Boat lift

Abstract

An apparatus and method are described for lifting a boat out of water. An improved boat lift having at least one support beam upon which the weight of a boat rests, the support beams having an interior wherein components of a cable drive system are mounted, provides lifting force through operation of the cable drive system, which withdraws the support cables to within the interior of the support beams, the cables attached at one of their ends to fixed points external to the beam.

1 . A boat lift, comprising:
 multiple support beams positioned apart to support a boat;   at least one cable attached to each support beam and anchored to at least one fixed support to support the corresponding support beam;   a lift mechanism attached to each of the multiple support beams, each lift mechanism when activated causing the cable to be drawn into or around the lift mechanism to cause the support beam along with the lift mechanism to move relative to the fixed support to raise the boat.   
     
     
         2 . The boat lift of  claim 1  in which the multiple support beams each include an interior and in which the lift mechanisms are positioned within the interiors of the support beams. 
     
     
         3 . The boat lift of  claim 1  in which the lift mechanism is hydraulically operated. 
     
     
         4 . The boat lift of  claim 3  further comprising a single hydraulic pump that provides hydraulic fluid to the lift mechanisms on all of the beams. 
     
     
         5 . The boat lift of  claim 3  in which each lift mechanism includes a hydraulic cylinder and a piston. 
     
     
         6 . The boat lift of  claim 3  in which each lift mechanism includes at least two hydraulic cylinders and pistons. 
     
     
         7 . The boat lift of  claim 3  in which each lift mechanism includes two spools that rotate to draw cable onto the spools, at least one of which is powered. 
     
     
         8 . The boat lift of  claim 1  in which the beam includes at least one telescoping section for varying the length of the beam to allow the beam to span slips of different widths. 
     
     
         9 . The boat lift of  claim 1  in which each lift mechanism includes:
 a hydraulic cylinder with a piston; 
 at least two pulley blocks through which the cable is routed, one on either side of the hydraulic cylinder, so that extending the piston increases the distance between the pulley blocks to draw additional cable into or around the lift mechanism. 
 
     
     
         10 . The boat lift of  claim 9  in which each beam is tubular and in which the hydraulic cylinder and the at least two pulley blocks are positioned inside the tubular beam. 
     
     
         11 . The boat lift of  claim 10  in which one of the pulley blocks is fixed relative to the beam and the other one of the pulley blocks moves relative the beam as the piston moves in the cylinder, and further comprising a friction reducer to facilitate movement of the moving pulley block relative to the beam. 
     
     
         12 . The boat lift of  claim 11  in which the friction reducer comprises a bearing positioned on the pulley block. 
     
     
         13 . The boat lift of  claim 12  in which the friction reducer comprises a ball bearing positioned on at least four corners of the pulley block. 
     
     
         14 . The boat lift of  claim 1  further comprising a latch for latching the beams to the fixed support to relieve tension from the cable when the boat is supported above the water line. 
     
     
         15 . The boat lift of  claim 1  further comprising a single power source for supplying power to all the lift mechanisms, the power source distributing power to the lift mechanisms to ensure that all the lift mechanisms move the same amount regardless of different loads on the different lift mechanism to maintain the boat level in the boat lift. 
     
     
         16 . The boat lift of  claim 1  in which at least one fixed supports is positioned on a walkway. 
     
     
         17 . The boat lift of  claim 1  in which at least one fixed supports is positioned on a post extending from under the water line. 
     
     
         18 . The boat lift of  claim 1  in which the cable is anchored to the fixed support by looping it through an opening, with a wedge positioned within the loop to maintain the cable in the fixed support. 
     
     
         19 . The boat lift of  claim 1  in which the beam includes at least one extension section that extends from a main beam section and in which a hydraulic cylinder is positioned at least partly within the extension section. 
     
     
         20 . The boat lift of  claim 1  in which the beam includes two extension sections and the lift mechanism includes two hydraulic cylinders, with a hydraulic cylinder positioned at least partly within each extension section. 
     
     
         21 . A lift system, comprising:
 a support beam for supporting a weight, the beam having an interior;   one or more cables;   a drive system for manipulating the one or more cables, wherein at least one component of the drive system is affixed within the interior of the beam, and a portion of the one or more cables affixed to the drive system such that such that operation of the drive system withdraws or extends the one or more cables into the interior of the beam.   
     
     
         22 . The lift system of  claim 21  in which the portion of the drive system affixed within the interior of the beam includes a hydraulic press having a movable piston, the one or more cables in contact with the piston. 
     
     
         23 . The lift system of  claim 21  in which the portion of the drive system affixed within the interior of the beam includes two or more spools, the one or more cables affixed to the two or more spools. 
     
     
         24 . The lift system of  claim 22  in which the two or more spools include intermating cogs, the cog of one spool in contact with the cog of the other spool, such that rotation of one spool causes equal but opposite rotation of the other spool. 
     
     
         25 . The lift system of  claim 23  having one cable, the cable having two opposite ends, each end affixed to a stationary object external to the interior of the beam, and wherein the portion of the cable affixed to the hydraulic press and movable piston is a center portion that encircles the hydraulic press and movable piston lengthwise, such that extension of the piston provides tension to the cable. 
     
     
         26 . A method for lifting a boat, comprising:
 providing at least one hollow beam;   providing a drive system having a plurality of components;   affixing at least one of the plurality of components within the hollow of the beam;   affixing at least one end of a cable to a stationary point external the hollow of the beam;   arranging one or more cables with the drive system, such that operation of the drive system causes the withdrawing or extending of the cables from within the hollow beam; and   operating the drive system.   
     
     
         27 . A lift system, comprising:
 a support member for supporting a weight;   one or more cables;   a drive system for manipulating the one or more cables, wherein at least one component of the drive system is affixed to the support member, and a portion of the one or more cables affixed to the drive system such that such that operation of the drive system withdraws or extends the one or more cables, causing the support member and the attached drive system to move in accordance to the withdrawing and the extending of the cables.   
     
     
         28 . The lift system of  claim 27 , wherein the drive system is mounted to a bottom side of the support member. 
     
     
         29 . The lift system of  claim 27 , wherein the support member includes a reinforcement member to reduce flexing of the support member caused by a weight supported by the support member. 
     
     
         30 . The lift system of  claim 27 , further comprising adjustable ends adjustably fastened to distal ends of the support member for adjusting the effective width of the support member. 
     
     
         31 . The lift system of  claim 27 , further comprising rollers at distal ends of the support members, the rollers having a grove to support the cable, such that friction is reduced as the cable is moved during operation of the drive system. 
     
     
         32 . The lift system of  claim 27 , wherein the drive system includes a hydraulic piston cylinder and piston. 
     
     
         33 . The lift system of  claim 27 , wherein the drive system includes one or more spools having cylindrical surfaces, the one or more cables attached to the bodies such that rotation of the spools causes the cables to wrap around the bodies. 
     
     
         34 . A cable fastening assembly comprising:
 a wedge having a groove along which a cable may align, the wedge having a tapered end and a wide end;   a mount having a slot for accepting the wedge and having means for attaching to a surface, wherein the slot is large enough to accept the tapered end of the wedge, but prevents the wide end of the wedge to be pulled fully through the slot, and wherein providing a cable through one end of the slot and along the groove of the wedge, and providing force to the cable to position the wedge in the slot causes the cable to bind.