Narrow bottom lock on Llangollen Canal?

[mango]

To measure the width of a boat you need a Lancaster Bomber to overfly your boat at night and use a combo of two searchlights lights and a person looking down a sightpiece comprising a long piece of wood with two pegs a set distance apart. Then a clever bloke to do the calculations.

 

With a set square couple of pieces of tall timber and one of those lazer things Estate Agents use to measure walls will do away with a tape measure.

It is always encouraging to learn of alternative approaches to solving everyday problems. Your flight of fantasy does suggest you might be related to Bizzard.

[mango]

 

 

Don't you think that's missing the point - your mate is convinced his boat is 6 foot 10 wide, the only sensible warning is "this lock is only suitable for boats 6 foot 10 wide" at which point he would have tried to go through it.

 

I'm quite happy for that warning to be given, but it won't help if you don't know how wide your boat is!

 

And as you raise it, yes I do think people are expecting too much: I read posts warning of levels a couple of inches down, or asking for similar information, a desire to plan to nth detail and also a desire (in this case) for standardisation that just doesn't exist. If you don't know the history the canal system appears erratic (in fact, it does even if you do know the history) - that needs to be accepted.

 

Canals don't have much flow, but it's still good to go with it

 

But the HNBOC presumably also realise that some narrow locks were built narrower in the first place

I agree with your post.

 

One small point. It was Narrow Boat Owners Club and is now the Historic Narrow Boat Club. I guess the boats have got older and the owners wider.

[David Mack]

One small point. It was Narrow Boat Owners Club and is now the Historic Narrow Boat Club.

When the club was founded the only narrow boats were historic ones. The H was added a few years ago to distinguish the club's interest from the built-for-pleasure NBs. The O was dropped when the club changed its rules so that anyone could become a full member.

[mango]

When the club was founded the only narrow boats were historic ones. The H was added a few years ago to distinguish the club's interest from the built-for-pleasure NBs. The O was dropped when the club changed its rules so that anyone could become a full member.

Thanks for this information David and please forgive me for making a facetious comment. I appreciate the importance of looking after and using historic boats.

[StarUKKiwi]

We also got stuck and had to be towed out of Hurleston, no fenders down, but is wide just behind the cabin bulkhead. We have heard since that two bolts either side and a chain tightened, will pull the sides on enough to get you in

We also got stuck and had to be towed out of Hurleston, no fenders down, but is wide just behind the cabin bulkhead. We have heard since that two bolts either side and a chain tightened, will pull the sides on enough to get you in

[vicafloat]

CRT shaved some of the brickwork at the top of the lock last winter, and I believe this has helped. But as another OP has

already mentioned,some people will insist on leaving fenders down;if they do they will get stuck!!

[ditchcrawler]

I got stuck with the fenders down one side. As a rule I never boat with fenders down, but I had moored overnight just below the lock I pulled away and went straight round into the lock and failed to lift them. I felt it bind and was able to sort things before we jammed solid.

[magpie patrick]

In Landscape With Canals Rolt records how he greased Cressy's hull and planed obvious high spots off (I think this was actually at Grindley Brook) before backing her up and entering the lock at full tilt, and his awareness that if this approach didn't work, nothing short of demolishing the lock would have got her out again

[FadeToScarlet]

In Landscape With Canals Rolt records how he greased Cressy's hull and planed obvious high spots off (I think this was actually at Grindley Brook) before backing her up and entering the lock at full tilt, and his awareness that if this approach didn't work, nothing short of demolishing the lock would have got her out again

They were real men in those days..........

[chrislyn]

we also got stuck in the bottom lock and had to be pulled out.....twice...turns out 6'10" is a nominal width used by boatbuilders and ours 'bowed out' in the middle and was 7'1" at her widest! long (and often repeated) story, but we insisted our builder (famous North West boatbuilder, now no more) built us another, as we purchased with the intention of cruising the whole system and if we couldn't get up the Llangollen then we couldn't do that.

[Mike Todd]

Some people really don't get irony, do they? Even with the addition of smileys...

 

I've understood real -- as opposed to theoretical -- engineering since trying to fit shelves to a wall when I was about ten. Walls aren't always flat or vertical, alcoves don't have parallel sides, shelves don't always end up level front to back. Having looked at quite a lot of them over the years, locks are much less ideal than house walls.

 

Incidentally, my job title is Chief Engineer. I didn't get that by designing things that work in theory but not in practice, allowing for real imperfections is simply part of good design. So please don't patronisingly assume all engineers are head-in-the-cloud theorists -- I think you might be confusing us with scientists... ;-)

No, the confusion is with architects (cf structural engineers!)

