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Who knows

It depends on where the water displaced by the barge goes.

If you put a bucket of water half full on some scales, then added a model boat weighing 1kg the scales would go up by that amount.

If the bucket was totally full of water and when you put the boat in the displaced water went over the top of the bucket, then the scales wouldn’t change.
Stick to dress making
 
It depends on where the water displaced by the barge goes.

It is spread throughout the canal system. Because the aqueduct is open at both ends. The water level in the aqueduct doesn't rise when a barge enters it.
 
I would say the answer is no.

The reason is because this:

If you imagine the canal is 10 miles long and closed at each end, the total weight bearing down on the bottom of the canal is the weight of the water plus all the barges floating on the water (because the barges cause an increase in the water depth in the canal)

water finds its own level so the water displaced by a barge is spread over the whole 10 miles of the canal.

The weight of the barge in question adds to the overall weight in the canal, so the aqueduct does experience an increase in weight as a result of the barge in the canal (as water displaced increases water level) but it makes no difference where the barge is in relation to the aqueduct. Weight doesn’t increase when the barge passes over the aqueduct.
 
It is spread throughout the canal system. Because the aqueduct is open at both ends. The water level in the aqueduct doesn't rise when a barge enters it.
Explained in my full answer above
 
I would say the answer is no.

The reason is because this:

If you imagine the canal is 10 miles long and a closed each end, , the total weight bearing down on the bottom of the canal is the weight of the water plus all the barges floating on the water (because the barges cause an increase in the water depth in the canal)

water finds its own level so the water displaced by a barge is spread over the whole 10 miles of the canal.

The weight of the barge in question adds to the overall weight in the canal, so the aqueduct does experience an increase in weight as a result of the barge in the canal, but it makes no difference where the barge is in relation to the aqueduct. Weight doesn’t increase when the barge passes over the aqueduct.

OMG! That's what I said! Hopefully we are right!
 
The Falkirk wheel shows up the problem.

If the Falkirk wheel has a boat in it, floating on the water does the wheel weight more than if there was no boat in it.
 
The mass of the boat displaces the water, depending how the displaced water reacts depends on where the load goes.

The amount the local aqueduct supports "feel" the additional mass is dependant on the wave/displacement caused.

Ultimately the weight will distribute over the whole water system, when it settles but in the short term depending on the speed of the vessel and therefore the wave height caused by the movement and displacement of the weight of the additional volume will bare on the supports.
 
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But is there ANY increase in pressure on the supports, as the boat passes over?
Yes temporarily due to the wave caused
No. Because nothing changes when the boat passes over. The aqueduct is open at both ends and is part of a much larger body of water i.e the canal system. If the boat wasn't situated above a particular support, then a weight of water exactly equal to the boats weight would be there instead. When the barge was first dropped into the canal system, maybe many years ago, there would have been an increase in weight spread across the whole canal system. But presumably the same weight of water would have drained out of the canal system somewhere to stop the water level from rising.
other than the wave caused by the boat displacing the water.

Once the boat stops and the water settles, you would be correct.

A bit of fun brain teaser.

I've asked it before on here but I don't think I got a definitive answer. The same question was put to my customers (both educated) and even those could not agree. They both argued about water displacement and physics.

Canal - aqueduct - barge passes over the aqueduct. Do the aqueduct supports feel the weight of the barge? I'm in the yes they do, camp.
Given the Barge is moving and therefore displacing water locally which has not settled across the whole system - the answer is yes.
 
Yes temporarily due to the wave caused

other than the wave caused by the boat displacing the water.

Once the boat stops and the water settles, you would be correct.


Given the Barge is moving and therefore displacing water locally which has not settled across the whole system - the answer is yes.
Except, of course, that the displacement of the barge moves away an equal weight of water, so the answer is no.

"Displacing water locally" raises the water level by a tiny amount over the entire canal. It might be enough to discern by precision measurement close to the vessel, but the boat does not have a footprint of increased pressure under it. Divers are not crushed every time a ship passes above.
 
Yes, the aqueduct supports do feel the weight of the barge.





Here’s why:





An aqueduct that carries a canal is essentially a bridge filled with water, and when a barge (or any boat) floats in that canal, it displaces water according to its weight (per Archimedes’ principle). The total load on the aqueduct structure remains the same whether it’s just water or water plus a floating barge—because the barge displaces its own weight in water.



Breaking it down:








  • The barge floats because it displaces a volume of water equal to its weight.
  • That displaced water pushes against the aqueduct structure just as the barge’s weight would.
  • So, the total downward force on the aqueduct supports remains unchanged: the weight of the water originally present is now distributed between water and barge, but the total is the same.


Conclusion:



✅ Yes, the supports feel the weight of the barge, but not more than the weight of the water it displaces—they effectively support whatever weight is sitting in the canal, barge or not.
 
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