The Perfect Narrow Lock

[soldthehouse]

I'm amazed nobody ever picked up on my "boat trebuchet" idea.

Go on then.......

[Ray T]

Fences to stop gongoozlers falling in!!!

 

 

(Sea lock at Arromanches-les-Bains)

 

 

[magpie patrick]

Not that I'm suggesting that this is a sensible idea, but if you really wanted a cill-less lock, just make the top gate as deep as the bottom one. Of course, you'd have to dig the upper level of the canal out to the depth of the lower one for a few yards before the lock, but that's all it would take. No more cilling.

 

I haven't read the rest of the thread, but that is how the Canal de Nantes a Brest Locks are constructed.

 

I'm always told by British Engineers "That won't work"...

[Ray T]

I'm amazed nobody ever picked up on my "boat trebuchet" idea.

 

Might save water

 

 

 

 

[RLWP]

Might save water

 

 

 

Your sling is far too short. The boat would end up going backwards

 

Richard

 

Now, how do I know that?

[magpie patrick]

It is certainly unlikely that a modern engineer would design a decent one, you don't win design awards with old technology. It would have to have power operation and whackloads of supervising electronics to be torn out in the first year to make it work.

 

Actually, here's an idea. Enter lock through top gate and close. Press button and chamber sides are retracted to make chamber wider and water lower. Open bottom gate and leave. Enter bottom gate and close, press button chamber sides are hydraulically moved back together, level rises.

 

That is basically how the nodding donkeys, sorry, Giant Kelpies, that got a grotesque amount of funding in Scotland are supposed to work

 

 

To our Scottish Friends, I'm sorry, I don't mind the idea, but the Big Lottery's decision to fund it was silly, and has probably cost them 20% of their budget

[Ray T]

Your sling is far too short. The boat would end up going backwards

 

Richard

 

Now, how do I know that?

 

 

Well yes Richard I realise the picture is not perfect, something I cobbled together before anyone else did.

 

Don't tell me you are / were a science teacher!

Edited November 15, 2011 by Ray T

[fuzzyduck]

I'm amazed nobody ever picked up on my "boat trebuchet" idea.

 

I think you must be onto something, it looks like your proposition has been erased from the forum. The man is depriving you of proper recognition.

[soldthehouse]

Your sling is far too short. The boat would end up going backwards

 

Richard

 

Now, how do I know that?

I dont know how do you know that?

[mykaskin]

I haven't read the rest of the thread, but that is how the Canal de Nantes a Brest Locks are constructed.

 

I'm always told by British Engineers "That won't work"...

 

You could just make the canal so deep that you never get near the cill. I was coming down Hunts lock, which is actually quite tight for a full length narrowboat (the short lock, not the long one!), and was worried about the cill. The lock keeper said it shouldn't worry me being, something like, 12 foot below top level, and the lock is only about 8 foot drop...

 

Many narrow locks have a very small cill, but the easiest way to stop any cilling is leave the boat in forward gear against the bottom gates. If they are double gates, just push against the boat, open them, and the boat comes sailing out on it's own.

 

Mike

nb. Roboticboatsrus

Edited November 15, 2011 by mykaskin

[Clive B]

Bollards........lots more bollards!

[Bob18]

But not too many, and properly fixed in the ground, I've a) Fallen over too many, and Pulled too many up over the years.

[alan_fincher]

 

You've not been on the Ashton Canal?

 

I only said I couldn't think of one.

 

I've never been on a canal north of about Anderton, so I plead fully guilty to being a Southern boy on such matters.

 

Thanks for educating me!

[nicknorman]

 

The GU locks have overflows in the ground paddles, which if the bottom gates are closed, and water tight, will fill the lock up rather than waste the water around a bywash. Not seen this on a narrow lock though.

 

Having just done Perry Barr locks I can tell you that they are like that. Having just done them after heavy rain, I can tell you that overflows that lead into the Lock chamber are a pain -the rate of flow into the lock matches the rate of flow out of the open bottom paddles before the lock is empty, resulting in a very long wait for the final few inches of drop and/or level never being reached so great force has to be applied to start the gate.

