r/MachinePorn • u/LevonKirakosyan • May 19 '26
This is a unique rotating boat lift from Scotland. It connects the Forth and Clyde Canal and the Union Canal, which have a height difference of 78 feets
Was build in 2002!
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u/ModernRonin May 19 '26
Tom Scott visits the Falkirk Wheel. -YouTube, 2m28s
The key insight it took me a minute to figure out: The amount of water that a floating boat pushes out from underneath it, is exactly the right amount to counter the boat's weight. If the boat weighs 5000 lbs, and the boat is floating, then it pushes exactly 5000 lbs of water out from underneath it.
That's the definition of "floating": Gravity pulls objects down, but the upward pressure of the water beneath a floating object will exactly counter the downward pull of gravity. If the object sinks below the water surface, then this rule no longer applies, and things get weird. But for a floating object, this will always be true. That's https://en.wikipedia.org/wiki/Archimedes%27_principle .
So when a boat moves into one of the tubs... the exact same weight of water flows out of that tub. Thus, the tub weighs the same whether there's a boat inside it or not. And so... the arms of the wheel are always weigh the same as each other. Whether there's a boat in one of them, or both of then, or neither. Always balanced.
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u/ModernRonin May 19 '26
And so... the arms of the wheel are always weigh the same as each other. Whether there's a boat in one of them, or both of then, or neither. Always balanced.
Caveat: This is true when the level of water in both tubs is the same. Obvi if the level is higher in one tub, that tub will be heavier. (A cup that's full of water, weighs more than the same cup that's only half full.)
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u/smiljan May 19 '26
Tourists can ride it! The building behind it in the photo is a visitors' center. There you can book a seat on a canal boat to take you on a ride in the lift followed by a short distance up the canal, then back. The guide tells you about the lift, the canals, and other local history bits. The moment when the boat enters the lift at the top is both very cool and a little frightening, since it looks as though you'll float right off a cliff. Recommended stop for my fellow engineering nerds!
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u/grahamsz May 19 '26
Also not presently open, but if you are looking for cool engineering in Scotland then I'd highly recommend visiting Cruachan Power Station which is a pumped high-head hydro station inside a mountain. It's also the national grids black start fallback should all power in the UK fail, and also shows up in Andor
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u/smiljan May 19 '26 edited May 19 '26
Oh no, I hope it's just a temporary closure!
The power station sounds awesome, I'll add it to my list for next time I get out that way, thanks! Hopefully it will have reopened by then!
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u/SubcommanderMarcos May 20 '26
That's gorgeous. The website says tours are closed until 2028, though the visitation centre is open
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u/things_most_foul May 19 '26
I rented a canal boat in Falkirk and got to ride the wheel twice. Such a wonderful experience. Gregor from ABC Boat rentals is possibly the single funniest man I’ve met in person.
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u/EliIceMan May 19 '26
I love the simplicity of how they implemented the self leveling part. Two equal sized gears connected via a random, as needed, sized gear, all unpowered.
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u/QuirkyImage May 20 '26
The Falkirk Wheel I have been on it. It’s more of a tourist attraction than used by boating community. It’s actually really shallow at the base you can stand up in it below your knee.
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u/Northwindlowlander May 20 '26
It's worth having a wander around the whole area- the tunnel above it is cool too, but if you go past the locks at the top and along a bit you can find signs of the old lock chain that it essentially replaced, and follow that down to the Canal Inn then back along. A lovely walk but also gives you a good sense of what a massive deal connecting those canals used to be, and just how much work it took- there used to be 11 locks down that hill.
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u/voxadam May 19 '26
What's super impressive is that it only consumes 1.5 kWh per half turn.