 

Also, the unevenness means that it is possible (theoretically!) for a boat less than full length to be able to ascend or descend successfully at one position in the lock and not in another. This may also explain some of the apparently inconsistent evidence being cited.

Edited August 6, 2014 by Mike Todd

[IanD]

No, the confusion is with architects (cf structural engineers!)

 

Also, the unevenness means that it is possible (theoretically!) for a boat less than full length to be able to ascend or descend successfully at one position in the lock and not in another. This may also explain some of the apparently inconsistent evidence being cited.

Indeed it might. Which is one reason I suggested it would be a great idea if CRT had an accessible database of "narrow lock" profiles, preferably on their website. If you had a profile of your boat (in a simple agreed format e.g. maximum width at intervals along the hull) it would be relatively simple for software to calculate which locks fell into which categories for your boat:

 

1. green = OK regardless of position

2. amber = should be OK in some positions but not others (could suggest which e.g. "OK if kept towards top of lock", "avoid bottom end of lock")

3. red = you're not going to make it

 

You wouldn't even have to know which locks to check, it could check your boat against all the locks and tell you which ones were "red" and "amber". If you were really thinking about how to do this the site would also store your boat profile, so if you provided an email address or sms number and CRT found that a lock had narrowed and updated the lock profile, you could be automatically warned that you might no longer fit through it.

 

Of course such a useful example of how to take advantage of modern technology is pretty unlikely to happen...

[Paul C]

Indeed it might. Which is one reason I suggested it would be a great idea if CRT had an accessible database of "narrow lock" profiles, preferably on their website. If you had a profile of your boat (in a simple agreed format e.g. maximum width at intervals along the hull) it would be relatively simple for software to calculate which locks fell into which categories for your boat:

 

1. green = OK regardless of position

2. amber = should be OK in some positions but not others (could suggest which e.g. "OK if kept towards top of lock", "avoid bottom end of lock")

3. red = you're not going to make it

 

You wouldn't even have to know which locks to check, it could check your boat against all the locks and tell you which ones were "red" and "amber". If you were really thinking about how to do this the site would also store your boat profile, so if you provided an email address or sms number and CRT found that a lock had narrowed and updated the lock profile, you could be automatically warned that you might no longer fit through it.

 

Of course such a useful example of how to take advantage of modern technology is pretty unlikely to happen...

 

Its a great solution, but one for a problem that doesn't really exist. We don't hear many stories of boats getting stuck in locks*, EXCEPT for Hurleston and EXCEPT for older and/or ex-working boats where they are definitely more than 7' or so due to spread. The only other I can remember in my local area, was a boat stuck in Cholmendeston lock, and that was because the boat was definitely too wide, it had its bottom replated and they never cut off enough of the plate, so it was something like 7'2". I vaguely recall a few other boats stuck but I think these fall into the old/working boat category. And they have a list of tight locks, which is a reasonable system in place already.

 

* Except for when boaters daftly leave fenders down.

[magpie patrick]

Indeed it might. Which is one reason I suggested it would be a great idea if CRT had an accessible database of "narrow lock" profiles, preferably on their website. If you had a profile of your boat (in a simple agreed format e.g. maximum width at intervals along the hull) it would be relatively simple for software to calculate which locks fell into which categories for your boat:

 

1. green = OK regardless of position

2. amber = should be OK in some positions but not others (could suggest which e.g. "OK if kept towards top of lock", "avoid bottom end of lock")

3. red = you're not going to make it

 

You wouldn't even have to know which locks to check, it could check your boat against all the locks and tell you which ones were "red" and "amber". If you were really thinking about how to do this the site would also store your boat profile, so if you provided an email address or sms number and CRT found that a lock had narrowed and updated the lock profile, you could be automatically warned that you might no longer fit through it.

 

Of course such a useful example of how to take advantage of modern technology is pretty unlikely to happen...

 

On the Coal Canal we have had one of the locks surveyed by students, using rotating lasers that each do a 360 degree survey (the only gap is the shadow below the laser, everything else is covered in 3D). It took a morning to survey one lock (3 or 4 different locations to remove shadows - the equipment can't see behind items) and about 24 hours later it was all stitched together. They are gradually going to do the whole canal for us.

 

Do this for every lock, and for every boat, and write some software to "drive" the virtual boat into the virtual lock, and bob's your uncle

 

The thing is we get this for nothing, because it's a student project, and it will take a couple of years to get ten miles of canal and 22 locks done. Of course you could pay for it, but this would entail a lot of staff time and the staff would be using tens of thousands of pounds worth of equipment and software, to survey around 900 locks and 20,000 boats. Any guess as to the cost?

