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Closing Lock Gates


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41 minutes ago, MtB said:

 

 

Why do you need legislation to make you do something blindingly obviously sensible, and to your own and everyone else's benefit?

 

Because it's not immediately to your own benefit, it's much less effort leaving gates open and paddles up, especially when single-handing?

 

Which is essentially saying "I'm all right Jack", easier if somebody else does the hard work for you... 😞

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47 minutes ago, Loddon said:

If no-one shut gates then overall everyone would have to do less opening/closing gates. 😱

I think that was the conclusion when this was discussed previously. Basically the advantage of being able to go straight into a lock when it is in your favour outweighs the disadvantage of having to shut the gates and paddles at the far end when it is not, since you have to be off the boat to work the lock anyway. 

But that is only the case if everybody does it. If some do and some don't then feelings of unfairness come to the fore. And the water saving arguments favour shutting all gates and paddles.

But what does surprise me is that for a practice which is now more or less universal on CRT waters, there seems to be remarkably little mention of it on the CRT website. So how is this concept disseminated?

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As was said in BW days if the locks were maintained properly then we wouldn't have to shut the gates.

 

Why is there no flying pig emoji? I suspect it's hiding along with the tongue in cheek one

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1 hour ago, Loddon said:

If no-one shut gates then overall everyone would have to do less opening/closing gates. 😱

As a confirmed singlehander (just noticed that's a euphemism, but never mind, the mods will never spot it), I've never been convinced of that.

I suspect it would only be true on a very busy stretch with people going both ways. I've noticed that on the unbalanced gates that swing open, they're always at the wrong end of the lock for the way I'm going...

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18 hours ago, Martin Nicholas said:

There's no mention of this in the "GENERAL CANAL BYE-LAWS: Operation of Locks", so it's not the law.

 

Closing the bottom gates on an empty lock saves no water. For maximum leakage be sure to lave a lock full with the top gate(s) floating.

 

The recommendation is "after use", not "after each use" or "after every use", so not needeed on a busy lock is in constant use throughout the day.

It does if the top gates leak but the bottom gates don't.  The lock will gradually fill and the bottom gates will hold it.  If the bottom gates are left open, the pound above will gradually drain.

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27 minutes ago, Loddon said:

As was said in BW days if the locks were maintained properly then we wouldn't have to shut the gates.

 

Why is there no flying pig emoji? I suspect it's hiding along with the tongue in cheek one

Though even if the locks were maintained to perfection reeds rubbish even tyres and stuff can get caught in the gates or gate paddles/ sluices causing leakage. 

 

Ive always understood that closing even bottom gates can save water, as a leaking top gate will get so full then stop leaking. If top and bottom gates leak its not ideal, though both usually leak at different speeds. 

Edited by Stroudwater1
Edited, Dpra beat me to it
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39 minutes ago, Stroudwater1 said:

Though even if the locks were maintained to perfection reeds rubbish even tyres and stuff can get caught in the gates or gate paddles/ sluices causing leakage. 

 

Ive always understood that closing even bottom gates can save water, as a leaking top gate will get so full then stop leaking. If top and bottom gates leak its not ideal, though both usually leak at different speeds. 

If both gates are closed then with leaky gates/paddles the water level in the lock drops until the same amount leaks in and out. If only one set is closed then this one sees the full head of water.

 

Since leakage goes up with water level difference, if both sets of gates are equally leaky (unlikely) closing both sets halves the leakage since the lock settles at half-full.

 

If one set is much leakier (more likely) than the least leaky one wins and restricts the flow through the leaky one, and the reduction in leakage is bigger than this, maybe 4x or 5x.

 

So a reasonable guess would be that closing both sets of gates typically reduces leakage by at least 3x -- which is why CART request it, given how many badly maintained leaky gates and paddles there are... 😞

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6 minutes ago, Loddon said:

Let's close gates in order to cover up Carts shoddy maintenance.

Why?

It's not done on other navigations why should it be done on canals.

