Flash lock water flows

[Pluto]

I have been researching flash locks recently, and came across this from a German publication called Forum IFL, vol 15, in an article about the Dükerschleuse on the Stecknitz Navigation. The upper graphs show the calculated water depth and speed if the gate was opened at 6-00 and closed at 14-00, with the lower graph shows the variation in water depth immediately downstream of the gate and at locations further downstream. In actual operation, the lock was used once or twice a week, and a fleet of a dozen or more boats would pass on one opening. The lock survives as an ancient monument, and was by-passed after the construction of the Elbe-Lübeck-Canal with its Hotopp locks operated by air pressure created by the fall of the lock.

[Heartland]

It must be a matter of the flow of water and the depth of fall. The flash lock was an early form of assistance for getting rivercraft up and down steam. These German documents may be of use to understand some basic facts, such as the depth of fall.

 

If a flash lock is opened then water above the lock would be lowered no doubt and maybe the levels on either side come close to be the same if the lock was opened for such a lengthy period. Also, when would it be expedient for craft to travel upstream?

 

[John Brightley]

1 hour ago, Heartland said:

Also, when would it be expedient for craft to travel upstream?

As I understand it, craft travelling upstream would pass through the flash lock after the boats going downstream. There is an account in " To Maintain and Improve - The History of the Lower Avon Navigation Trust" (DH Burlingham, 2000) of the use of Pershore Watergate (which I believe was the UK's last flash lock to be used) in 1953, which says that boats arrived before 8pm. The gate was winched closed, the paddles closed and by 9am the next morning the river had risen enough for boats to proceed.

The book also includes photos of the barge Pisgah going up through the gate in 1955.

[Pluto]

Opening a gate seems to have made navigating that gate possible for around 2 hours, but the gate was kept open much longer as the flow, although much reduced, still had an effect on levels further down stream, ensuring that it was possible for boats to work both up and down stream more easily. 

 

By understanding the various types of flash lock on the continent, and their development, a case can be made for their proposed use on Brindley's earliest proposals for 6 feet wide narrow canals. Roads would have crossed these canal using fords, where the depth of water was to be around 2 feet, and I can see a flash of water would be of use in helping boats over such shallows.