The Perfect Narrow Lock

[system 4-50]

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

 

Let the context be:

You have reasonable but not unlimited funds for the build.

You have to keep it broadly in character with original locks.

The result must be at least as reliable and long-lasting as original locks.

It must be very low and simple maintenance. (So probably no electrically-powered components then.)

It is to include any improvements that modern engineering can provide.

 

I'd like:

Only one gate at each end.

Water movement such as to give minimal charging forward and back.

Leaving gate open on leaving to be normal practice

No cill

No possibility of catching buttons on going up or down.

Some automatic mechanism which keeps the lock full when it is full and empty when it is empty so that I don't have to fiddle with paddles for 3".

 

and there's more

[alan_fincher]

I'd like:

 

Some automatic mechanism which keeps the lock full when it is full and empty when it is empty so that I don't have to fiddle with paddles for 3".

 

Why is that necessary if you have.....

 

Leaving gate open on leaving to be normal practice

 

Think about how you can realistically have upper gates without a cill.

 

(Clue: Generally you would be daft to try.)

[Liam]

I find the 'usual' design that's been used on the inland waterways over the past 250 years or so to work quite well so I'll stick with that

[Guest]

Why is that necessary if you have.....

 

 

 

Think about how you can realistically have upper gates without a cill.

 

(Clue: Generally you would be daft to try.)

 

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.

[IanM]

No cill

 

Good luck with that bit

[AJLintern]

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.

[David Mack]

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.

 

Really??

 

Apart from a few exceptions like Bosley, virtually all narrow locks have single top gates!

 

And the load on bottom gates is higher than top gates since they retain a greater height of water.

 

David

[Chalky]

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.

[alan_fincher]

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.

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

 

Do you mean bottom end ?

 

(Something like Somerton deep is single gates both ends, and anyway a single gate at either end of a narrow lock is surely doing no more than a double gate on a broad one, being similarly sized ?)

[IanM]

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.

 

That's more or less a railway isn't it?

[Guest]

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

 

Do you mean bottom end ?

 

(Something like Somerton deep is single gates both ends, and anyway a single gate at either end of a narrow lock is surely doing no more than a double gate on a broad one, being similarly sized ?)

 

Yup got my ends mixed up..

 

(Something like Somerton deep is single gates both ends, and anyway a single gate at either end of a narrow lock is surely doing no more than a double gate on a broad one, being similarly sized ?)

 

That was my argument I'm sure when I asked at the time but it was refuted...

 

EDIT TO AD - the argument IIRC was that the strength is in the fact that they meet at an angle and thereby are stronger.

 

Really??

 

Apart from a few exceptions like Bosley, virtually all narrow locks have single top gates!

 

And the load on bottom gates is higher than top gates since they retain a greater height of water.

 

David

 

See above..

Edited November 15, 2011 by MJG

[classicstove]

Would always have water coming from the top end paddles enterin the lock in several places so there is little turbulence and that it would also shut the bottom gates (prefer two) on lifting of the top paddle on the same side (like Perry Bar and Garrison)

 

Also, need to think about side pounds so water is used efficiently

[Nine of Hearts]

Think about how you can realistically have upper gates without a cill.

 

(Clue: Generally you would be daft to try.)

 

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.

[Guest]

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.

 

How heavy would the gates be though??

[Nine of Hearts]

How heavy would the gates be though??

 

Same weight as the bottom ones, in fact slightly lighter as they'd always be fully submerged when you operated them. The bottom ones are only ever half under water when they're being moved.

[bizzard]

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

[alan_fincher]

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.

 

Yes - it is possible.

 

It would probably guarantee that top gates leaked as much as bottom ones, (traditionally it is less on top gates, for gates that haven't actually got holes in, because the "length of the join" is shorter).

 

Also when you "got something behind the top gates" when open, or something lodged blocking the cill and stopping them closing, you would need a massive "keb" or similar to be able to reach down that far, (all of it through water). Similar problems on bottom gates can be dealt with when the lock is empty, and, provided one can be got into position, from a boat, if it helps.

 

I suspect the resulting sump might quickly start to get filled with debris too, and cause additional problems.

[Nine of Hearts]

Yes - it is possible.

 

It would probably guarantee that top gates leaked as much as bottom ones, (traditionally it is less on top gates, for gates that haven't actually got holes in, because the "length of the join" is shorter).

 

Also when you "got something behind the top gates" when open, or something lodged blocking the cill and stopping them closing, you would need a massive "keb" or similar to be able to reach down that far, (all of it through water). Similar problems on bottom gates can be dealt with when the lock is empty, and, provided one can be got into position, from a boat, if it helps.

 

I suspect the resulting sump might quickly start to get filled with debris too, and cause additional problems.

 

Correct on all counts, which is why it is a foolish idea. What is wrong with cills, anyway? I'm now thinking of an auto-flume idea which I'd probably never get past the safety guys. Shame.

[Bob18]

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.

[David Mack]

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

 

[Sir Nibble]

An ordinary lock properly maintained with operating moorings (Basingstoke take note) and a general presumption for leaving gates open (BW take note). Also, fitting reduction gears to overcome stiffness from deterioration and lack of maintenance to be banned.

[journeyperson]

Single bottom gates would mean making the lock longer wouldn't it, to accommodate longer boats? I think the existing design was already well thought out for ease of use and low maintenance and would be hard to improve upon.

 

New locks make use of concrete and prefabrication which should be stronger and less likely to move, but you can't beat brick and stone for aesthetics.

 

 

[KenK]

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

[mayalld]

Good luck with that bit

 

 

It isn't impossible to build a lock that has no protruding cill.

 

You simply build the chamber some 10 feet longer, and fit tall (lower gate style) gates 10 feet downstream from the "step", with a cill at invert level

[system 4-50]

Why is that necessary if you have.....

 

 

 

Think about how you can realistically have upper gates without a cill.

 

(Clue: Generally you would be daft to try.)

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?