The Perfect Narrow Lock

[RLWP]

I meant no cill visible. I assumed it would be possible with stronger modern building materials to have the cill directly under the closed gates? Am I being dense?

 

Afraid so. The cill is the bit the gate closes against at the bottom. So the cill takes the load from the water pressure, and seals the bottom of the gate.

 

Richard

[Guest Quo Vadis]

Suppose you had a mandate to design & build a narrow lock from scratch. Completely new. What would be your requirements for the design?

 

 

 

PLEASE!! Don't let James Dyson design it

[system 4-50]

I like the double bottom gates - looks iconic I think the basic design is pretty good really. Not sure what you could really do to improve apart from using more accurate, modern construction methods.

Gates with better sealing recesses to avoid leaks.

A barrier on the top gate that prevents a boat getting too near to the cill.

Perhaps a centralised paddle system that is easy to use and sends water evenly around the chamber.

I like the look of the double gates too, but then I want them both to open when I push the arm on one side. Some sort of lever linkage perhaps, underneath the chamber (for easy maintenance!!)

[Guest]

Afraid so. The cill is the bit the gate closes against at the bottom. So the cill takes the load from the water pressure, and seals the bottom of the gate.

 

Richard

 

I've argued this one before though and don't think I have been convinced of the answer -

 

Let's ask it another way - why does the cill have to protrude so far into the chamber. The gate seals at both sides and at the bottom and the middle. As long as the gate is sat on a concrete edge, which would need to be V shaped to match the gate profile why the need for all that bit 'inside' the lock - it's superfluous surely?

 

ed to add pic.

 

Edited November 15, 2011 by MJG

[journeyperson]

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.

Edited November 15, 2011 by journeyperson

[Josher]

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

 

[AJLintern]

How about fitting all boats with a large engine driven pump - you enter the lock, stick a large hose from the pump to the upper pound and pump out the chamber. Would save lots of water!

[journeyperson]

How about fitting all boats with a large engine driven pump - you enter the lock, stick a large hose from the pump to the upper pound and pump out the chamber. Would save lots of water!

 

and it could be used as a water canon if you became a victim of "lock rage". It would have to be a ****ing big pump if you didn't want to be there all day. Some people struggle with a windlass so heaven knows what chaos they would cause with a giant pump.

[Guest]

and it could be used as a water canon if you became a victim of "lock rage". It would have to be a ****ing big pump if you didn't want to be there all day. Some people struggle with a windlass so heaven knows what chaos they would cause with a giant pump.

 

Or to fend off 'gongoozlers' if they take the mick when you make a mistake...

[Bob18]

Hmm - like that idea, but every boat would have to be equipped...

(Not much fun if your boat is a "One Horse Power Special")

 

So why not have an 'odding great back pump on every lock to "hurl" the water back up the hill instead of tipping it down hill as we do just now? For an 8ft rise lock it "only" needs to shift about 30,000 gallons in three minutes up 8ft - don't you dare complain about the bye-washes on the Llangollen again

[system 4-50]

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.

Lets assume that you are designing the entire lock including approaches and landings, and also that it is a model lock for the redevelopment of all the locks on the (fictional) canal you are on, so you decide what ladders are on what sides.

 

I assume that double bottom gates would split the water-load into a force into the side of the lock (tending to keep the lock walls from falling inwards and therefore benign) and a force tending to tear out the end of the lock sides but only at half (?) the strength that would be presented by a single gate. Therefore in times of yore when the strength of building materials was more of an issue, double would be better than single.

At the top end the force down the lock sides would be held by the full length of the lock and therefore a single gate would be less of an issue?

Or is my antique "A" level Mechanics wrong?

[IanM]

Lets assume that you are designing the entire lock including approaches and landings, and also that it is a model lock for the redevelopment of all the locks on the (fictional) canal you are on, so you decide what ladders are on what sides.

