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Flash Locks - how did they work in practice?


Tam & Di

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I read somewhere, possibly on this forum, about portable staunch kits that boatmen could carry with them and stretch across the river as a temporary flash lock to build up water levels so they could progress, upstream as well as downstream.  Now I cant find it!  Any suggestions please?

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I would consider that very unlikely, given the forces involved in holding back water. I have heard of by-wash weirs being raised by boatmen  to increase depth on a canal, but that only needed a suitable plank of perhaps ten feet in length. I am currently translating some German descriptions of flash locks from around 1800, the best modern work on the subject being the paper on the Stecknitz locks by Kai Wellbrock in 'Hamburg - die Elbe und das Wasser', ed. Christoph Ohlig and published in 2009. There are also interesting French descriptions, particularly in de la Lande's 'Des canaux de navigation et spécialement du Canal de Languedoc' from 1778 and, of course, Belidor's Architecture Hydraulique.

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Found the reference now-- H. McKnight Shell Book of Inland Waterways 1975 p34  quoted in Sean Odell's The Essex and Suffolk Stour A History p45

"Fen lighters were known to be using their own portable 'staunching tackle' until well into the 19th century in order to safely navigate certain stretches of the River Nene.. The system, said to have been originally developed by the Romans..on the River Lee and other inland waterways, consisted of a kit of posts, an empty boat and a canvas sheet. A temporary weir would be constructed to sufficiently raise water levels to aid navigation"

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15 hours ago, Jeremy Lander said:

Found the reference now-- H. McKnight Shell Book of Inland Waterways 1975 p34  quoted in Sean Odell's The Essex and Suffolk Stour A History p45

"Fen lighters were known to be using their own portable 'staunching tackle' until well into the 19th century in order to safely navigate certain stretches of the River Nene.. The system, said to have been originally developed by the Romans..on the River Lee and other inland waterways, consisted of a kit of posts, an empty boat and a canvas sheet. A temporary weir would be constructed to sufficiently raise water levels to aid navigation"

The best source of information is probably 'Flashlocks on English Waterways' by Lewis, Slatcher and Jervis, published in Industrial Archaeology in 1968, with an addendum in 1971. "Canals of Eastern England' also offers some description of Fenland waterways and their staunches and flashlocks. As to portable tackle, I would expect most Fenland boats to carry some materials for stopping staunches from leaking, given the poor state those waterways were in by the start of the 20th century. A piece  of canvas, positioned by posts, would certainly be an effective way of reducing leakage through a narrow staunch, but suspect it would not be so simple to make a temporary weir. Even where the change in level was one foot, the water pressure would require something pretty substantial. There were numerous ways of creating staunches, weirs and flashlocks, and it would be useful to know to which your description relates.

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FWIW, back in the late 60s I did hear of a boater who wanted to exercise their right to boat to the head of the Thames navigation in a motor launch (Cricklade I think, not the end of navigation as defined by the TC and then EA). Anyway they hit shallows and alleged they drove a herd of cows into the water to impede the flow and raise the level. If this is true I could well imagine the boatmen of old doing similar.

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Any idea where I can obtain copy or extract of 'Flashlocks on English Waterways' by Lewis, Slatcher and Jervis, published in Industrial Archaeology?

Thanks!

This has some good stuff https://vdoc.pub/download/waterways-and-canal-building-in-medieval-england-6pcbfeliqsr0

Including the massive economic benefits of water transport when roads were practically non existent. You would go to great lengths to make a river navigable before resorting to road transport.

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You can try abebooks for Industrial Archaeology vol.6, No.3. There is one for sale at the moment. The attached is a rough translation I did in 2013 of an article by Martin Echoldt, who was one of Germany's best-known waterway historians. There is also 'Du Pertuis…a l'Ecluse' by Charles Berg and published by the Association des Amis du Musée de la Batellerie, No.37, 1997. Although in French, it is in cartoon format, so a bit easier to understand. The medieval waterway book is good, but I am always a little wary of medieval historians as they can base their ideas on very little definite information. History is all about interpretation, but there is definitely more to go on for more recent history. The major problem with flash locks is that there are so many different types, and there is very little to differentiate what is being described in English, whereas French and German have more specific terminology, probably because they had good technical education many decades before we did. My last book does look at this, as well as being a translation of a useful Austrian book on canal engineering, written by someone who had visited England in 1795 and returned to Vienna to build an English narrow canal.

