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Lock gate damage Worcester

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It has ‘bent’ in the direction one would push to open the gates.  Do they have any evidence to point to vandalism rather than a complete lack of inspection and replacement?  Whilst they may claim it is difficult to assess the depth of rot, BT & electric distribution companies seem to manage without their wood poles continually snapping and falling over.

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This was taken on 3rd March this year - no obvious maintenance problem. (Not the best of pix but the weather was not the best at the time)

Bilford Top.jpg

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This photo seems to show a lot of rot.

 

Could well be vandalism but its not like they took a chain saw to it.

 

 

245408667.jpg.gallery.jpg

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Could have been a group of people pushing on the beam against a head of water. But with that much rot it would have failed soon anyway.

Edited by David Mack

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1 hour ago, David Mack said:

Could have been a group of people pushing on the beam against a head of water. But with that much rot it would have failed soon anyway.

You mean like a couple of boaters trying to open the gate a little early??

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22 minutes ago, Chewbacka said:

You mean like a couple of boaters trying to open the gate a little early??

Or half a dozen board walkers seeing if they can open a gate without a windlass 

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3 hours ago, Chewbacka said:

It has ‘bent’ in the direction one would push to open the gates.  Do they have any evidence to point to vandalism rather than a complete lack of inspection and replacement?  Whilst they may claim it is difficult to assess the depth of rot, BT & electric distribution companies seem to manage without their wood poles continually snapping and falling over.

 

Used to be done by hitting the pole with a hammer and an experienced man listening to the sound.

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In good condition you could drive a tractor into a beam that size and it wouldn't snap. Looking at the pictures is would suggest there was only an inch or so on one side of decent wood, the rest being held by the paint.

 

But on the bright side for once it is not boaters to blame.

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15 minutes ago, Detling said:

 

 

But on the bright side for once it is not boaters to blame.

Do we know that

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1 hour ago, Chewbacka said:

You mean like a couple of boaters trying to open the gate a little early??

 

18 minutes ago, Detling said:

In good condition you could drive a tractor into a beam that size and it wouldn't snap. Looking at the pictures is would suggest there was only an inch or so on one side of decent wood, the rest being held by the paint.

 

But on the bright side for once it is not boaters to blame.

 

 

Met a bloke a few years ago using an acroprop to open lock 5 on the Rufford Branch.

"They've all been like this - lack of bloody maintenance." he said.

"I have just caught up with you and not needed one" I said.

Then I noticed he wasn't bothering to open the offside paddles.

"Oh," he said, "There's no need to cross over and do them - I have a prop!"

The balance beam was bending about a foot before the gates moved.  The level was 5" off at the time.

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12 hours ago, TheBiscuits said:

Met a bloke a few years ago using an acroprop to open lock 5 on the Rufford Branch.

 

"They've all been like this - lack of bloody maintenance." he said.

"I have just caught up with you and not needed one" I said.

Then I noticed he wasn't bothering to open the offside paddles.

"Oh," he said, "There's no need to cross over and do them - I have a prop!"

The balance beam was bending about a foot before the gates moved.  The level was 5" off at the time.

Sounds like much harder work that lifting a paddle.

 

My maths suggests that that the force on a (2.4m) gate due to a head of 0.15m  is only 220 newtons - or about 60 lb force. Seems low but if correct(!), bearing in mind you have a long lever in the balance beam, it isn't much at all.  Certainly one is frequently told that the gates are not ready to open, when they demonstrably are.  In fact, they are always ready to open if you can push hard enough.  

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13 hours ago, Detling said:

But on the bright side for once it is not boaters to blame.

How infuriating for CRT whose approach to maintenance nowadays is to wait for things to break from old age and then blame boaters.

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1 hour ago, Tacet said:

Sounds like much harder work that lifting a paddle.

 

My maths suggests that that the force on a (2.4m) gate due to a head of 0.15m  is only 220 newtons - or about 60 lb force. Seems low but if correct(!), bearing in mind you have a long lever in the balance beam, it isn't much at all.  Certainly one is frequently told that the gates are not ready to open, when they demonstrably are.  In fact, they are always ready to open if you can push hard enough.  

Pru on one of the boating programmes  said the gate is like a woman - it lets you know it is ready with a little sigh...

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1 hour ago, Tacet said:

Sounds like much harder work that lifting a paddle.

 

My maths suggests that that the force on a (2.4m) gate due to a head of 0.15m  is only 220 newtons - or about 60 lb force. Seems low but if correct(!), bearing in mind you have a long lever in the balance beam, it isn't much at all.  Certainly one is frequently told that the gates are not ready to open, when they demonstrably are.  In fact, they are always ready to open if you can push hard enough.  

 

Oh I agree, it's how I caught up with him despite all the locks being against me!

 

That 220N / 60 lb force does seem far too low to me, and I say that as a compulsive lock gate pusher, who opens gates before true equilibrium is reached.  I can't think of any lock where I could force a gate with a 6" difference, and I'm pretty sure I can apply a lot more force than that!

 

Could you show your workings please?  I'm wondering how you got that number.

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I agree, the figure of 60lb force sounds far too low for a 6" head of water. But I haven't done the maths myself either.