You are being conned🤭

 

 

Absolutely. Let's all stick a finger up to CART by sitting on the bottom of empty pounds, that'll teach them... 😉

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Gates that are merely closed are not sealed. There are gaps between: the heel post and the quoin, the bottom of the gates and the cill and there is often a gap between the mitres. This is true even for brand new gates. They have to be this way so they can be opened and closed by a human. Once the gates have a head of water behind them they will settle into the cill and quoins, forming an effective seal.

 

This way you can get away with stone quoins and wooden heel posts. If there was a tight seal between the two, the gates would be too stiff to operate and the heel post would be worn out (and leak) in a week or so due to abrasion.

 

If a gate is unsealed (open) the only points of contact are the pin at the bottom of the gate and the collar at the top. This is why a gate can fall into the lock if the collar fails.

 

Look down at the bottom gates from a tail-bridge as the top paddels are lifted. Narrow, mitred locks, Fradley for example, are best. The gates lean backwards into their sealed position, hopefully snuggling into the quoins, pushing onto the cill and firmly closing the mitre. This phenomenon becomes more obvious as the gates wear.

 

Gates are designed to be completely unsealed with no head of water against them, for ease of use and to minimise wear. Once there is sufficient head of water then all the joints: the cill, the quoins and the mitre should be fully sealed by dint of the pressure.

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38 minutes ago, Loddon said:

Let's close gates in order to cover up Carts shoddy maintenance.

Why?

It's not done on other navigations why should it be done on canals.

You are being conned🤭

 

 

You have to conn boats, or they go all over the place.

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37 minutes ago, Loddon said:

Let's close gates in order to cover up Carts shoddy maintenance.

Why?

It's not done on other navigations why should it be done on canals.

You are being conned🤭

 

 

Because the other navigations where gates are left open are rivers, and so conservation of water is not an issue (except during periods of drought).

5 minutes ago, Martin Nicholas said:

Gates are designed to be completely unsealed with no head of water against them, for ease of use and to minimise wear. Once there is sufficient head of water then all the joints: the cill, the quoins and the mitre should be fully sealed by dint of the pressure.

Indeed. But if there is significant leakage at the other end of the lock a level difference will build up which will eventually force the gates to a full seal, and hence reduce the overall loss of water. If the gates at the other end are completely tight, then this doesn't happen, but then it doesn't matter.

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25 minutes ago, David Mack said:

Because the other navigations where gates are left open are rivers, and so conservation of water is not an issue (except during periods of drought).

They  mostly  have gates and paddles that don't leak, also the navigation authority are on top of maintenance to keep it that way.

Let's face it cart are crap at maintenance and making navigation simple and easy.

Edited by Loddon
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1 hour ago, Loddon said:

They  mostly  have gates and paddles that don't leak, also the navigation authority are on top of maintenance to keep it that way.

Let's face it cart are crap at maintenance and making navigation simple and easy.

 

I agree the maintenance isnt great but as Martin Nicholas describes above that isnt often the issue. Its worth adding Its often boaters to blame by not fully lowering the paddles- thats is often more of a problem IMHO these days.

 

Last year one pound on Marple when the flight was locked top and bottom by CRT had one top gate ground  paddle left up. The lower gate was leaking badly and almost the whole pound above  was empty. If the paddle had been proerly lowered then its likely the lock would have drained down to the leak, stopped and the pound above would be full still. I imagine CRT ought to have noticed but it was a boater that that had left the paddle up we were told by another boater. 

 

 

 

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9 hours ago, MtB said:

 

 

Why do you need legislation to make you do something blindingly obviously sensible, and to your own and everyone else's benefit?

 

 

I always close lock gates as I said earlier.

I did not say there should be legislation but it was implied there were rules or regulations or C&RT instruction  and it appears not to be so.

 

But reading what other people have to say it seems closing  gates  appears not to be so blindingly obviously the right thing to do  as you think it is. 

 

 

 

 

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12 minutes ago, MartynG said:

 

I always close lock gates as I said earlier.

I did not say there should be legislation but it was implied there were rules or regulations or C&RT instruction  and it appears not to be so.

 

But reading what other people have to say it seems closing  gates  appears not to be so blindingly obviously the right thing to do  as you think it is. 

There are certainly CRT instructions that all gates should be left closed unless otherwise advised. Not every action we take has to be covered by legislation, thank god.

