Canals will have to close - there's not enough replacement gates

[Captain Pegg]

17 minutes ago, magnetman said:

BW used Ekki for some works on the K&A about 20 years ago. I had some offcuts of this stuff. It doesn't float but burns well. 

 

Not sure how good it is for lock gates. I think maybe not ideal 

 

Observer article about BW's dutch timber supplier buying arms dealer hardwoods from Liberia. 

https://www.theguardian.com/world/2002/apr/14/uk.antonybarnett

 

It's an excellent marine timber. The problem - as others have said - is that it is very difficult to work.

[Momac]

Newark town lock gates are being replaced . Work in progress at the moment. Open days 26th and 27th Feb in case you fancy a walk along the bottom of the river .

[hughc]

In the early nineteen seventies the bottom gates at Dallow Lane were date stamped 1911 and they swung much more easily than their replacements.

[ditchcrawler]

22 minutes ago, hughc said:

In the early nineteen seventies the bottom gates at Dallow Lane were date stamped 1911 and they swung much more easily than their replacements.

That is because they had had over 70 years to bed in, the new ones will probably be OK in 2055

[Idle Days]

It seems that the manufacture of new gates is being delayed by the lack of suitable wood. 

[Tim Lewis]

52 minutes ago, Idle Days said:

It seems that the manufacture of new gates is being delayed by the lack of suitable wood. 

 

Where did you read this?

 

[MtB]

52 minutes ago, Idle Days said:

It seems that the manufacture of new gates is being delayed by the lack of suitable wood. 

 

 

A customer of mine bought an oak forest in Virginia a few years back, to get a continuous supply of oak for his hobby of building traditional oak barns. Maybe CRT would like his phone number...

[Pluto]

13 minutes ago, MtB said:

 

 

A customer of mine bought an oak forest in Virginia a few years back, to get a continuous supply of oak for his hobby of building traditional oak barns. Maybe CRT would like his phone number...

British/European oak is much better in damp conditions than American, which tends to split and distort more. One of the best books describing the variations in timber is George Sturt's The Wheelwrights Shop.

[magpie patrick]

There are issues with suitable timber which can shorten gate life - "English Oak" with accelerated growth doesn't last as well for example, and that's before the need to properly season the timber is considered. 

 

One big problem with both ekki and steel is they transmit far more force back into the lock wall in the event of impact from a boat. 

The Monmouth Canal is being fitted with "wood lookalike" gates made of steel, the locks will seldom be used until the canal is connected back to the B&A and given that the life of a gate is both time and use related, wooden gates would cost a fortune per use during their life - the steel gates are expected to last 120 years - wooden gates not used might not last 20 years. 

If I were specifying for a lock that would see a lot of use I'd specify oak, for a lock that would see less than (say) a hundred boats a year steel might be a better bet

[Idle Days]

32 minutes ago, Tim Lewis said:

 

Where did you read this?

 

Didn't read it, heard it regarding Watford lock repairs and gate replacement. One set due for replacement has reportedly been postponed for that reason. Given the import mess created by Brexit it seems quite likely that timber imports are also being delayed along with the tinned tomatoes.

[Captain Pegg]

5 minutes ago, Idle Days said:

Didn't read it, heard it regarding Watford lock repairs and gate replacement. One set due for replacement has reportedly been postponed for that reason. Given the import mess created by Brexit it seems quite likely that timber imports are also being delayed along with the tinned tomatoes.

 

I have heard non-compliance (or perhaps unwillingness to meet) with FSC certification requirements and civil unrest in Cameroon cited as reasons for problems with supply of certain hardwoods in a non-canal environment in recent years so that doesn't surprise me, even without the added complexities of importing things in recent times.

[Rob-M]

I was told Last week that all the lock gates are made from oak sourced in the UK, not imported.

[Idle Days]

40 minutes ago, Rob-M said:

I was told Last week that all the lock gates are made from oak sourced in the UK, not imported.

 

In that case they may be waiting for them to finish growing.

[Captain Pegg]

1 hour ago, Rob-M said:

I was told Last week that all the lock gates are made from oak sourced in the UK, not imported.

 

Always useful to have facts, although they do get in the way of many a good story.

[David Schweizer]

4 hours ago, Rob-M said:

I was told Last week that all the lock gates are made from oak sourced in the UK, not imported.

 

 It would be helpful if you could reveal the source of all the information you have posted.

[Momac]

On 11/02/2022 at 13:42, IanD said:

They're durable but are sometimes badly balanced (because steel doesn't float) and can be very heavy to open and close. There's no perfect solution to the gate problem... 😞

Steel has a density of 7850kg/m3 compared to Oak at a density of 720kg/m3. A factor of about 10

The oak will be closer to the density of water when saturated.

 

However steel has a bending strength of about 275/Nmm2 compared to Oak at 10N/mm2. A factor of 27

And youngs modulus for steel is 210,000N/mm2 and Oak about 10,000N/mm2 a factor of 21

 

So steel is  20 odd times stronger and 20  times stiffer than Oak for the same dimensional properties.

So in simple terms 20 odd times more Oak  is required compared to steel.

 

Therefore , since steel is only 10 times more dense than Oak but is 20 times stiffer and 20 times stronger , there is potential for steel gates to be lighter than Oak gates.

 

The weight of timber gates will be substantially offset by buoyancy only for the upper pair of gates in a lock since the lower pair of gates see little or no buoyancy when the gates are being swung.

 

 

[Rob-M]

1 hour ago, David Schweizer said:

 

 It would be helpful if you could reveal the source of all the information you have posted.

I visited the open day at Grindley Brook staircase and asked the CRT person doing the tour where the wood for the gates was sourced.  As the staircase has a set of steel gates we also had a discussion on steel gates Vs wooden gates and he said the preference was for wooden gates.

[magpie patrick]

30 minutes ago, MartynG said:

The weight of timber gates will be substantially offset by buoyancy only for the upper pair of gates in a lock since the lower pair of gates see little or no buoyancy when the gates are being swung.

 

 

 

That's not really true as on most locks anywhere between a third and a half the gate is submerged even for the bottom gates. Even at Marple (lock depths just over thirteen feet) a quarter of the gate is submerged. 

[Mike Todd]

21 minutes ago, magpie patrick said:

 

That's not really true as on most locks anywhere between a third and a half the gate is submerged even for the bottom gates. Even at Marple (lock depths just over thirteen feet) a quarter of the gate is submerged. 

The critical word on the quote you criticise is 'substantially'.

 

Given that (using figures given earlier) oak is only 30% lighter and if 25% is submerged then only 7%.

 

That assumes that wooden and steel gates are same volume but steel ones are actually much less volume. I don't know by how much - although most steel gates have some wood elements.

[Momac]

22 minutes ago, magpie patrick said:

 

That's not really true as on most locks anywhere between a third and a half the gate is submerged even for the bottom gates. Even at Marple (lock depths just over thirteen feet) a quarter of the gate is submerged. 

Okay  - depends on the depth of the lock 

It's been a while since I  did  little canal locks.

On the Trent the gates are powered  of course but even so they are timber . To me they are normal locks form a dimensional point of view but really they are exceptional compared to most on the canals.

 

 

[Richard Fairhurst]

On 13/02/2022 at 10:09, Rob-M said:

I was told Last week that all the lock gates are made from oak sourced in the UK, not imported.

 

Yes, that's my understanding too. Often from Pontrilas in the Welsh borders, I believe.