Boat lift

A boat lift, ship lift, or lift lock is a machine for transporting boats between water at two different elevations, and is an alternative to the canal lock and the canal inclined plane.
It may be either vertically moving, like the ship lifts in Germany, Belgium, the lift at "Les Fontinettes" in France or the Anderton boat lift in England, or rotational, like the Falkirk Wheel in Scotland.
History.
A precursor to the canal boat lift, able to move full-sized canal boats, was the tub boat lift used in mining, able to raise and lower the 2.5 ton tub boats then in use. An experimental system was in use on the Churprinz mining canal in Halsbrücke near Dresden. It lifted boats using a moveable hoist rather than caissons. The lift operated between 1789 and 1868, and for a period of time after its opening engineer James Green reporting that five had been built between 1796 and 1830. He credited the invention to Dr James Anderson of Edinburgh.
The idea of a boat lift for canals can be traced back to a design based on balanced water-filled caissons in Erasmus Darwin's Commonplace Book (page 58-59) dated 1777–1778
In 1796 an experimental balance lock was designed by James Fussell and constructed at Mells on the Dorset and Somerset Canal, though this project was never completed. A similar design was used for lifts on the tub boat section of the Grand Western Canal entered into operation in 1835 becoming the first non-experimental boat lifts in Britain and pre-dating the Anderton Boat Lift by 40 years.
In 1904 the Peterborough Lift Lock designed by Richard Birdsall Rogers opened in Canada. This high lift system is operated by gravity alone, with the upper bay of the two bay system loaded with an additional of water as to give it greater weight.
Before the construction of the Three Gorges Dam Ship Lift, the highest boat lift, with a height difference and European Class IV (1350 tonne) capacity, was the Strépy-Thieu boat lift in Belgium opened in 2002.
The ship lift at the Three Gorges Dam, completed in January 2016, is high and able to lift vessels of up to 3,000 tons displacement.
The boat lift at Longtan is reported to be even higher in total with a maximum vertical lift of in two stages when completed.