Patent ID: 7210420

Claim:
A boat lift floating on a body of water, comprising: (a) a pair of laterally spaced buoyant structures adapted when installed in said body of water to establish a well therebetween; (b) a boat support frame, having a forward end and an opposing rear end, said frame being pivotally mounted to said buoyant structures at a pivot point such that a selected portion of the length of said frame is disposed rearwardly of said pivot point; (c) a vessel partially filled with liquid ballast, secured to and pivoting with said frame, the weight of said frame and vessel with ballast distributed on said pivot point in a manner which tends to cause the trailing said rear end of said frame when not having a boat mounted thereon to pivot downwardly into water confined proximate the entrance to said well, and the said forward end to pivot upwardly; (d) said boat support frame, beams, buoyant structures and vessel being arranged and constructed such that a boat may be driven onto said boat support frame by use of its own said propulsion means, lifted by said buoyant structures and positioned for storage and then drawn down by the pivoting of said frame caused by the change in distribution of weight about the pivot point resulting from the receipt of the boat and further resulting from shift in said ballast in said vessel.