Pneumatic Boat Lift with Boat-Carrying and Boat-Guiding Air Tanks

Abstract

A pontoon boat lift features tanks adjacent opposite sides thereof with upper walls slopes upwardly in a laterally outward direction. In lowered positions of the tanks, top ends of the sloped walls remain above water for visual and physical guidance of the pontoon boat into a position placing pontoons thereof between the outwardly sloped walls and over submerged portions of the lowered tanks, thereby allowing subsequent seating of the pontoons on said sloped walls during raising of the air tanks to lift the pontoons from the water. Buoyancy control for raising and lowering of the tank is effected by controlling air and water content thereof. The tanks are arranged to trap sufficient air therein to keep the lift buoyant to prevent sinking without using legs to support the boat lift on the sea, lake or river bed. The lift is adjustable in width and length for boats of varying size.

1 . A boat lift for elevating a pontoon boat out of a body of water, the boat lift comprising:
 a frame having front and rear ends spaced along a longitudinal dimension and opposite first and second sides spaced apart in a transverse dimension perpendicular to the longitudinal dimension;   a plurality of tanks mounted to the frame, including at least one first-side tank mounted to the frame adjacent the first side thereof and at least one second-side tank mounted to the frame adjacent the second side thereof, each tank comprising a shell enclosing a hollow interior, an air flow port that opens through the shell into the hollow interior, and a water port opening through the shell into the hollow interior adjacent a bottom of said hollow interior, wherein the shell of each tank has a concavely shaped upper end comprises two oppositely sloped walls positioned over the hollow interior of the shell and sloping upwardly and outwardly toward respective sides of the frame to define a channel that extends longitudinally of the frame between the sloped walls at a topside of the shell;   an air pumping mechanism connected to the air flow port of each tank and operable to convey air into the hollow interior thereof to float the tanks into raised positions situating upper ends of the outwardly sloped walls above water level; and   an air release mechanism connected to each tank and operable to release air from within the hollow interior thereof to decrease the buoyancy of the tanks for movement from the raised positions to lower positions, in which lower ends of the outwardly sloped walls and portions of the outwardly sloped walls that are found above water level in the raised positions are submerged below water level while the upper ends of the outwardly sloped walls remain above water level;   wherein the channels of the first-side tank and the second-side tank are arranged to accommodate lower portions of first and second pontoons of the pontoon boat therein with the tanks in the lower positions for subsequent elevating of the pontoon boat out of the body of water by lifting of the pontoons by the upper ends of the tanks during movement of the tanks into the raised positions.   
     
     
         2 . (canceled) 
     
     
         3 . The boat lift of  claim 1  wherein the at least one first-side tank comprises front and rear first-side tanks respectively disposed adjacent the front and rear ends of the frame, and the at least one second-side tank comprises front and rear second-side tanks respectively disposed adjacent the front and rear ends of the frame. 
     
     
         4 . (canceled) 
     
     
         5 . (canceled) 
     
     
         6 . (canceled) 
     
     
         7 . (canceled) 
     
     
         8 . (canceled) 
     
     
         9 . The boat lift of  claim 1  wherein the air release mechanism comprises one or more valves each installed in an air passage that communicates with the hollow interiors of one or more of the tanks, each valve being operable to selectively open said air passage to release air from the hollow interior of the one or more tanks, and close said air passage, to retain air within the hollow interior of the one or more tanks. 
     
     
         10 . The boat lift of  claim 9  wherein the air passage in which each valve is installed connects the air pump to the one or more tanks, and the air pumping mechanism is operable to convey air to said one or more tanks when said valve and said passage are open. 
     
     
         11 . The boat lift of  claim 9  wherein the one or more valves comprises a plurality of valves, each operable to control air flow within the hollow interior of the shell of a respective one of the tanks. 
     
     
         12 . The boat lift of  claim 11  comprising valve controls connected to the plurality of valves and operable for control thereof independently from one another. 
     
     
         13 . The boat lift of  claim 1  comprising pump controls connected to the air pumping mechanism and operable for control over air-filling of each tank independently from one another. 
     
     
         14 . The boat lift of  claim 1  wherein the frame comprises a width adjustment mechanism operable to change a width of the frame between the opposite first and second sides thereof. 
     
     
         15 . The boat lift of  claim 1  wherein the frame comprises a length adjustment mechanism operable to change a length of the frame between the front and rear ends thereof. 
     
     
         16 . The boat lift of  claim 14  wherein the width adjustment mechanism comprises at least one set of telescopically mated frame members, said frame members being slidable into, and lockable together in, different relative axial positions with one another to change an effective axial length spanned by said set. 
     
     
         17 . The boat lift of  claim 1  comprising a stop device projecting upward to an elevation above the upper ends of the tanks adjacent the front end of the frame to limit movement of the boat over the frame from the rear end when the tanks are in the lowered positions. 
     
     
         18 . The boat lift of  claim 17  wherein the stop device comprises at least one resilient bumper presenting an impact surface facing toward the rear end of the frame for contact therewith by the boat. 
     
     
         19 - 25 . (canceled)