Strapping Gates

[ditchcrawler]

Having seen it done a few times by skilled boaters, not something I would attempt I thought that strapping the top gate closed as you came into a lock was a traditional practice. But it seems that on the Thames and Severn canal it was against the rules and boaters got find for doing it if caught in the act.

[MtB]

1 hour ago, ditchcrawler said:

Having seen it done a few times by skilled boaters, not something I would attempt I thought that strapping the top gate closed as you came into a lock was a traditional practice. But it seems that on the Thames and Severn canal it was against the rules and boaters got find for doing it if caught in the act.

 

Perhaps it was because it was such a regular practice, that the T&S needed a bye-law and a fine to stop boaters doing it. 

 

One wonders why they were so set against it being done. Probably one of the directors had a bee in his bonnet about it. 

 

 

 

 

[Mike Tee]

Maybe a minority were a bit exuberant regarding speed coming in, which must eventually damage the gate.

[MtB]

2 minutes ago, Mike Tee said:

Maybe a minority were a bit exuberant regarding speed coming in, which must eventually damage the gate.

 

 

In which case one wonders why this was a problem for the T&S, but not for any other canal...

 

 

 

[Ken X]

As a mere bystander who has strapped a top gate occasionally, it occurs to me that if said canal company fitted strapping posts to their gates, it shouldn't be a surprise if people used them.  They seem to be a rare beast these days which discourages the practice somewhat. 🙂

[dave moore]

There are still plenty of top gates with strapping posts, for me the problem is that the vertical part of the handrail is now often so close to the post that it’s not easy to flick the strap over. I’ve not done it fora long time, sadly….but it’s a prime example, to me, of

” let the boat and water do the work “…. how it was often done way back when.

[Mike Tee]

4 hours ago, MtB said:

 

 

In which case one wonders why this was a problem for the T&S, but not for any other canal...

 

 

 

Maybe it was, but they were prepared to put up with it! Who knows, maybe some highly placed incompetent at the T & S saw somebody doing it, didn’t understand, took nobody’s opinion, and just banned it as it appeared to be heavy handed / lazy etc.

[Derek R.]

Those who knew how to work a lock efficiently would also know that when strapping a top gate closed, it was necessary to have a bottom paddle drawn as the gate was half way closed to prevent excessive strain in the top gate by the compression of water mass within the lock. An 'Old boy' lengthsman on the Wolverhampton flight showed us 'the way' back in '83.

[magpie patrick]

On a busy profitable canal anything that wears the infrastructure is accepted as the price of keeping traffic moving - if gates need replacing a year or two earlier so be it, the abuses are getting traffic on it's way faster and maintaining profitability.

 

On a less used, less profitable canal avoiding wear and tear may be paramount, what we don't know is what went with not strapping boats to stop them, but we can be fairly certain it didn't involve hitting the bottom gates with a thwack. More likely the boats were carefully roped in and out and the whole operation was more bucolic. 

 

I suspect (although @Pluto might know more) that early lock operation on early canals, and the T&S was relatively early, was probably a relaxed affair until they got busy and/or until the railways started competing.  

[ditchcrawler]

16 minutes ago, magpie patrick said:

, but we can be fairly certain it didn't involve hitting the bottom gates with a thwack.  

They fine them for that as well

[IanM]

Bear in mind that the Thames and Severn was a wide canal used by wide barges, the consequences of something going a bit wrong when strapping a boat was increased.  The canal company was always a bit precious about their canal anyway.

 

Also, can you even strap a boat when a lock has double gates?  In a narrow lock the gate will stop against the masonry of the lock side.  With a wide lock it will be the cill taking the brunt of the force.

[MtB]

30 minutes ago, IanM said:

Bear in mind that the Thames and Severn was a wide canal used by wide barges, the consequences of something going a bit wrong when strapping a boat was increased.  The canal company was always a bit precious about their canal anyway.

 

Also, can you even strap a boat when a lock has double gates?  In a narrow lock the gate will stop against the masonry of the lock side.  With a wide lock it will be the cill taking the brunt of the force.

 

 

I think you have probably hit on the reason. If it's a wide canal, any attempt to do it is going to be both pointless and risk serious damage to the gate being strapped. Obvious now that you've pointed it out! 

[Pluto]

They certainly strapped boats into locks on the L&LC, with cast iron bollards provided, Unfortunately, the wear caused considerable grooves to appear, often forming sharp edges. On the 4 August 1939, the strap rope used a boatman on the Wharfe whilst descending Wigan Locks caused the damage seen below. Strapping using the lock gates is not mentioned in the 1875 Byelaws.

