Running water down.

[MoominPapa]

A couple of years ago, we were following a deep-draft boat up a lock flight. The boat was borrowed and the crew were not experienced, so I was assisting, at least partly to get them out of our way

 

The boat would not go over the bottom cill into a lock because the pound below was too low, so I opened the top paddles to let some water down. Whilst the water was flowing, the bottom gates were still open (the boat had retreated back into the pound.) It only occurred to me afterwards that this was possibly a dangerous thing to do: with water flowing through the lock, the bottom gates could have been caught by the flow and slammed closed, damaging the gates and anybody in the way of the balance beams.

 

So, is this a dangerous situation? Should I have closed the bottom gates and opened top and bottom paddles? This was a narrow canal, would the answer be different on a wide one?

 

What does the team think?

 

MP.

[RLWP]

A couple of years ago, we were following a deep-draft boat up a lock flight. The boat was borrowed and the crew were not experienced, so I was assisting, at least partly to get them out of our way

 

The boat would not go over the bottom cill into a lock because the pound below was too low, so I opened the top paddles to let some water down. Whilst the water was flowing, the bottom gates were still open (the boat had retreated back into the pound.) It only occurred to me afterwards that this was possibly a dangerous thing to do: with water flowing through the lock, the bottom gates could have been caught by the flow and slammed closed, damaging the gates and anybody in the way of the balance beams.

 

So, is this a dangerous situation? Should I have closed the bottom gates and opened top and bottom paddles? This was a narrow canal, would the answer be different on a wide one?

 

What does the team think?

 

MP.

 

I prefer to have the gates shut after we had one of the bottom gates slam on the Wolverhampton 21.

 

I have considered tying the bottom gate(s) open and just using the top paddles, but then it's only time after all. Gates shut and all paddles open works eventually.

 

Richard

[Hairy-Neil]

What does the team think?

 

MP.

 

 

There is that, but more likely is you will wash some underwater rubbish onto the cill and the gate will then not seal properly....

 

Is always safest to do it with gates closed, but paddles up.

[OptedOut]

We have in the past just left the boat part in the lock in gear with a top paddle open, the boat creeps in as the level rises.

Did it for about 15 minutes at Limehouse when the tide was coming in.

[WJM]

Unless you leave the bottom gates open and the ascending boat pressed up against the cill, how else will you know when you have let enough water through?

Edited December 18, 2008 by WJM

[alan_fincher]

BW staff will normally insist that if you are running water straight through a lock, to raise the level of the lower pound, that all gates are shut, so that water only passes through paddles.

 

If water is run down with the bottom gates open, there is some danger that muck will get washed down against inner end of the lower cill, such that the gates will then fail to seal properly.

 

However......

 

If it's a narrow lock, and you already have a boat part way in to it, it's very tempting just to wind a top paddle and open the throttle. Often the flush of water under the boat will get you in, without having to actually fill the depleted pound. The advantage of this, of course, is you have not drained a load of water from the higher pound, so there is much more chance you will be able to get into the next lock!

[Rick-n-Jo]

I had to refill a nearly empty pound on the Knowle flight a year or so ago. Having lifted a top paddle with the bottom gates open, I was surprised at just how fierce the flow through these big Grand Union locks is. By the time I noticed the gates begin to swing in the flow, it was of course far too late to wind the worm driven gear back down again. Those gates had picked up an impressive speed by the time they slammed.........

 

Won't be doing that again!

 

Rick

[MoominPapa]

Looks like the answer is "You got away with it this time, but don't do it again." Thanks Guys.

 

MP.

[WJM]

Of course, none of us ever use a small flush from the top paddle to close the bottom gates, do we?!

[alan_fincher]

Of course, none of us ever use a small flush from the top paddle to close the bottom gates, do we?!

I think many of us have experienced cases where it's necessary to "put a bit of paddle on" to hold one bottom gate shut against the wind, whilst we go round to close the other, (I have had such problems at Whilton, on the Regents, and on the Leicester, all within the last year).

 

But there's a world of difference between that, and having full top paddles open whilst the bottom gates get picked up and slammed closed by the full force unleashed. When it's as dramatic as that, you do risk doing serious structural damage, and, as someone implied, anybody unfortunate enough to be in the swept arc of the balance beams could be very severely injured, or even killed.

[WJM]

I had a group of gongoozlers observing me at the lock just beside the Islington tunnel. I explained to them that the lock was haunted by an invisible boatman who insisted on opening the bottom gate. I closed the top paddle that I had been using to make a small flush. Exactly on cue, the bottom gate swung open all by itself. How cool was that!

[Tim Lewis]

There is that, but more likely is you will wash some underwater rubbish onto the cill and the gate will then not seal properly....