2013 Eckholdt, The development of the lock chamber.docx

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This has some good stuff https://vdoc.pub/download/waterways-and-canal-building-in-medieval-england-6pcbfeliqsr0

Including the massive economic benefits of water transport when roads were practically non existent. You would go to great lengths to make a river navigable before resorting to road transport.

Thanks!

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1 hour ago, Pluto said:

You can try abebooks for Industrial Archaeology vol.6, No.3. There is one for sale at the moment. The attached is a rough translation I did in 2013 of an article by Martin Echoldt, who was one of Germany's best-known waterway historians. There is also 'Du Pertuis…a l'Ecluse' by Charles Berg and published by the Association des Amis du Musée de la Batellerie, No.37, 1997. Although in French, it is in cartoon format, so a bit easier to understand. The medieval waterway book is good, but I am always a little wary of medieval historians as they can base their ideas on very little definite information. History is all about interpretation, but there is definitely more to go on for more recent history. The major problem with flash locks is that there are so many different types, and there is very little to differentiate what is being described in English, whereas French and German have more specific terminology, probably because they had good technical education many decades before we did. My last book does look at this, as well as being a translation of a useful Austrian book on canal engineering, written by someone who had visited England in 1795 and returned to Vienna to build an English narrow canal.

2013 Eckholdt, The development of the lock chamber.docx 193.48 kB · 2 downloads

Many thanks!

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On 20/07/2022 at 17:06, Jeremy Lander said:

Fen lighters were known to be using their own portable 'staunching tackle' until well into the 19th century in order to safely navigate certain stretches of the River Nene.. The system, said to have been originally developed by the Romans..on the River Lee and other inland waterways, consisted of a kit of posts, an empty boat and a canvas sheet. A temporary weir would be constructed to sufficiently raise water levels to aid navigation"

 

Which interestingly is a reasonable description of a Portadam, although they use angled metal frames and PVC sheeting rather than wooden posts and canvas.  As seen near many waterway repairs.

 

14 hours ago, Pluto said:

Even where the change in level was one foot, the water pressure would require something pretty substantial.

 

Yes and no.  The head pressure of a foot of water is one foot of water, no matter how far upstream it extends.

 

I've had this discussion with people who won't believe stop planks will work on Blackburn top lock because there's 23 miles of water behind them.

 

They do work though...

 

 

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9 hours ago, TheBiscuits said:

 

Which interestingly is a reasonable description of a Portadam, although they use angled metal frames and PVC sheeting rather than wooden posts and canvas.  As seen near many waterway repairs.

 

 

Yes and no.  The head pressure of a foot of water is one foot of water, no matter how far upstream it extends.

 

I've had this discussion with people who won't believe stop planks will work on Blackburn top lock because there's 23 miles of water behind them.

 

They do work though...

 

 

 

Absolutely. It's the depth or 'head' of water that creates the 'pressure', not the length or width.

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9 hours ago, TheBiscuits said:

 

Which interestingly is a reasonable description of a Portadam, although they use angled metal frames and PVC sheeting rather than wooden posts and canvas.  As seen near many waterway repairs.

 

 

Yes and no.  The head pressure of a foot of water is one foot of water, no matter how far upstream it extends.

 

I've had this discussion with people who won't believe stop planks will work on Blackburn top lock because there's 23 miles of water behind them.

 

They do work though...

 

 

Modern portable dams are effective, the question is whether something similar 100 years ago would be light enough to carry around, and how many men would be required to install one. And the answer to my post is just yes, as I only stated that the load was relative to the fall, not to the volume of water behind.

 

To get some idea of what is being dealt with, this is a flash lock near to the Canal du Nivernais which was used for floating timber. The fall is probably the maximum which can be dealt with by a flash lock.

1995 Canal de Nivernais 351.jpg

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5 hours ago, Derek R. said:

 

Absolutely. It's the depth or 'head' of water that creates the 'pressure', not the length or width.

True.  But the width of water is a factor in the force against the planks; not so the length.

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3 hours ago, Tacet said:

True.  But the width of water is a factor in the force against the planks; not so the length.

On reflection that is correct. Holding back a seven inch wide section of water would be far easier than a seven foot section.