I do recall a similar event on the MSC when a vessel lost power whilst entering one of the locks. They did try to stop the boat by a strap rope, but that snapped as a result of internal friction heating the rope so much that it melted.

[ditchcrawler]

54 minutes ago, IanM said:

Bear in mind that the Thames and Severn was a wide canal used by wide barges, the consequences of something going a bit wrong when strapping a boat was increased.  The canal company was always a bit precious about their canal anyway.

 

Also, can you even strap a boat when a lock has double gates?  In a narrow lock the gate will stop against the masonry of the lock side.  With a wide lock it will be the cill taking the brunt of the force.

Sounds good, thanks, not something I considered 

[Pluto]

5 hours ago, IanM said:

Also, can you even strap a boat when a lock has double gates?  In a narrow lock the gate will stop against the masonry of the lock side.  With a wide lock it will be the cill taking the brunt of the force.

That is a little simplistic. With a single gate, when a boat hits, all its force is on the top frame of the gate, so acting on the wood's weakest direction. With mitre gates, the forces are split, with some being in the same direction as with a single gate, but a significant amount goes into the lock side. Forces on the sill act in a similar fashion, only they are also fixed to the stonework or concrete of the sill.

I would suggest that strapping on a wide lock would not be effective as it would cause the boat to hit the lock side with greater force than if strapped from the lock side. Even then, this caused significant damage, still visible on many L&LC locks. The photo shows the wear on Wigan Top Lock from a lifetime being hit by loaded boats being strapped into the lock. Strapping on mitre gates would also be likely to cause more damage to a mitre gate being closed as it was taking a load for which it was not designed. Both gates need to be shut before water is allowed to fill the lock, with the mitre supporting the gates as the lock fills. This was particularly so on the bottom gates of locks where subsidence was a problem, as at Wigan Top Lock. Although not so problematic on upper gates, there would still be the load created by stopping around 65 tons, if the boat was fully loaded with 50 tons.

There is a lot going on when strapping a boat, but generally it is reasonable on a narrow canal with single top gates, but less acceptable where there are mitre gates.

[IanM]

41 minutes ago, Pluto said:

That is a little simplistic. With a single gate, when a boat hits, all its force is on the top frame of the gate, so acting on the wood's weakest direction. With mitre gates, the forces are split, with some being in the same direction as with a single gate, but a significant amount goes into the lock side. Forces on the sill act in a similar fashion, only they are also fixed to the stonework or concrete of the sill.

I would suggest that strapping on a wide lock would not be effective as it would cause the boat to hit the lock side with greater force than if strapped from the lock side. Even then, this caused significant damage, still visible on many L&LC locks. The photo shows the wear on Wigan Top Lock from a lifetime being hit by loaded boats being strapped into the lock. Strapping on mitre gates would also be likely to cause more damage to a mitre gate being closed as it was taking a load for which it was not designed. Both gates need to be shut before water is allowed to fill the lock, with the mitre supporting the gates as the lock fills. This was particularly so on the bottom gates of locks where subsidence was a problem, as at Wigan Top Lock. Although not so problematic on upper gates, there would still be the load created by stopping around 65 tons, if the boat was fully loaded with 50 tons.

There is a lot going on when strapping a boat, but generally it is reasonable on a narrow canal with single top gates, but less acceptable where there are mitre gates.

 

 

 

I never said anything about a boat hitting a gate.

 

Yes, if a boat was to hit a pair of mitre gates at the point which they touched then some force would be directed back to the stonework along with the cill.  But even then that isn't straight forward. 

 

Bring in twisting and overturning of the gate(s) and things could get interesting.

 

I'll maybe model it in 3D and run some analysis on it if I find a spare hour or two.

 

I think though that we're basically agreed it isn't really the best idea.

[magpie patrick]

53 minutes ago, Pluto said:

That is a little simplistic. With a single gate, when a boat hits, all its force is on the top frame of the gate, so acting on the wood's weakest direction. With mitre gates, the forces are split, with some being in the same direction as with a single gate, but a significant amount goes into the lock side. Forces on the sill act in a similar fashion, only they are also fixed to the stonework or concrete of the sill.

 

 Whilst this is undoubtedly true, and we are drifting slightly from strapping to general abuse of gates, I do not know of an instance of single leaf gates "blowing" when hit, whereas I can think of several where this has happened with mitre gates on both wide and narrow locks. 

 

 

[Pluto]

Basically, I think we are agreed that its OK on a single gate narrow canal, but not suitable for mitre gates.