A new solution to an old problem...

Here is the problem - you have a canal, and it either needs to change height (think long "sloping" canal), or intersect another canal system or river at another height (this would correspond to the "waterfall running into another river".

Well, there is a classic solution to this problem, one that has developed over the years into a fine art - the "Lock". If you never actually sat down to think how they work, it is fascinating in its simplicity. Here is a cool simulation that shows the basic idea.

Summary of cool points:

1. The lock can operate in both directions - boats can go up and down


2. It theoretically takes no energy to run the lock, if you don't count the change of height in the water. Put another way, no water is pumped, and there is only friction on the doors.


3. It is pretty fail safe. By angling the doors slightly toward the upstream end, it can be arranged that the pressure of the water against the doors forces them closed - only after the water level is equalized will it be possible to open them. Terrorist-proof!

This does not mean that locks are not without a few problems:

1. There is a practical maximum height to a lock. If the lock gets too high, those really tall doors have to be quite strong to hold back the water. Note that the door height it not the depth of the canal, but rather then drop required plus two times the canal depth. When there is a big drop, a sequence of locks must be used - in some cases upwards of a dozen. It takes a long time to traverse these, and people get bored.


2. You have to fill those big locks full of water each time, and the water height is again twice the canal depth PLUS the drop across the lock (this is true even with cascaded locks). And of course the volume is proportional to the length of the lock. All of this filling takes a lot of time, and it can actually take a lot of water. If the drop is high and the canal shallow, the canal gets to flow like a river, even if it is flat!

Well, there is another way, it has just been impractical until recently. Consider if you could take a strip of the canal, ship and all, lift it with a crane (think LARGE bathtub!), rotate the crane and place it alongside the (lower) canal. Then open the walls to the bathtub and off goes the ships.

Well, cool idea, but not practical. Consider:

1. One hell of a big and heavy bathtub! No crane is going to be able to life it.


2. It would take a lot of energy to move the bathtub uphill! Bundles of energy.


3. Big disaster in the making. Heck, we can't even build bridges without them falling down occasionally.

And that's how the world stayed - until 2002. But not so fast - it wouldn't be fun for me!

The first step is to take a lesson from a vernicular. There are the cable cars that ride up and down a mountain, usually in pairs. They take little energy, because the car going down helps to pull the car going up - if the passenger weights match exactly no energy is required.

How does this relate to our canal problem? Well, let's take the bathtub now, put it on wheels with a cable arrangement, and make a vericular. Now we have solved the energy problem, provided the cable does not break. And you get a bonus - it doesn't even matter how much the ships weight, because they displace exactly their weight in water (think about this some...).

Now we get to our modern solution. Since pictures are worth a thousand words, take a look at this link on the Falkirk Wheel.

Talk about cool things! If you want to see it in motion, click this link and select the "presentation video".
Now, a couple of things I find are really cool about this:

1. The two sides exactly counterbalance each other. They claim that to perform a rotation uses about as much energy as boiling 6 tea kettles of water!
2. It is pretty fail safe - no cables to break
3. It uses some really techie gear work to keep things from spilling. Interested? Read about it here.
4. Form followed function, but the form is really nice!
5. It uses very little water - only to the depth of the canal. And water is returned, in a way. Put another way, although some mixing occurs, the same water keeps going back and forth (except that "vacated" when the boats leave). So you could say that no net water is transferred between the canals (or two rivers). Compare that with the canal lock system (it is estimated that if the Falkirk wheel was built, the previous system in the same place took 11 locks).

Isn't technology wonderful?