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14 hours ago, Jeremy Lander said:

Just need more posts I guess. I wouldn't be surprised if the Portadam system (worth a Google) is not far from what they did centuries ago. Just wood instead of aluminium and canvas instead of polythene. 

There are two problems. The first is how to get a good foundation, with excavators of some sort usually being used today. Dredging to get a solid base would have been difficult prior to their introduction. The other problem is how to stop wooden frameworks from floating away. Modern metal frames make this less likely.

 

It would seem to me, having read quite a lot on the subject, that there are two types of flash lock; those built to avoid mills with undershot waterwheels, and those to avoid mills with breastshot wheels. The former are much older, and would require a fall of about one foot, with a weir to match. Breastshot wheels were introduced in the 18th century, and can require a fall of three feet, and I have certainly found cases where there were three mills, and this was reduced down to one in the late 18th century, almost certainly because the more efficient breastshot wheel was being used. With the older type of wheel, it may be possible to create a temporary weir, but it would be much more difficult with breastshot. Weirs in the fenlands may have tended to serve the former, though it would be interesting to survey the type of mill and wheel found on the smaller fenland rivers.

 

The photo shows a mill site on the Onega River, near Kargopol in northern Russia. The wheel was in the wooden frame in the foreground, while the 'weir' hardly disturbs the water flow in the background.

P6198943.jpg

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Thanks for this. Pretty sure Portadam don't use excavators. Sheeting lays on river bed I think. The slope of the posts also helps. I don't think staunch had to be anything like watertight as it was just about temporarily raising level by a foot or two. Really want to give it a try! 

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This is no river in flow, so will not be directly comparable, though it does use sheeting in combination with a latticework of triangulated poles to support the sheeting.

North Circular Road Aquaduct replacement in 1992. (Note the WWII Pill box).

 

98612072_NCircularBWimg046(2).jpg.c2a67271a22f663147c2eaaf508d8672.jpg

 

928669084_NCircularBWimg046(4).jpg.22dd776b9e4354469fb4c732e82be862.jpg

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Re Portadams, the photos on their website show excavators nearby.

 

On the North Circular photo, the supports are scaffolding, so something which will not float, which makes the result easier to achieve.

 

Below is how they used to do temporary repairs on the L&LC, with wooden piles and wooden tongues between each pair of pules to stop leakage. From figures I have found, they used more wood annually for this type of repair than they did for building new lock gates. There was a simple hand-powered driver frame for inserting the piles. Of course H&S does not allow this type of piling today, though I have found no records of any accidents.

bank repairs.jpg

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Great thanks! Really useful images. For purposes of my research (12th century stone transport) the rivers in question would be slow moving and fairly narrow, e.g. the Welland and the Essex Blackwater, so an arrangement like this would be entirely feasible. Maybe the posts were driven into river bed at an angle, or they had ready made frames, possibly weighted down with stones. The canvas would quickly stabilise them. It had to be easily removable so they could take it on to the next stretch. 

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The first question you need to ask is, How much would a suitable length of canvas-type cloth cost? Would local boatmen be able to afford it? It is always easy to overthink what would be used. In Russia, they continued to use Voloks as part of their navigation system into the 20th century. These were shallow sections of streams along which boats could be dragged. The harsh Russian winters meant that transport by water was only available for half the year, and any structures were likely to be damaged by the frost. The photo shows me being transported along such a river/stream serving Lake Kenozerski, near Kargopol, in northern Russia. I have a copy of a Russian book on walking old waterways, and there seems to have been a large number of such transport routes. Northern Russia is comparatively flat, with the sources of rivers flowing in opposite directions very close to each other, making voloks possible.

 

Having looked at the history of inland waterways across Europe, the size of boat using rivers and streams without major navigation structures were large enough for carrying building stone in very shallow waters. The second photo shows models of boats associated with rivers in the Rhine catchment on display in the Mainz Early Shipping Museum, which I can recommend. They have several survivors from the Roman period. When it comes to river transport, the one thing I am continually having to explain to non-technical historians is how easy it is to move things on water. Boats or rafts used for carrying materials were often just used for one journey, being broken up for their timber at the end of a journey. Because today we have so much access to information, it is all too easy to overthink the solution to a perceived problem.

Lake Kenozerski, near Kargopol, voloki?.jpg

DSC_0075.jpg

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