Reasons For not Closing Lock Gates On The Southern GU

[Muddy Ditch Rich]

8 minutes ago, NB Lola said:

Then, in your eyes I stand guilty as charged.  I respect the guidance and the water conservation argument CRT will no doubt put.  However, in the interests of balance, I will ask CRT for the reason behind that guidance and publish here, if I get a response that is.  If the logic behind closing gates is floored then I would expect that this will open the floodgates of our respected conglomeration.  As single voices we both have our position and should maintain respectfulness, well, I will.

We already know what the Trust will say, they will just parrot " to conserve water". It is futile to ask them anything about boating or working locks, anyone who knew anything about such things left long ago when BW made their jobs impossible by their overbearing management.

 

[Theo]

Perhaps what I am going to say might be obvious but I will say it anyway.

1.  With leak free locks it is immaterial from a water conservation point of view whether gates are left open or shut.

2.  Leaving exit gates open will on average make locking more efficient because the lock will remain completely full or completely empty and there is the chance that the next boater will be able to go straight in.

3. With equal leakage at both ends closing up completely will reduce water loss by half.  This assumes that the rate of flow through the leaks is proportional to the water height difference.  After closing up the steady state will be  a half full lock which means that water will leak into the chanber at half the rate and out of it ditto.

Conclusion: Since CRT believe that the majority of boaters are enjoying the slow pace of canal boatiing rather than rushing to "get ahead" to catch the next cargo they are probably reasonable in asking us to close up at both ends.

Nick

 

[Mike Todd]

18 minutes ago, Theo said:

Perhaps what I am going to say might be obvious but I will say it anyway.

1.  With leak free locks it is immaterial from a water conservation point of view whether gates are left open or shut.

2.  Leaving exit gates open will on average make locking more efficient because the lock will remain completely full or completely empty and there is the chance that the next boater will be able to go straight in.

3. With equal leakage at both ends closing up completely will reduce water loss by half.  This assumes that the rate of flow through the leaks is proportional to the water height difference.  After closing up the steady state will be  a half full lock which means that water will leak into the chanber at half the rate and out of it ditto.

Conclusion: Since CRT believe that the majority of boaters are enjoying the slow pace of canal boatiing rather than rushing to "get ahead" to catch the next cargo they are probably reasonable in asking us to close up at both ends.

Nick

 

It is rare that leakage at both ends is the same. Hence it will rarely balance at half full. Unless one knows the lock well (every day as it can change quickly) there is limited chance that a boater will close the one that leaks less. Closing both doubles the chance that water loss will be reduced.

As a slight diversion, we came down the Leicester section a couple of weeks ago from Foxton and at the top locks (we moored just one down overnight) we were asked to delay setting off the next morning as the lockies (at least 2 if not 3) were running water down as the Shires lot needed more water to fill some very low pounds (some were still not over full when we reached them. The explanation was that the upper flight had been worked on over the winter and now leaked very little unlike those below Kilby. As a result, not enough water was getting down the flight - as had been happening hitherto. Amusingly, that lockie was going to a water management meeting in the afternoon! All indicates how complex water management and conservation is and how apparently well-intentioned actions can sometimes have adverse effects.

I suspect few boaters, of whatever length of experience, have access to the SCADA data and water modelling system that the lockies are guided by. The lockie who first asked us to wait had actually been sent an automatic message before he left home, telling him what he needed to do, based on the monitoring data and model.

Whilst some belittle the expertise at CaRT, as techie I tend to be impressed with the knowledge, skill and modern tools that the staff on the ground have at their disposal (which are improving all time so long as investment is available). I strongly suspect that they are able to take a much wider view of the system than an old style lengthsman who, as the name implies, only had a fairly limited view.

[mykaskin]

Number of times I pass a boat leaving gates open for me in my favor only to meet the next boat coming up behind them shutting all the gates and making everyone's life a misery. It's not difficult to close a gate once you're lock side, or a paddle once you're at a gate for that matter. If there is plenty of water about you can even half lift a paddle at the other end to help shut them and keep them closed - something the boater in front can't easily do...