 

And since on arrival at the top to descend, every lock is full and every pound is full, each lock drains into an already full pound at a rate greater than the bywash can cope with, so each pound floods the towpath making walking ahead a soggy experience (very soggy if you fail to notice where the submerged edge of the towpath is!). Having bigger bywahes would improve this problem but make the former problem worse. Better with bywashes that bypass the lock altogether and can cope with high flow.

[alan_fincher]

I see you've been through the staircase lock on the Droitwich canal then

Ah,

 

The only lock that I have so far seen where a boat seemed to manage to get caught and stuck going up rather than down!

 

I don't know if it was a cost saving measure, but otherwise the designers of most of the new Droitwich narrow locks would have done well to study existing locks, (like the ones nearer the W&, and appreciate that the apron approaches to such locks are usually made that "funnel" shape for a reason.

 

Give the lock a tapering approach, and even a poor steerer on a windy day will probably get in with nothing worse than a bit of blacking taken off.

 

Some of those locks have been given "hard corners" which after a few months use have already started having lumps of concrete smashed off where people have cocked up their final approach. No doubt there are also some boats already that have matching dents!

 

Having just done Perry Barr locks I can tell you that they are like that. Having just done them after heavy rain, I can tell you that overflows that lead into the Lock chamber are a pain -the rate of flow into the lock matches the rate of flow out of the open bottom paddles before the lock is empty, resulting in a very long wait for the final few inches of drop and/or level never being reached so great force has to be applied to start the gate.

Yes,

 

Even on the Southern GU that Mike Askin says he favours for wide lock design, if there is too much water coming down a flight, it can be a real struggle to get bottom gates open.

 

Recently the approach at places like Stoke Bruerne or Buckby seems to just push a lot of water down from the top, as the easy way to ensure everything is full, (despite frequent requests not to waste water). I'd say this method of (not really) managing the pounds has made recent passages through these flights a lot harder on a bad day. And yes we have seen completely flooded and waterlogged towpaths there too, when it can't even flow over the gates without spilling on to the banks too. (I used to think of Stoke as a "doddle" - lately it has been hard work, and I don't think that is just me getting older! ).

[Maffi]

snip

Single sided operation, so you don't have to cross the lock (very useful for single handers).snip

 

£40,000 it cost to electrify the lift bridge at Thrupp to 'make it easier for single handed boaters' (BWs words) and I am yet to see a single hander who has the slightest idea how to use it.

 

Also, with single bottom gates, if you are single-handed you would find yourself doing more walking around the lock if the balance beam isn't on the same side as the lock landing when you want to close the gate after exiting - and you can bet there would be no consistency about that, or lock ladders. I think if single bottom gates were a good idea they would have been used in the first place.

Banbury has the last double bottom gate on the Oxford Canal all the rest down to The Thames are single gates.

 

How about some sensors built in to the wall at different levels, with an auto stop if the boat goes out of level?

 

Oh you mean like 'Paying attention sensors' I think they are called eyes.

[john6767]

£40,000 it cost to electrify the lift bridge at Thrupp to 'make it easier for single handed boaters' (BWs words) and I am yet to see a single hander who has the slightest idea how to use it.

 

I studied that when we went through in August. I failed to see how having a control box on each side actually helps, both sides seemed perfectly accessible so I would have thought one control box would have been adequate. Am I missing something?

 

 

 

[Theo]

are not single gates at both ends out too, I remember asking about this on here before and the two gates at the top are required for strength against the weight of the water in the pound.

 

South Stratford has single bottom and top gates. Bottom gate can be very heavy though.

 

Nick

[TimD]

Finally got to entry #66 before someone pointed out Banbury to Oxford has single gates at both end. The museum at Banbury claims the resaon was they had to finish the stretch to the Thames quickly due to the plans to open the GU. I didn't find the single lock gates any heavier than mitred gates, it is more a function of how impatient you are. Badly balanced gates and beams too low make a much bigger difference.

 

Back to the ideal single lock:

no leaking gates/paddles.

A decent narrow channel at both ends makes a huge difference to both single handing and dropping off, picking up crew.

Steps down at the lower end of the lock before any bridge.

