diamond locks

[Guest]

Just slightly off topic, for strange lock shapes try Castleford Lock on the Aire & Calder. It's bent. Watching the gravel barges go though is interesting, they have to turn in the lock.

Bob

It just so happens I have a video of Humber Pride (Not a gravel barge obviously) carrying out that very manoeuvre.

 

Castleford is also unusual in that there was once also another lock (behind where I am standing filming from in this video) that connected the cut to the river, hence it's rather unusual size/width, even for an A&CN lock.

 

[NickF]

 

Doesn't make any difference in the grand scheme of things. It isn't just one isolated lock!

That as I understand it is the whole point, It is such a small drop it has to be a large area to use a lot of water otherwise the pound below would gradually empty with each boat taking a big lockful out of the lower end of the pound and only putting a small lockful in at the top.

 

If three boats share the lock then you draw three lockfuls out of the lower pound and only put one in.

It just so happens I have a video of Humber Pride (Not a gravel barge obviously) carrying out that very manoeuvre.

 

Castleford is also unusual in that there was once also another lock (behind where I am standing filming from in this video) that connected the cut to the river, hence it's rather unusual size/width, even for an A&CN lock.

 

That is the only lock i have ever turned round in! (in a 57ft boat) I guess it couldn't be done in any other lock on the system. We went into the lock which then failed and none of the operating buttons worked, By the time CaRT arrived we didn't have enough time to go through so had to turn in the lock.

[bastion]

 

Doesn't make any difference in the grand scheme of things. It isn't just one isolated lock!

I understood it to be taking back the water that was lost from Nell Bridge lock to the river

[Scholar Gypsy]

 

That is the only lock i have ever turned round in! (in a 57ft boat) I guess it couldn't be done in any other lock on the system. We went into the lock which then failed and none of the operating buttons worked, By the time CaRT arrived we didn't have enough time to go through so had to turn in the lock.

 

West India Dock - see item about the virtual open day here. The lock, 955ft long overall, has a 450ft inner and 140ft outer chamber, is 80ft wide and 35ft deep [i think I have the right one...]. Some might argue this is not on "the system".

[magpie patrick]

I understood it to be taking back the water that was lost from Nell Bridge lock to the river

 

That makes sense - i'd only ever calculated the area/volume compared to the lock below each diamond lock, which makes Aynho somewhat inadequate, but it is about the same volume as Nell Bridge above it

 

It would be a reasonable deal with the owners of Mill rights that the canal could take as much out as they put in

[FadeToScarlet]

 

Going off topic for a second - How much of the waterways in that neck of the woods are as pretty as that? I had somehow imagined that area as pretty flat and featureless but it looks as if it could be worth considering as an area for a hire holiday.

Oh no, it's awful

 

 

Featureless, boring, not pretty at all

 

 

Definitely don't bother hiring...

 

[gazza]

Oh no, it's awful

 

 

Featureless, boring, not pretty at all

 

 

Definitely don't bother hiring...

 

You forgot to say it's flatter than a plate of piss with nothing but high banks as far as the eye can see.

 

Total waste of time.

 

 

 

 

 

 

 

 

Middle pic is my limit of navigation, good pub but a decent walk to get the paper! pretty as it is above there it doesn't do a lot for me.

 

St Neots makes more use of the river than the county town in my mind.

Just to the left out of shot in the bottom pic is the original Appleyard boat builders home to the great Harry Lincoln's operation. To the right and out of shot is the former A&L Babylon Site now Cathedral Marine, it always feels like our Elysian 27 is happy to come home.

Edited February 22, 2016 by gazza

[Scholar Gypsy]

You forgot to say it's flatter than a plate of piss with nothing but high banks as far as the eye can see.

 

Total waste of time.

 

 

 

 

 

Like this, indeed (December)

 

[gazza]

 

Like this, indeed (December)

 

that doesn't look much fun (the rowing I mean) much better view when the ladies are rowing that stretch in the summer.

[MoominPapa]

 

Middle pic is my limit of navigation, good pub but a decent walk to get the paper! pretty as it is above there it doesn't do a lot for me.

 

There's a pretty EA mooring in a backwater about half a mile up from there, which is worth a visit even if you go no further.

 

MP.

 

West India Dock - see item about the virtual open day here. The lock, 955ft long overall, has a 450ft inner and 140ft outer chamber, is 80ft wide and 35ft deep [i think I have the right one...]. Some might argue this is not on "the system".

You could do doughnuts in the Manchester Ship Canal locks, but they may similarly not count.

 

MP.

[Pluto]

It just so happens I have a video of Humber Pride (Not a gravel barge obviously) carrying out that very manoeuvre.

 

Castleford is also unusual in that there was once also another lock (behind where I am standing filming from in this video) that connected the cut to the river, hence it's rather unusual size/width, even for an A&CN lock.

