In some ways, building an elevator for ships is easier than building one for people or stuff; thanks to Archimedes Principle, it always weighs the same whether there is a boat in it or not, since the weight of the water displaced equals the weight of the boat.
So when they built this giant elevator at the Three Gorges Dam in China, they knew exactly how big to make the counterweights. It carries 6.7 million pounds of water and/or boat.According to Sploid, it used to take three hours to go through a series of five locks to get from the bottom to the top the dam. That’s hard on the tourist trade, so they installed the elevator that can do the trip in forty minutes to climb the 370 feet and is probably a pretty interesting ride all on its own.
The caisson (or chamber) is about 390’ by 60’ wide by 12’ deep, so bigger freighters are going to have to still take the locks. It has been a long time coming; it was first proposed 24 years ago, but according to the World Economic Forum,
According to Lu Youmei, former general manager of China Three Gorges Corporation, the original plan was to suspend the lifting chamber on steel cables. This plan was abandoned because of fears that the elevator could become unstable while lifting ships. In 2003, , the German company involved in the design, Krebs and Kiefer, introduced gear mechanisms instead of cables. This new design reassured the authorities that the system would be safe and work resumed on the elevator in 2008.
Like all counterbalanced elevators, it probably doesn’t take a lot of energy to run and it is, after all, part of the world’s largest hydro-electric dam. But it is a missed opportunity. In Peterborough, Ontario on the Trent Canal, they built a lift lock that uses no power at all- in 1904. There are two caissons instead of one, so that it can carry boats in both directions at the same time.
Since the chambers will weigh the same whether there is a boat in it or not, they just add a little water to the upper chamber and it will start sinking, pushing on a piston which will push water into the cylinder under the lower chamber and push it up. Why use electricity when Archimedes can do the work? And you get two elevators, probably for the price of one. Victorian engineering for the win.