 

I assume that double bottom gates would split the water-load into a force into the side of the lock (tending to keep the lock walls from falling inwards and therefore benign) and a force tending to tear out the end of the lock sides but only at half (?) the strength that would be presented by a single gate. Therefore in times of yore when the strength of building materials was more of an issue, double would be better than single.

At the top end the force down the lock sides would be held by the full length of the lock and therefore a single gate would be less of an issue?

Or is my antique "A" level Mechanics wrong?

 

Not sure that theory works as a single gate shuts against the non-quoin side too so you've still got the same forces acting on the same bits of stonework as double gates.

Edited November 15, 2011 by IanM

[Bob18]

With double gates there is a bit of force acting "into" the lockside as well as the obvious force pushing the end of the lock downhill. How much depends on the closing angle of the gates. Obviously this force might help to seal the gates, but I doubt if its of any significance in the grand scheme of the current leaky lock gate (top or bottom).

One drawback of double gates is that you have more bits to make water tight - two gate/quoin seals, two gate/cill seals, one gate/gate seal; compared with the single gate which has one gate/quoin seal, one gate/cill seal and one gate/wall seal.

 

I must admit that a well maintained double top gate is an attractive feature, but how many are in tip-top condition?

[carlt]

As I don't think the existing locks should be altered, for heritage reasons, and building a new canal to narrow dimensions would be a folly, there is no perfect narrow lock design, nor can there be, in my opinion.

[stewey]

A nice man or woman in a smart uniform who operates the lock for me and salutes as I leave. Then telephones the next lockeeper to let them know I'm on my way, cuts down the waiting time.

 

Ken

This is what we had on the River Weaver! Apart from the saluting, mind you!

 

Stewey

[Sir Nibble]

As I don't think the existing locks should be altered, for heritage reasons, and building a new canal to narrow dimensions would be a folly, there is no perfect narrow lock design, nor can there be, in my opinion.

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.

[Proper Job]

PLEASE!! Don't let James Dyson design it

What.........

 

Don't you want a lock that looks funky, is well marketed, you didn't realise you needed one until you got it, and then realise that it doesn't work as well as the good old tried and tested one that you got rid off??????????

 

Surely not

[RLWP]

It is certainly unlikely that a modern engineer would design a decent one

 

<snip>

 

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

 

Richard

[MartinClark]

A nice man or woman in a smart uniform who operates the lock for me and salutes as I leave. Then telephones the next lockeeper to let them know I'm on my way, cuts down the waiting time.

 

 

This is what we had on the River Weaver! Apart from the saluting, mind you!

 

 

This is what we had on the River Sarthe and River Mayenne in France, except on the upper Mayenne, where the lockkeepers look after several locks and whizz along on mopeds to get the locks ready for you.

 

This is very nearly what we had on the Grand Canal and River Barrow in Ireland, except the lockkeepers look after several locks and whizz along in little blue vans to get the locks ready for you.

 

In France and Ireland they phone ahead to tell the next lockkeeper that you are coming. No saluting, mind you.

 

Can't immediately think of any narrow locks with twin gates at the top end ?

 

Do you mean bottom end ?

 

You've not been on the Ashton Canal?

 

Lock 1:

 

Lock 2:

 

or the Bosley flight on the Macclesfield Canal?

[IanM]

Don't the narrow locks through the boat museum at Ellesmere Port have double top gates too?

[journeyperson]

Don't the narrow locks through the boat museum at Ellesmere Port have double top gates too?

 

Yes.

 

[fuzzyduck]

I think they should all be replaced with Caisson locks.

 

Adds to the adventure.

[carlt]

I think they should all be replaced with Caisson locks.

 

Adds to the adventure.

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

[mykaskin]

I'd consider automating the lock gates. The reasoning is:-

 

A fully loaded boat can only move about 20 tons. Add the cost of crew and it doesn't start to compete with road transport. If however you could make the boat robotic then it could move between locations under its own control and keep costs down. It also wouldn't be affected by the dark/fog so could potentially move 24/7. The only problem is the locks and these require manual intervention. If they were automated then the problem is solved. This would allow more freight back onto the canals and would help keep channels deep and wharves open. It would also allow much needed revenue to be earned.

