The Falkirk Wheel

March 11, 2008 at 9:13 am | Posted in technology | 8 Comments

Wow. This is some cool stuff. The Falkirk Wheel is a engineering feat in Scotland that essentially replaces locks to move large boats up and down in elevation while traveling rivers. Here’s a video.

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  1. Neat invention. The one big problem here is that the boats must be small enough to fit through the wheel’s hoops, and the wheel has the be able to carry the weight of the boat and water.

    You probably couldn’t make a Falkirk wheel big enough to move something very large (like a cruise ship or an aircraft carrier). So major canals (like the one in Panama) are still going to require locks.

  2. Part of the beauty of the wheel is that, if there are boats of roughly equal mass (or sets of boats with roughly equal total mass) going both ways, they can adjust how much water goes in each “tub” so the mass in both “tubs” are equal. In this case, rotating the wheel takes MUCH less energy.

    I don’t know how often this happens, but from the (admittedly limited) reading I’ve done it happens often enough that this is a major advantage of the design.

    • It’s even better than you think. There is NO adjustment needed. One “tub” can be filled with boats and the other have no boats at all and it remains perfectly counterbalanced. As Archimedes discovered millenia ago, something that floats in a liquid displaces exactly it’s own weight in liquid. So there is no adjustment necessary; move a boat into the caisson and it displaces its exact weight in water leaving the caisson with the same weight as before. In honor of this principle, one of the tour boats is named after Archimedes.
      Bob

      • So each tub is filled to capacity all the time, so when boat enters the tub there is no adjustment needed. Brilliant! Gotta love the scots.

      • Sure, if the boats can be kept floating while they’re in the tubs. That is going to seriously limit the size of the boats.

        Keep in mind that major canals can move ships with displacements on the order of tens of thousands of tons. It would be extremely difficult to make any kind of container that can lift this much weight, whether it is water or ship.

        This is one of those places where theory and practice are not going to arrive at the same conclusions.

  3. Dave, I don’t understand where your theory/practice comment is coming from. You seem to arguing against replacing all locks everywhere with Falkirk wheels when there has been no such suggestion (on this blog, at least).

    The website linked to above acknowledges that each tub carries 300 tons of water, so the weight of a ship would be limited to about 200 tons. http://www.falkirk-wheel.com/faq-s-on-the-falkirk-wheel/what-is-the-maximum-weight-and-length-of-boat-that-can-be-transported-by-the-wheel.html

  4. Sorry about that. There seemed to be a strong implication on “… and therefore locks are unnecessary and wasteful” in the comments.

  5. No prob. IIRC, the Falkirk wheel replaced 11 locks in that section of river, and that greatly reduces the time it would take for a boat to traverse that section of river. I’m not sure which uses more energy/water for its operation, and even if the FW is more efficient, I wonder how long it would take to save enough money/resources to offset the investment of building the wheel.

    When I go to Ireland and Scotland one of these years, I’d like to check it out as one of my “touristy” destinations.


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