the user in a boat or vessel with a visible line up guide for directing a vessel over and onto the lift  10  to find a balance location. Once the user has positioned and secured the subject vessel over the support members  40  and  42 , the user may then turn on an air supply such as a blower or fan  54  to provide air under pressure through air control valve  58  into the pontoon chambers  25  and  27  through a single source of air  52 . The flow of air under low pressure into the pontoon chambers  25  and  27  causes the displacement of water within the pontoon chambers  25  and  27  to be forced out the bottom apertures  32  and  34  and consequently increase the floatation or decrease the submergence level of the floatation lift  10 . The decreased submergence level of the floatation lift  10  lifts the vessel from the water evenly and places the floatation lift  10  in the lift mode. Air under pressure is trapped in the pontoons by closing air control valve  58  during the lift mode. While in the lift mode, the vessel rests out of water upon the support members  40  and  42 . The pole guides  201 ,  203 ,  211  and  213  may be manually rotated into a horizontal stored position. The floatation lift  10  allows a user to maneuver the raised vessel by the floatable lift  10 . Furthermore, the user may store the subject vessel dry on the floatation lift  10  and easily insert the vessel back into the water when desired. 
   A single source of air under pressure comes from blower  54  and electric power source  56 , through air infusion tubing  52  shown in  FIGS. 3A and 3B . A single air source tube  52  is connected to an air supply  54  under pressure which could be low (2 pounds above atmosphere). The tubing  52  extends above the top of the port (or starboard) side pontoon chamber  25  for accessibility by user. The single tube  52  travels downward on the inside face of the pontoon chamber  25  (or  27 ) and connects into a T shaped pipe member  52   c  having tubes  52   a  and  52   b  that proceed into the pontoon chamber bases  23  and  21  respectively at the bottom sides. The air infusion tubing  52  provides a pathway for forcing air under pressure into each chamber  25  and  27  simultaneously. The air infusion tubing  52  splits into the T shaped pipe member  52   c  on the under side of the bow support member  42 . The air infusion tubes  52   a  and  52   b  extend vertically into the pontoon chambers  25  and  27  through the bottom of each respective pontoon base  21  and  23  and have openings near the arcuate top surfaces (inside) of the pontoons. The infusion of air under pressure displaces water within the pontoon chambers  25  and  27  and consequently causes the floatation lift  10  to be raised relative to the water level. After the vessel is in place over the lift  10  and between guides  201 ,  203 ,  211  and  213 , then the user connects an air supply  54  onto the receiving end of the air infusion tube  52 . Air from the pump or fan  54  travels through the tube  52  at an acceptable rate (approximately 130 CFM) and pressure in order to cause the displacement of water within the pontoon chambers  25  and  27 . As the user infuses the pontoon chambers  25  and  27  with air, the floatation lift  10  lifts with the subject boat resting upon the support members  40 ,  42 . Once the boat is upon the lift  10 , the user may manipulate, move or simply dock the lift  10  with the boat resting on the support member  40  and  42  above the water line so that the vessel is dry. Guides  201 ,  203 ,  211 ,  213  collapse to a horizontal resting position while the lift  10  and subject boat immerge from the water. The air infusion tube  52  may be sealed by control valve  58  in order to maintain a floating position for the lift  10 . The air under pressure in each pontoon is maintained by the control valve  58 . 
   The system is especially suited for motor boats from 20 feet to 39 feet, inboard or outboard having conventional drafts. To reduce the water line to re-float a supported vessel, the control valve is opened to allow ambient water into the pontoons reducing buoyancy. 
   The instant invention has been shown and described herein in what is considered to be the most practical and preferred embodiment. It is recognized, however, that departures may be made therefrom within the scope of the invention and that obvious modifications will occur to a person skilled in the art.