 

Robotics don't work on a canal where there are non-robotic boats about...

 

I have single handed a loaded boat without problems through both narrow and wide locks. Automation generally slows things down, rather than make it quicker. That having been said, if it got the locks ready for entry it would save having a lock wheeler.

 

Something cross between Trent and Mersey locks, and the original design for Perry Bar. Double gates at the bottom please, unless you want extra expense making the lock a lot longer than needed as I normally need to hold the boat on the bottom gates to keep it well away from the cill (71.5 foot boat).

 

I usually use the top paddles to bring the boat to a stop in the lock, and the T+M locks work a treat (heading up to Stoke) allowing good control. For some reason the Oxford locks don't work so well (especially with an empty boat).

 

A long tail (at both ends) helps keep the boat in place while closing gates. The bottom of the Atherstone locks are perfect, I can close both bottom gates and jump on without stopping the boat.

 

The lock needs to be placed 7 foot out from the moorings, and have a good lead in with a metal rail. The mooring bollards need to be placed so that the boat can be strapped to a stop (using a band-end rail line), and then held in place close to the tail of the lock using said line.

 

Bottom gate balance beams need to be long enough to balance the gate, and give good leverage. Foot holds in the right place, but only needed to start the gate - not all the way around. A metal bar in the copings provide a foot hold for starting the gate closed. If a bridge is provided, make it far enough away to allow access with the gates open, and have a split for towing lines. If no bridge, good solid walkways, and railings placed to hold while you swing around the end of the gate to jump across to the other one.

 

If the lock needs a road access bridge on it's tail, ensure there is access down both sides (if possible). The towpath should pass through next to the canal.

 

Two gate paddles on the bottom, and two ground paddles on the top, with a gate paddle as well - 'cause I'm gready. Side-ponds these days are probably a good idea - but maybe with a special lock to stop idiots from using them wrongly!

 

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. As far as ideal wide locks go, you can't get much better than southern GU locks. Even Denham Deep isn't hard to operate. No gate baffles please though! :-)

 

Single top gate, with a rubbing plate that goes up to the top of the handrail, or ensure the handrail doesn't get caught by high bows. The walkway should be on the outside of the gate, not on top of it.

 

Ensure there is more depth over the cill (and floor) than needed for the boats that are using it. With a boat filling the width, there is only the depth to get the water to the other end of the boat.

 

Good quality old fashioned bricks, with stone coping seems to work better than nearly any other building material.

 

If the water supply is good, make the locks really deep (Cheshire Locks), or shallow enough to jump down on to the roof (Wolverhampton 21). Not half way between! :-)

 

Thats some of the things I like to see in a lock...

 

Mike

Edited November 15, 2011 by mykaskin

[Giggetty]

In no particular order:

Single bottom gates.

Balance beams that are not "knee scrapers" and properly balance the gate so it is easy to open once the water is at the correct level.

Proper stemming boards on both top and bottom gates - reduces the worries about being hung-up on or trapped under, a gate.

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

Properly installed, easily maintained seals on both hinge and opening end of the gates.

Decent working area clear of unnecessary obstructions and with a good non-slip surface - how many locks have "artistic lumps" and horrendously slippery slopes just where you are trying to put your feet, or a park bench in the middle of your natural walking path from one end to the other?

"Garrison Locks" style filling culverts - so nice to be able to wizz the paddles up quickly and not have the boat bounced from one end to the other.

Standard paddle gear, with sensible pawls that make that nice "click, click, click.." as you wind them up.

Little shop/bar accessible from the towpath/lockside - essential on those long hot summer's days to get an ice cream or a pint.

Proper landing stages (above and below the lock), with bollards, so if you are waiting in a lock queue you can moor up for a few minutes to visit the shop.

 

I'm sure there's more, and some are repeated from other's lists.

 

No discussion is complete without mention of the diagonal lock, which makes all the above points superfluous - see New style lock

Edited November 15, 2011 by Giggetty