 

Is always safest to do it with gates closed, but paddles up.

 

Fully agree with this.

 

Once this year I ran some water through a lock on the Stratford canal with the bottom gates open then had to spend half an hour trying to clear crap off the bottom cill so that we could shut the gates!

 

Tim

[DHutch]

Depends what your doing.

- If you refilling a short pound from a largish (or even simular sized one) then time doesnt really matter.

- However if you have a small pound, waters short, and the low pound is half a mile or so, bottom gates open gets you more flow, and means you can steam into the lock once afloat. Where you making use of the high flow rate and a time it takes to leval out to put a slope on the canal.

 

 

Daniel

[Keeping Up]

With a short pound you can sometimes flush yourself over the bottom cill by letting water down through the paddles and watching as the tidal wave rebounds from the top gates of the lock below. Just before it gets back to you, dropping the top paddles and giving a burst of throttle may get you in (but only if the gates are oprn of course)

[mykaskin]

If you want to get the quickest flow of water through a lock, then usually (though I guess it depends on paddle sizes), fix the top gate(s) open, and open the bottom paddles. It really gets a good flow running then! :-)

 

As already mentioned make sure the gates can't shut 'cause you get a really big and possibly dangerous bang. At least the top gates are usually a lot lighter than bottom gates, so would be easier for BW to fix! :-)

 

Cheers,

 

Mike

 

ps. This is only worth doing for serious bulk water movement - for just getting a boat in the lock I would use flushing (i.e. Lift the paddles, and motor against the flow).

[Jim]

I always leave the boat on the cill. The boat stops the gates from slamming shut when the paddles are raised and sometimes the extra water coming down the lock is enough in itself to lift her off. As has previously been said - in a short flight the action of letting a flash of water down and then waiting for it to come back from the lock below usually does the trick.

[DHutch]

If you want to get the quickest flow of water through a lock, then usually (though I guess it depends on paddle sizes), fix the top gate(s) open, and open the bottom paddles. It really gets a good flow running then! :-)

 

ps. This is only worth doing for serious bulk water movement

Yeah, as you say, for bulk water movement you will technicaly get more though the bottom gate paddles than a the top grounds. Unless you also have a decent gate paddle in the top gate. And the top gate is less likely to slam shut also.

However you are of cause usally trying to wash a boat into a lock from below. Or just fill a pound in which case i just open up at both ends with gates shut.

 

Daniel

[down the north]

re running water,

 

I've watched 'old time served' BW staff, ( where are they all now ) ? and the only way I'd run water is to fill the lock, leave top gate SHUT, both top paddles UP, then about 1 bottom paddle UP to keep the lock water level at least half full.

This stops the muck being dragged down the chamber and blocking the mitre arc described by the bottom gates.

 

Martin

[MK Mishra]

re running water,

 

I've watched 'old time served' BW staff, ( where are they all now ) ? and the only way I'd run water is to fill the lock, leave top gate SHUT, both top paddles UP, then about 1 bottom paddle UP to keep the lock water level at least half full.

This stops the muck being dragged down the chamber and blocking the mitre arc described by the bottom gates.

 

Martin

 

It is a idom. water is fall down everytime so we should down and think cool.

[Nickhlx]

It is a idom. water is fall down everytime so we should down and think cool.

 

 

errr - I don't understand what you said..

 

Nick

[ditchcrawler]

errr - I don't understand what you said..

 

Nick

glad I'm not the only one

[Smelly]

Makes sense (to me at least) to hold the top gate open and use the bottom paddles if you're struggling for level in the pound, that way you get the head of water to speed things along. Otherwise if you're stuck on the cill; or even as was once the case stuck widthways coming out of a lock on a rather hogged wooden hull, I'd go with what's already been said about flushing.

[ditchcrawler]

Makes sense (to me at least) to hold the top gate open and use the bottom paddles if you're struggling for level in the pound, that way you get the head of water to speed things along. Otherwise if you're stuck on the cill; or even as was once the case stuck widthways coming out of a lock on a rather hogged wooden hull, I'd go with what's already been said about flushing.

Its not the flushing, its Fall down water being cool that I didn't get

[magpie patrick]

I do wonder if MK Mishra has been trying the towpath mushrooms, as that certainly doesn't make sense!

 

However, back to the main point about running water thorugh a lock. From experience, close gates at both ends and then open the paddles at both ends. At Hatton, BW advise a third of a paddle (but they are big paddles) around the BCN, and on the Grand Union, I've opened the lot.

 

Surprisingly if you do this the lock typically holds between half and two thirds full

[Smelly]

Its not the flushing, its Fall down water being cool that I didn't get

 

Sorry I wasn't referring to the confusing post just expressing an opinion on the OP!