 

Once when we approached a lock we could see a group of teenagers waiting around it, and had been warned by another boater to expect trouble from them. As the lock filled, we chatted to them and my wife held a £5 note aloft and bet them that they couldn't open the gates before her. With each of them in turn trying to impress the others (and win the money) the gates of course wouldn't shift. When there was about 6" to go and nobody could shift it, my wife called off the bet and said she would show them how it was done. Deliberately taking her time, so that there was only about 1" of difference in the level, she casually pushed it open with just one hand. They looked at her in awe as if she was some kind of Superwoman!

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2 hours ago, TheBiscuits said:

 

Could you show your workings please?  I'm wondering how you got that number.

It does seem low to me too- but here goes:

 

According to this, https://www.instructables.com/id/Solving-for-the-Force-Exerted-on-a-Dam-by-Water/ the formula is: Force = density x g x h/2 x area

 

So taking a gate as having a width of, say, 2.4m with a difference of 0.15m

 

1000kg/m3 x 9.81m/s-2 x .015/2 x .15 x 2.4 = 220.75 Kgm/s2 or Newtons, if you prefer

 

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7 minutes ago, Tacet said:

It does seem low to me too- but here goes:

 

According to this, https://www.instructables.com/id/Solving-for-the-Force-Exerted-on-a-Dam-by-Water/ the formula is: Force = density x g x h/2 x area

 

So taking a gate as having a width of, say, 2.4m with a difference of 0.15m

 

1000kg/m3 x 9.81m/s-2 x .015/2 x .15 x 2.4 = 220.75 Kgm/s2 or Newtons, if you prefer

 

That is the force which applies to the top 0.15m of the gate which has water on one side but not on the other. But the pressure difference also applies to the whole of the gate which is below water both sides. And that is an order of magnitude higher.

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3 minutes ago, David Mack said:

That is the force which applies to the top 0.15m of the gate which has water on one side but not on the other. But the pressure difference also applies to the whole of the gate which is below water both sides. And that is an order of magnitude higher.

I think you're right.  I've worked it out again using 1.5m one side and .15m less the other and it comes out at 5kN - or c500kgf.  Which sounds much more plausible.  Say two or three fat blokes pushing hard with the mechanical advantage of the balance beam at maybe 3:1.

 

 

 

 

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2 minutes ago, Tacet said:

I think you're right.  I've worked it out again using 1.5m one side and .15m less the other and it comes out at 5kN - or c500kgf.  Which sounds much more plausible.  Say two or three fat blokes pushing hard with the mechanical advantage of the balance beam at maybe 3:1.

 

Which makes it even more impressive when a 4ft 80 year old woman does it on her own when her 6ft 20 stone husband is stood on the back of the boat shouting at her. :D

 

We did once use half a rugby team coming down the Rochdale 9 with a 4" overflow over the top gates.  That nicely fits with your multiple-fat-blokes-pushing units ...

 

I'd say that sounds close enough for what are are looking at, and half a tonne of force sounds likely when I have had to use a spanish windlass on the odd occasion.   Please note I'm not in Worcester though, so the lock in question wasn't me!

 

 

 

 

 

 

 

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8 hours ago, Keeping Up said:

I agree, the figure of 60lb force sounds far too low for a 6" head of water. But I haven't done the maths myself either.

 

Once when we approached a lock we could see a group of teenagers waiting around it, and had been warned by another boater to expect trouble from them. As the lock filled, we chatted to them and my wife held a £5 note aloft and bet them that they couldn't open the gates before her. With each of them in turn trying to impress the others (and win the money) the gates of course wouldn't shift. When there was about 6" to go and nobody could shift it, my wife called off the bet and said she would show them how it was done. Deliberately taking her time, so that there was only about 1" of difference in the level, she casually pushed it open with just one hand. They looked at her in awe as if she was some kind of Superwoman!

 

One of my party tricks when I was an eight stone teenager was to rip a telephone directory in half (when telephone directories were 2 or three  inches thick, not the thin pamphlets of today).

 

It always impressed the girls and drove the boys mad when they couldnt do it.

 

The trick was to break the spine and rip from spine to open pages. Most people try to rip from open pages towards the spine.

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6 hours ago, Tacet said:

I think you're right.  I've worked it out again using 1.5m one side and .15m less the other and it comes out at 5kN - or c500kgf.  Which sounds much more plausible.  Say two or three fat blokes pushing hard with the mechanical advantage of the balance beam at maybe 3:1.

 

And using your numbers, and a spreadsheet, this is how the force on the gate varies with level difference.

Graph.png.d4bbb324af69d665edcaee5bea1aa785.png

 

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On 31/03/2020 at 18:13, StephenA said:

This photo seems to show a lot of rot.

 

Could well be vandalism but its not like they took a chain saw to it.

 

 

245408667.jpg.gallery.jpg

Seems to be a very bad design to me. The steel plate and the bolts going through the wood is asking for trouble. 

 

Plus the external paint is not going to help. 

 

I'm sure in the old days these railings, if present, were spiked to the wood rather than bolted. 

 

And of course the hardware was replaced more often when the waterway was used as a commercial highway. 

 

 

To quote (or misquote but it gets the message across) Tony Dunkley "at least CRT admit to being vandals". 

 

Edited by magnetman

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