There are all sorts of opinions about boat etiquette, which is why this is a forum for discussion, but CRT's position on this is quite clear.  It does mean that first time hirers and the inexperienced may make the odd mistake, but the consequences shouldn't lead to empty pounds too often. It's a commonsense solution, deliberately ignored by a few selfish people  as most commonsense things are.

 

 

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7 hours ago, IanD said:

 

 

Since leakage goes up with water level difference, if both sets of gates are equally leaky (unlikely) closing both sets halves the leakage since the lock settles at half-full.

 

If one set is much leakier (more likely) than the least leaky one wins and restricts the flow through the leaky one, and the reduction in leakage is bigger than this, maybe 4x or 5x.

 

So a reasonable guess would be that closing both sets of gates typically reduces leakage by at least 3x -- which is why CART request it, given how many badly maintained leaky gates and paddles there are... 😞

This depends on whether the gates are equally leaky throughout their entire height.   And if they are, then half height with half the pressure is probably around a quarter of the loss.

 

A very valid argument used to be that leaving the gates open gives someone who falls in the lock a better chance of survival.  A little less valid now that most locks have ladders

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On 16/05/2022 at 09:28, David Mack said:

I think that was the conclusion when this was discussed previously. Basically the advantage of being able to go straight into a lock when it is in your favour outweighs the disadvantage of having to shut the gates and paddles at the far end when it is not, since you have to be off the boat to work the lock anyway. 

But that is only the case if everybody does it. If some do and some don't then feelings of unfairness come to the fore. And the water saving arguments favour shutting all gates and paddles.

But what does surprise me is that for a practice which is now more or less universal on CRT waters, there seems to be remarkably little mention of it on the CRT website. So how is this concept disseminated?

 

Just did Tardebigge, which disseminates the concept with signs on gates telling you to shut them :D

 

Since they were in my favour, it would have been enormously faster and easier if I went straight in and out of locks, without any walking ahead to open the next gates whilst filling the lock, or any shutting gates after leaving locks. At least until I reached an empty pound.

 

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7 hours ago, enigmatic said:

 

Just did Tardebigge, which disseminates the concept with signs on gates telling you to shut them :D

 

Since they were in my favour, it would have been enormously faster and easier if I went straight in and out of locks, without any walking ahead to open the next gates whilst filling the lock, or any shutting gates after leaving locks. At least until I reached an empty pound.

 


The top gates on Tardebigge flight have a tendency to float open. It’s one reason that it routinely suffers from empty pounds.

 

If all the boaters that used the flight before you had left gates open you may have found your passage wasn’t as easy as you might think it would have been.

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I did say easy until I reached an empty pound! Some of the pounds looked a tad low already considering the rain

 

Actually seemed surprisingly non leaky especially considering some of the gates really are ancient, with only one or two of the locks being part filled. Although some of that may have been bottom gates floating open.

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I always shut gates, however I can't help feeling a bit frustrated when after leaving a lock, stopping the boat, tying up, walking back to the lock, walking around the lock to close the offside gate first (widebeam), walking back to the towpath side to close the other gate, walking back to the boat, untying and setting off.... to then look back and see that one or both gates have just swung open on their own. It usually happens when going uphill but what are you supposed to do? If you crack open a downhill gate paddle to put some pressure on the uphill gates to keep them closed you're going to leave the lock empty which defeats the object. If the uphill gates swing open on their own I just leave them.

Edited by blackrose
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3 hours ago, blackrose said:

I always shut gates, however I can't help feeling a bit frustrated when after leaving a lock, stopping the boat, tying up, walking back to the lock, walking around the lock to close the offside gate first (widebeam), walking back to the towpath side to close the other gate, walking back to the boat, untying and setting off.... to then look back and see that one or both gates have just swung open on their own. It usually happens when going uphill but what are you supposed to do? If you crack open a downhill gate paddle to put some pressure on the uphill gates to keep them closed you're going to leave the lock empty which defeats the object. If the uphill gates swing open on their own I just leave them.

If head gates are both closed for a while, it suggests to me that the tail gates are maintaining a good seal......

 

If you want to be super-perfect, you could draw a little off the lock which will keep the head gates closed.  

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