magpie patrick

But they're not braking the rationale for the rules Fibreglass boats are not allowed because the tunnel profile is tight - My then narrow boat Ripple came out of the tunnel with a deep scratch that would probably have been a tear a fibreglass cabin, but a canoe is nowhere near the maximum profile that will pass. Having been through on Ripple, I wouldn't take Juno (all GRP) through and I wouldn't have taken Lutine (GRP top) through, but I wouldn't worry in a canoe, other than whether I'd have the energy to paddle it through!

Going back to Bratch and the variants on the Monmouth Canal - Bratch locks seem to be about ten feet apart, they must be at least seven feet apart to allow the top gate to swing, the sets at Fourteen locks are rather further apart partly because they're wider and the gate is therefore bigger, but the proportions as a whole are more generous presumably because they were built with side pounds rather being modified staircases. Bratch were modified before the locks at fourteen locks were built - would the engineer in South Wales have been aware of the changes at the Bratch or was this a local development? How much did information transfer happen? I also note at least two other pairs near Cwmbran, one of which is now buried, where the canal doesn't widen out between the locks but the gap is quite a bit longer, probably around 40 feet.

I think it depends on what you mean by "navigation" but you could do worse than have a look at South Wales rivers, two things I've spotted. The Usk was navigated as far as Caerleon - there were wharves below the town bridge, it may have been navigated further. The river wasn't "made navigable" though. Before the Neath and Tennant Canals opened there was a lock cut on the Neath River at Aberdulais, it can still just about be seen on the east bank near (and under) the aqueduct. The Tawe was navigated at least as far as White Rock (east bank) and the copper works (west bank) - it is now impounded by the barrage and occasionally navigated as far as the Liberty Stadium - edited to add I see you've got this one

Mirriam-Webster dictionary Many commentators have objected to the comparison or modification (as by somewhat or very) of unique, often asserting that a thing is either unique or it is not. Objections are based chiefly on the assumption that unique has but a single absolute sense, an assumption contradicted by information readily available in a dictionary. Unique dates back to the 17th century but was little used until the end of the 18th when, according to the Oxford English Dictionary, it was reacquired from French. H. J. Todd entered it as a foreign word in his edition (1818) of Johnson's Dictionary, characterizing it as "affected and useless." Around the middle of the 19th century it ceased to be considered foreign and came into considerable popular use. With popular use came a broadening of application beyond the original two meanings (here numbered senses 1 and 2a - my note 1 below). In modern use both comparison and modification are widespread and standard but are confined to the extended senses 2b and 3 (my note 2 below) . When sense 1 or sense 2a is intended, unique is used without qualifying modifiers. Note 1 being the only one : SOLE being without a like or equal : UNEQUALED Note 2 distinctively characteristic : PECULIAR, UNUSUAL Foxton and Watford are unique, they are distinctively characteristic (note 2) of the Old Grand Union Canal and don't appear anywhere else. If you really want to be pedantic then you could claim I should have written the sentence in full "The side pound system of staircase locks at Foxton and Watford is unique to the Old Grand Union Canal" but that's a bit of a mouthful, and the rules of language do also allow us to simplify things so long as they are generally understood The Bratch system does appear on other canals (Stourbridge, Monmouthshire) so is not unique I didn't research that for the purposes of this, I just have an interest in how language evolves Right, I'd better go and do some work, otherwise my clients might get pedantic about deadlines (and me not sticking to them)

Not quite, if the side pond is full and the locks empty then, as you go down starting to fill the lower lock first creates room for more water - if you empty the lock above first the water runs to waster before you fill the second lock - repeat as you go down and you get a lot of water so in this position raising the red paddle first is beneficial BUT if the lock and the side pond are both brim full there is nowhere for the lockful of water from above to go, so it runs to weir - which is what is intended, but the system can't cope with every sidepond running to weir as you come down. In effect the sidepond level should alter depending on whether the lock it feeds is full or empty, and once a boat has been through all the locks are full or all the locks are empty - filling the entire system to the brim creates a situation that wouldn't arise if the system was left to manage itself

To get the side ponds full to the brim you also need to get all the locks full - which means that opening the red paddle has little effect. By the time you get to the bottom you've got ten lockfulls of water with you. In normal operation the only way the side ponds end up full is when the locks are empty.

There used to be a locky (in the days when they were paid - I think he was a stand in) who would carefully fill every side pound to the brim at the start of the day, there would fairly quickly be rather a lot of water at the bottom no matter how careful the boaters were.

