High speed hydraulic watercraft lift

Abstract

A high-speed watercraft lift for raising and lowering a watercraft relative to a body of water, the lift comprising a cradle configured to support the watercraft, a cable suspending the cradle, a rotatable spindle configured take up the cable, and a submergible rotary motor. The cradle comprises a number of interconnected beams and a number of bunks connected to at least some of the interconnected beams. The cable is liftably linked to at least one of the interconnected beams. The rotatable spindle is configured to coil portions of the cable to raise the cradle and uncoil the portions of the cable to lower the cradle. The submergible rotary motor is configured to rotate the spindle.

Having thus described various embodiments of the invention, what is claimed as new and desired to be protected by Letters Patent includes the following: 
     
         1 . A lift for raising and lowering a watercraft relative to a body of water, the lift comprising:
 a cradle comprising:
 a plurality of interconnected beams; and 
 a plurality of bunks connected to at least some of the plurality of interconnected beams, the plurality of bunks being configured to support the watercraft; 
   a cable liftably linked to at least one of the plurality of interconnected beams;   a rotatable spindle configured to coil portions of the cable to raise the cradle and hence the watercraft and uncoil the portions of the cable to lower the cradle and hence the watercraft; and   a submergible rotary motor configured to rotate the spindle.   
     
     
         2 . The lift of  claim 1 , wherein the cable is connected to the at least one of the plurality of interconnected beams so that the submergible rotary motor evenly lifts the cradle. 
     
     
         3 . The lift of  claim 1 , wherein the lift is configured to be supported by pilings connected by piling members, and wherein the cradle is configured to be corralled by the lift structure when the cradle is in a stowed position to prevent swaying of the cradle. 
     
     
         4 . The lift of  claim 1 , further comprising a programmable logic controller (PLC) configured to control the submergible rotary motor. 
     
     
         5 . The lift of  claim 4 , further comprising an encoder communicatively connected to the PLC, wherein the PLC is configured to control the submergible rotary motor based on a position of the cradle determined via the encoder. 
     
     
         6 . The lift of  claim 5 , wherein the PLC is further configured to control the submergible rotary motor based on predetermined stop positions provided via user input. 
     
     
         7 . The lift of  claim 4 , wherein the PLC is further configured to decrease a speed of the submergible rotary motor when the cradle is near a stowed position. 
     
     
         8 . The lift of  claim 1 , wherein the submergible rotary motor is a hydraulic rotary motor. 
     
     
         9 . The lift of  claim 8 , wherein the lift is configured to be supported by pilings connected by piling members, and wherein the cradle is configured to be corralled by the piling members when the cradle is in a stowed position to prevent swaying of the cradle. 
     
     
         10 . The lift of  claim 8 , further comprising a brake configured to selectively prevent the cradle from being lowered. 
     
     
         11 . The lift of  claim 10 , further comprising a pressure compensating valve fluidly connected to the hydraulic rotary motor and configured to prevent the cradle from being lowered as the brake is being engaged and disengaged. 
     
     
         12 . The lift of  claim 8 , further comprising a programmable logic controller (PLC) configured to control the hydraulic rotary motor according to hydraulic pressure measured and monitored via the PLC. 
     
     
         13 . The lift of  claim 12 , wherein the PLC is configured to stop the hydraulic rotary motor if the hydraulic pressure is above a predetermined threshold. 
     
     
         14 . The lift of  claim 1 , further comprising a cable adjuster configured to engage the cable for adjusting a position of the cradle in a top position. 
     
     
         15 . A lift for raising and lowering a watercraft relative to a body of water, the lift comprising:
 a cradle comprising:
 a plurality of interconnected beams; and 
 a plurality of bunks connected to at least some of the plurality of interconnected beams, the plurality of bunks being configured to support the watercraft; 
   a plurality of cables liftably linked to at least one of the plurality of interconnected beams;   a plurality of rotatable spindles configured to coil portions of the plurality of cables to raise the cradle and hence the watercraft and uncoil the portions of the plurality of cables to lower the cradle and hence the watercraft; and   a submergible motor configured to rotate the plurality of spindles so that the motor evenly lifts the cradle,   wherein at least one of the plurality of cables is liftably linked to at least one of the plurality of interconnected beams at a lift ratio of 1:2 and at least one of the plurality of cables is liftably linked to at least one of the plurality of interconnected beams at a lift ratio of 1:3.   
     
     
         16 . A lift for raising and lowering a watercraft relative to a body of water, the lift comprising:
 a cradle comprising:
 a plurality of interconnected beams; and 
 a plurality of bunks connected to at least some of the plurality of interconnected beams, the plurality of bunks being configured to support the watercraft; 
   a plurality of cables liftably linked to at least one of the plurality of interconnected beams;   a plurality of rotatable spindles configured to coil portions of the plurality of cables to raise the cradle and hence the watercraft and uncoil the portions of the plurality of cables to lower the cradle and hence the watercraft; and   a motor configured to rotate the plurality of spindles so that the motor evenly lifts the cradle,   wherein at least one of the plurality of cables is liftably linked to at least one of the plurality of interconnected beams at a lift ratio of 1:2 and at least one of the plurality of cables is liftably linked to at least one of the plurality of interconnected beams at a lift ratio of 1:3,   wherein at least two of the plurality of rotatable spindles coil in opposite directions.   
     
     
         17 . A lift for raising and lowering a watercraft relative to a body of water, the lift comprising:
 a cradle comprising:
 a plurality of interconnected beams; and 
 a plurality of bunks connected to at least some of the plurality of interconnected beams, the plurality of bunks being configured to support the watercraft; 
   a plurality of cables liftably linked to at least one of the plurality of interconnected beams;   a plurality of rotatable spindles configured to coil portions of the plurality of cables to raise the cradle and hence the watercraft and uncoil the portions of the plurality of cables to lower the cradle and hence the watercraft; and   a motor configured to rotate the plurality of spindles so that the motor evenly lifts the cradle,   wherein the motor and at least two of the plurality of rotatable spindles are coaxial relative to each other.   
     
     
         18 . The lift of  claim 17 , further comprising a track, the cradle including a carriage configured to engage the track as the cradle is lifted. 
     
     
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         33 . A lift for raising and lowering a watercraft relative to a body of water, the lift comprising:
 a cradle comprising:
 a plurality of interconnected beams; and 
 a plurality of bunks connected to at least some of the plurality of interconnected beams, the plurality of bunks being configured to support the watercraft; 
   a cable liftably linked to at least one of the plurality of interconnected beams; and   at least two hydraulic rotary motors, one of the at least two hydraulic rotary motors positioned on a port side of the lift and one of the at least two hydraulic rotary motors positioned on a starboard side of the lift.