 

Castleford is only a flood lock, with Bulholme the proper one for this section of canal. Below is an 1827 plan for improvements by Telford, showing the navigation at Castleford. The original Castleford Lock, from c1700, is not shown, but was on the north end of the mill weir. The flood lock which is shown dates from the 1770s improvements, with the additional basin to the east added later, probably around 1800. Telford's plan shows the new flood lock proposed in association with with the construction of the Knottingley & Goole Canal, which opened in 1828. The improvements also included the construction of Bulholme Lock. The remains of the lock from the 'new basin' into the river can still be seen today. Locks on the A&CN were extended again around the 1880s, in particular to accommodate the compartment boat traffic, and again from the 1960s..

[Dharl]

 

- these locks descend from the Cherwell, which breaks the hydrological continuity of the canal

 

If, for example, you have a canal with two deep locks, say ten foot drop, seperated by a shallow lock of say two feet, it doesn't matter. The highest lock will deposit a ten-foot lock volume of water into the canal below, the shallow lock will use two feet of it and eight feet of it will go round the bywash and into the canal below the shallow lock. You then empty the two foot lock, which tops up that which went round the bywash, and the next deep lock has enough water.

 

In this case though, the lock upstream empties into a river, and the water is lost to the river system, at these shallow locks the process starts again so the next lock down has only as much water as goes through the shallow lock, that's why is has been made wider. At Shipton the sums are bout right, but at Aynho the lock is stiill not big enough to carry enough water for the next lock downstream.

 

Although these locks are big, they can only take one 70 foot narrowboat. If three smaller boats share the shallow lock, all three will have to single out for the deep one, which will have to be operated three times, undoing the benefit of the extra volume of water carried by the diamond shape.

 

I think though the CRT have cut slots in the gates so there is always a flow through the locks now

 

thank you for a good post to clarify

[gazza]

There's a pretty EA mooring in a backwater about half a mile up from there, which is worth a visit even if you go no further.

 

MP.

You could do doughnuts in the Manchester Ship Canal locks, but they may similarly not count.

 

MP.

 

I am from Rushden, its about 14 miles to Bedford by road, My county town of Northampton has steadily got worse over the years so we found ourselves shopping more often in Bedford than Northampton, as towns go, Bedford is ok, I'm just not that keen on the stretch from Barford to Bedford.

 

We've stopped in Priory Marina a couple of times, it's ok for a visit to the Town as the Embankment is not really that boater friendly (apart from when the river festival is on) we've been up a fair way towards Kempston Mill but low levels meant we didn't get all the way.

 

Next time i'm taking my dinghy by car and throwing it in at Priory to svae the effort!

 

As you say, there are some lovely spots on the river to while the time away.

[Mike Todd]

Castleford is only a flood lock, with Bulholme the proper one for this section of canal. Below is an 1827 plan for improvements by Telford, showing the navigation at Castleford. The original Castleford Lock, from c1700, is not shown, but was on the north end of the mill weir. The flood lock which is shown dates from the 1770s improvements, with the additional basin to the east added later, probably around 1800. Telford's plan shows the new flood lock proposed in association with with the construction of the Knottingley & Goole Canal, which opened in 1828. The improvements also included the construction of Bulholme Lock. The remains of the lock from the 'new basin' into the river can still be seen today. Locks on the A&CN were extended again around the 1880s, in particular to accommodate the compartment boat traffic, and again from the 1960s..

Interesting to compare that map with the Google sat view. It looks as if the old line is now where there is now an unnamed road. However, at the point where that cut went under the road the names change - one side is Barnsdale Road the other is Lock Lane - both now A656. The pub still seems to be there (Griffin Inn) and also the road ENE of the road junction is labelled Navigation Road, also where the original cut was located.

 

The dock (Google says now Supreme Marine) looks as if it was part of the original cut.

 

On the other side of the main junction the oxbow lakes still show the original Calder river line before the proposed straightening. A third large Oxbow lake seems to be natural as it predates any straightening.

 

The area marked Pottery on the map now seems to be a fairly low grade assortment of industrial activities although the road is still called Pottery Street.

[blackrose]

I have to admit, while I enjoyed the novelty, the functional purpose of this diamond-shaped lock left me scratching my head.

 

What is/was the point exactly, or was it just done to do something different?

 

[magpie patrick]

I have to admit, while I enjoyed the novelty, the functional purpose of this diamond-shaped lock left me scratching my head.

 

What is/was the point exactly, or was it just done to do something different?

 

 

The current lock at Wyre has been heavily rebuilt without fundamentally altering the shape, a lot of locks on the avon were historically diamond, round or other variants simply because these were easier to build - straight walls had to be more precise and more stable, a diamond chamber could stand bulging or even a partial collapse and remain operational. It's a very ancient navigation. Being a river, water consumption didn't matter and i think some, or perhaps all of them were originally dry stone wall construction.

 

Elsewhere locks were turf sided with similar results

[blackrose]

Interesting. Thanks Patrick.

[Keeping Up]

Consider also the shape of the old "turf-sided" locks on the K&A. They were effectively diamond shape (to make them easier to build and maintain) but of course the sides tapered down to standard width at the base. The vertical piling keeps boats to the centre.