Panama Canal

[Fredxx]

And a small sip in a big lock uses the same amount of water as a big ship.

[Rod Speed]

Nope, the small ship displaces less water and a lock that can take a big ship needs much more water to fill it.

[Reentrant]

Another counter-intuitive fact - the western-most end of the canal meets the Caribbean, and the eastern-most end meets the Pacific.

[The Natural Philosopher]

But only just... In reality its mostly north/south

[Fredxx]

Yes, it displaces the same volume of water before entering the lock, in the lock, and exiting the lock.

In the mean time a lock full of water would have been dumped from above the lock to below the lock.

If you feel that the water displaced by the boat has a different density, then I can see where you're going wrong.

[Fredxx]

I was wondering the same, as multiple side pounds per lock can drastically reduce water usage (to a ~single side pond if of equal size).

[Tim Streater]

About 25 miles, AFAICT from Giggle maps.

Yeah, around 50 miles.

[alan_m]

That's not necessarily how most of the locks work. They have side pools. When a boat is lowered the water can be pumped to a side pool rather being dumped to a lower lock. The water in the side pool can then be pumped back to raise a boat. Panama has sets of parallel locks. The water from a full lock can be pumped sideways to fill a empty lock and then pumped back again when the original lock needs refilling.

Some locks on British waterways also have similar water saving side pools but are not so efficient for saving water as they operate by gravity rather than being pumped.

[Fredxx]

I can only think of 3 locks in the UK with side pounds. However the water usage is still independent of size of boat/ship. But yes you are right about the use of side pound, something I forgot at the time of writing.

[Jeff Gaines]

The Caen Steps are a good example:

[Fredxx]

I was thinking of side ponds rather than pounds:

but I couldn't find a better aerial photo with a side pond next to a lock. An explanation here: "Locks 1,2 & 3 on the Droitwich Junction Canal have about a 15 foot deep drop. They have side ponds halfway down so that (if used) only a 7.5 ft height of water is passed down to the next lock. This supplies the the rest of the locks on the Junction canal the right amount of water for boats to pass; having themselves only 7.5 ft drops."

Though few know how to operate the various paddles despite instructions!!

[Tim Lamb]

I shower so it is a long time since I had any actual experience of your claim. But, surely the volume of water required to fill must vary with that displaced by the vessel?

>

[Fredxx]

Yer but:

x = weight of water in a full lock y = weight of water in an empty lock

I look at it this way. A 10 ton boat will displace 10 tons of water. So after entering a conventional lock from above there will be (x - 10) tons of water in the lock after the gates are closed.

When you lower the water level a convention lock, the lock will now contain (y - 10) tons of water.

Either way (x - y) = ((x - 10) - (y - 10)) The water emptied out of the lock is independent of the displacement of the boat.

It is logical, as the water you empty is area is always lock x reduction of height in lock. The only proviso is that boat is floating at all times.

[Rod Speed]

Fredxx [e-mail] wrote

Even sillier and more pig ignorant than you usually manage and that's saying something.

Never ever said anything even remotely like that.

[Rod Speed]

Don't need any of that crap.

Even you should be able to grasp that the amount of water needed in the lock is MUCH higher when the vessel is a small yatch and a f****ng great PANAMAX

[Fredxx]

Yes, I can grasp the issue is loss of water, not the actual water in the lock.

When you can do the same you can move forward.

[Rod Speed]

The water in the lock is what matters when discussing why the panama canal has a problem in a drought.

Something you can't manage due to the problem between your ears.

[Fredxx]

Is that an admission "Nope, the small ship displaces less water and a lock that can take a big ship needs much more water to fill it" was a load of BS?

At least I have some grey matter between my ears.

[Max Demian]

SEP (Someone Else's Problem).

[Rod Speed]

Nope, that is a fact that you are too stupid to understand.

When you have a massive great lock that can take a PANAMAX and its a much smaller vessel moving thru the canal, OF COURSE you lose a lot more water with the smaller vessel.

That is very far from clear.