Safe means of crossing on the gates at both ends (if no bridge at lower end)

Paddles that operate without having to use my 90Kg body weight to turn the windlass and ones that don't send a fountain of water up your legs.

Bywashes set so you don't get water flowing over the gates (eg unlike Todmorden, Sowerby Bridge)

Ideally I'd like the gates to automatically slowly swing closed, but with some kind of prop to keep them open. This would mean that single handers can leave the locks with gates open, they will swing shut after a couple of minutes, If you are setting a lock in advance (in a flight) you can open the gates and know it will stay open.

On narrow locks with mitre gates they could be mechanically connected so pushing against one gate will open both, pushing from both sides would be the same as now.

Ladders with enough room for size 11 shoes and without loose grab rails that give you a heart attack.

Non-slip lockside surface but still looks like stone so it's still as pretty.

[Maffi]

I studied that when we went through in August. I failed to see how having a control box on each side actually helps, both sides seemed perfectly accessible so I would have thought one control box would have been adequate. Am I missing something?

It is a change over bridge. The mooring for the towpath is on opposite sides of the canal bridge. You moor up and operate the bridge from that side. You then take your boat through the bridge moor on the opposite side of the canal and close the bridge from the other consul. Cross the bridge to collect your key. It doesn't work unless you read the screen to see when the bridge is fully up because until the screen says the bridge is up, irrespective of the reality, the other consul is locked out.

 

Of course pre-mod anyone could operate the bridge now only those with a key can do it and funnily enough not all boaters have one.

 

Edit: Remember the safety rail around the village side consul is cheap and nasty and should not be climbed on.

Edited November 17, 2011 by Maffi

[Maffi]

Finally got to entry #66 before someone pointed out Banbury to Oxford has single gates at both end. The museum at Banbury claims the resaon was they had to finish the stretch to the Thames quickly due to the plans to open the GU. I didn't find the single lock gates any heavier than mitred gates, it is more a function of how impatient you are. Badly balanced gates and beams too low make a much bigger difference.

 

I bet you had trouble with the single bottom gate at Shipton lock.

[Duchess Omnium]

£40,000 it cost to electrify the lift bridge at Thrupp to 'make it easier for single handed boaters' (BWs words) and I am yet to see a single hander who has the slightest idea how to use it.

 

 

Banbury has the last double bottom gate on the Oxford Canal all the rest down to The Thames are single gates.

 

 

Oh you mean like 'Paying attention sensors' I think they are called eyes.

 

I think I know how to use the lift bridge at Thrupp -- because Maffi showed me, my first single handed run. Thanks!

[Maffi]

I think I know how to use the lift bridge at Thrupp -- because Maffi showed me, my first single handed run. Thanks!

Did I? Good Lord memory not what it used to once was be.

[DandV]

All holes in the lock sides connected with the sluice culverts so as to create an automatic boat wash when raising the paddles. bizzard.

And install sluice driven rotary brushes on spring loaded arms with detergent dispensers to give the top sides and available crew a wash and scrub at the same time!

 

Cheers rub a dub Don

[Tiny]

Take a standard shroppie narrow lock with top gate paddle, water entires to the lock designed no throwforward (like that coming uphill on Heartbreak). Have two ground paddles top and bottom.

Put skinny gates on it so it does not attack boats as many fat shroppies top gates with their sharped edged metal do. Chuck in a crossing bridge at the bottom (like those on the T&M) and a long exit narrow section at the top to wait in while closing the top gate (like Tardibigge).

At the bottom end angle the weir stream down rather than across the canal and give the lock a long entry narrow with steps both sides to boat level so people can get on and off easily.

Have 4 ladders - two each end in the lock and one bollard on the offside for use in the locks with a metal edge for the rope to slide along rather than grinding on a rough stone one.

Have at least 8 bollards top and 8 bottom for mooring and waiting for the lock to be prepared before entry. Make the lock approx 7 feet deep.

Get the owners of the lock (CART, BW, EA) to keep all parts in full working order greased with waterproof silicon grease as necessary and easy to use.

 

Make the pounds between the locks wide enough and long enough for boats to pass easily.

Edited November 18, 2011 by Tiny