On the southern GU it's usually one up one down due to lock spacing anyway, I often find I go to the effort of closing the gates to find someone coming up to the lock as I leave. There are exceptions to leaving the gates open - these include short non-river pounds where the lower lock leaks badly, and the top lock is a perfect fit as CRT have just replaced the gates before the other lock which really needs it... this has happened many times on the southern section...

The savings at lock 6 on the Atherstone flight are useful as many people moor in the town pound and upset normal level operation anyway.

I'd be careful using the sideponds on the Hanwell Flight as some of the paddles don't seal well any more, and can cause more water to be lost than they save. However this is down to poor maintenance.

Sidepounds = level with the canal when the gates are open

Sideponds = Not level with any navigational water level

But that's just my suggestion...

Mike

Edited May 4, 2017 by mykaskin

[Muddy Ditch Rich]

16 hours ago, Theo said:

Perhaps what I am going to say might be obvious but I will say it anyway.

1.  With leak free locks it is immaterial from a water conservation point of view whether gates are left open or shut.

2.  Leaving exit gates open will on average make locking more efficient because the lock will remain completely full or completely empty and there is the chance that the next boater will be able to go straight in.

3. With equal leakage at both ends closing up completely will reduce water loss by half.  This assumes that the rate of flow through the leaks is proportional to the water height difference.  After closing up the steady state will be  a half full lock which means that water will leak into the chanber at half the rate and out of it ditto.

Conclusion: Since CRT believe that the majority of boaters are enjoying the slow pace of canal boatiing rather than rushing to "get ahead" to catch the next cargo they are probably reasonable in asking us to close up at both ends.

Nick

 

Since closing gates was introduced by BW as an emergency measure to conserve water when the system was derelict and they had no intention of wasting any more money on it, CaRT cannot now claim both that it is well maintained and it is still necessary to close all gates.

While it makes little difference to those with multiple crew members, traveling single handed a 60 or 70 ft boat becomes exasperating if you have to stop and return to the lock to close both gates of wide locks. ( narrow gates can be strapped shut so don't really apply to this discussion) That is very hard to justify when you realise its often for no reason, then as you leave you may see the gates swing back open anyway.

 

[Dave123]

I was under the impression that generally bottom gates leak more, having a greater area for leaks to occur, and so if top gates are left open in many locations this will slowly drain the pound above? I agree in an ideal world with well maintained gates it would be easier and cause less wear and tear to leave them open but this is often not the case. On rivers it shouldn't matter, indeed on the river Wey gates are sensibly left open.

[Muddy Ditch Rich]

Leaving open as a rule may inspire CaRT to fix the leaks rather than force boaters to cover for their lack of maintenance  ?

Now I'm dreaming !

 

[Cleyley Bob]

On 5/2/2017 at 21:28, Mal in Somerset said:

I'll wait until then to book my appointment!!  I know they were all there last month!

 

Apologies for the late reply Mal in S. 

Went through last weekend and did a thorough check.

All the plastic 100m chainage marker boards are in place, including the double arrows at the centre point.

In my previous reply, I made an incorrect statement about the original cast iron imperial chainage numbers. All are in place - the plates in the relined section where re-affixed to the concrete rings - on the shoulder just above the timber rubbing strake.

[Mal in Somerset]

Maybe CaRT have been super efficient in replacing them but I fear it's probably me!!

 

[DHutch]

On 2017-5-2 at 10:19, billS said:

Minimises wear and tear on the gates and paddles.

And and means every other time you come to a lock it's already set for you.

Lock side cottage basement?

People and animals who fall in can swim out.

Certainly while I understand the many reasons for closing them and am happy to do so, it's not without draw backs.

Daniel

[Mal in Somerset]

On 2017-5-3 at 13:14, mykaskin said:

A few do: 

and here: 

 

I chatted with one of the inspection crew as we were coming down Atherstone flight earlier in the week. He said he would love to see the side ponds back in use but one of the things preventing this is that the tunnels between the locks and the ponds were originally wooden lined. The tunnels have now mostly been sealed up and the wood has largely rotted away, so to open them up is not the most simple job.

I was tempted to check out lock 6 but it has a sign saying only to be used by authorised personnel. When I spoke to the CaRT guy further down he said he would be quite happy for me to use it so long as I knew what I was doing, as in the above clip.

 

Edited May 14, 2017 by Mal in Somerset