 

And to solve what? the vast majority of boats get through the vast majority of locks without a problem, and I'll bet the vast majority of occasions a boat sticks it's either because of fenders or debris. For the few boats that won't fit through the few locks that won't take them, the owners have some idea. I'm pretty certain Juno would struggle at Hurleston as she often can't quite get through only one gate on the K and A.

 

Boats jamming in locks, that owner was blissfully unaware they might jam in, is incredibly rare.

[system 4-50]

Now if we had the scanning hardware on every boat, we could detect locks "breathing", and even be able to forecast when they were going to collapse!

[dmr]

Boating has an element of uncertainty and adventure, that's why its wonderful and I hope it stays that way.

Should we map the entire system for depth and update it in real time everytime a new shopping trolley gets thrown in!

 

(speaking as someone who can only get thru Hurleston backwards!)

 

.............Dave

[IanD]

If it's not a real problem then there's no need for a solution -- but that's not the impression I got from earlier discussions about wide boats and narrow locks...

 

Technology's great but not when it's a solution looking for a problem -- like Internet-connected toasters and fridges

[mayalld]

Indeed it might. Which is one reason I suggested it would be a great idea if CRT had an accessible database of "narrow lock" profiles, preferably on their website. If you had a profile of your boat (in a simple agreed format e.g. maximum width at intervals along the hull) it would be relatively simple for software to calculate which locks fell into which categories for your boat:

 

1. green = OK regardless of position

2. amber = should be OK in some positions but not others (could suggest which e.g. "OK if kept towards top of lock", "avoid bottom end of lock")

3. red = you're not going to make it

 

You wouldn't even have to know which locks to check, it could check your boat against all the locks and tell you which ones were "red" and "amber". If you were really thinking about how to do this the site would also store your boat profile, so if you provided an email address or sms number and CRT found that a lock had narrowed and updated the lock profile, you could be automatically warned that you might no longer fit through it.

 

Of course such a useful example of how to take advantage of modern technology is pretty unlikely to happen...

I suspect that the issue would be that you are actually looking at a very complex mating of two irregular 3D objects that will move relative to each other providing certain coinciding pinch points are missed.

 

Knowing the profile of the lock isn't enough. You need to know the profile of the boat as well.

 

To take a hypothetical example;

 

A full length boat is 6'10" all along, except that it is 6'11.5" at the rubbing strake 20' back from the stem post a foot above the normal water level.

 

It intends to pass a lock that is a minimum of 7' wide, except that 40' from the bottom gates between 11" and 12" from the lower level it has a small bulge that reduces the width at that point to 6'11"

 

Any advice on passing the lock would be specific to that boat (the boat will descend with no issue and there are at least 2 ways of passing up it)

 

As most people don't accurately know the width of their boat at all points it wouldn't be very workable.

 

And that is before we factor in the question of liability if a boater follows advice and comes to grief.

[IanD]

Which is why I said you'd need your boat profile -- presumably measured using the wood-and-laser-pointers method -- in which case it becomes a simple programming problem.

 

But it seems there's no need for such an application because everybody who needs to know which locks are narrow already knows -- hoorah

[MtB]

Which is why I said you'd need your boat profile -- presumably measured using the wood-and-laser-pointers method -- in which case it becomes a simple programming problem.

 

But the boat is as complex a shape as the lock sides. a 3D shape. You seem to constantly overlook this.

 

Your wood and laser method won't even come close to mapping the shapes of each side of my riveted iron boat.

 

Typical solution from an engineer who only flies a desk.

 

 

MtB

[IanD]

Keep throwing insults, it's a really good way to make people see the forum as a friendly place to be

[MtB]

Keep throwing insults, it's a really good way to make people see the forum as a friendly place to be

 

 

Your arsey comments earlier in the thread about how easy it is to measure the width of a boat were hardly friendly

[IanD]

Nobody apart from you seems to have taken offence, and the only insults I can see are several from you accusing engineers -- other than you, of course -- of being impractical desk-jockeys.

 

Perhaps you should take the log out of your own eye before accusing other people of unfriendly postings?

 

Or perhaps you might consider making some constructive and/or helpful postings instead of negative ones? Oh I forgot, it's much easier to criticise

[MtB]

You clearly don't spend much time here reading anything other than your own posts, or you'd realise I spend quite a bit of time writing constructive posts to help other people.

 

My posts which you percieve as unfriendly are just me handing back some of what you started dishing out earlier.

 

MtB

[IanD]

You're the one who labelled engineers as theoretical desk-jockeys (several times). Please point out anywhere I dished out a similar insult, and I'll apologise.