I'm going to argue the point! That design is unique to the (original) Grand Union Canal - they have three staircases of a design that no-one else used. Going back to Bratch, these, along with the double at Stourbridge, are modifications of the original structure - this form was copied at 14 locks (4 doubles and a treble) on the Monmouth Canal (and acouple of other places on that canal( - the Monmouth Canal ones are not modified, they were built like that, yet the Glamorgan Canal, only a few miles away used conventional staircases. The difference was probably water supply - the Glamorgan had virtually unlimited amounts of the stuff. The (old) Grand Union design is better, but it is also later - they were built between 1810 and 1814, some 20 years after Fourteen Locks and around 30 years after the Bratch were modified IIRC (1780s or 90s) - Foxton and Watford also come from the other end of the telescope, the objective was to save money and the three staircases have 17 sets of gates and 6 pairs of wing walls between them when the equivalent single locks would have 28 of each. Whilst they wanted to save money they didn't want to waste water, and someone looked at Bratch, did what would now be called a value engineering exercise, and designed out the extra gate. Edited to add, if your really want a brain teaser look at the side ponds on the two rise at Bascote - they are as per normal single lock, and there are two per lock. It would have taken some coordination to get them used in the right order!

I have no idea BUT there are a few possibilities. First if the overhang was there in 1898 but not in 1901 its quite possible it was already (long) redundant in 1898. Second, and related, is that at one point navigation was up the Don before the cut was built, and some may well have continued for quite a while afterwards. When navigations changed route there were often wharves on the old route that still needed to be served. In addition there does seem to have been a Yorkshire habit of having wharves on weir streams... the Calder and Hebble had quite a few! Could someone who actually knows give an answer?

A boat that big on the Eastern end of the Trent and Mersey will be a pain to handle Although it was built for boats that big they weren't common on the canal even 250 years ago, and the channel isn't really up to a boat this size passing other boats. The length just complicates everything when you're already at the limit on beam - it's a lot of boat to get out of the way of someone else and if you're expecting others to get out of the way of you then you are going to irritate everyone you see, and also be disappointed when some don't. Also if these boats are intended for floaters rather than boaters they probably handle like a brick chicken shed. Trent and Yorkshire waterways like the Aire and Calder great (although be aware it's too long for Thorne Lock - so you're going round Trent Falls) - Trent and Mersey not so much.

What would you like to know? I studied the possible restoration of the entire route to Albion Mills - as far as Gorton reservoir it was relative easy, no obstructions, no services in the bed - after that it varies between messy and nigh on impossible, and there is much less left. That's isn't to say there is nothing left, but it is nowhere near a continuous whole. The railway crossing near Reddish has gone and there are houses on the line immediately south of that. I think there is still a bridge carrying a road over the canal at Broadstone Mill, and the line of the canal is clearly visible between Debdale Park (next to Gorton Reservoir) and the railway at Reddish, there is a sewer in the bed though which complicates things. I've sent you a PM

Indeed, although they predate Watford and Foxton by a couple of decades. Fourteen Locks on the Crumlin branch of the Monmouthshire Canal also work on the Bratch principle, as far as I'm aware Foxton and Watford are unique. Wrong type of side pond - the Bratch ones are between each lock, the type your thinking of are effectively part of the lock. Bratch (and Foxton) are really side POUNDS in that they serve the same function, in hydraulic terms, as a pound

If the tape measure was bendy it would over-measure rather than under measure. If you're going down the locks then presumably the boat went up them at some point?

Leisure boats have been using reverse as the normal way to stop in locks for at least sixty years - why is it becoming a problem now? More boats? Longer boats? More rubbish in the canal? To add - the "blown cills" that I've seen have often been caused by the failure of the structure around the seal, not the seal itself

In @IanM 's defence the bottom lock of that staircase (Bascote) wasn't empty - the top chamber had partially filled the bottom chamber but not by enough to get over the cill. I have filled a couple of staircase locks with the intermediate gates open, but you really do need to pay attention as the water pouring over the cill is quite impressive and will sink a boat in seconds. These days I'd probably open one paddle (and only one) at each end of the chamber. I've done the same thing going down with both locks full but one has to be really careful not to ground the boat in the top lock. What surprises me when I've done it is the water level barely drops in the lower chamber.

Just to clarify what I think has happened from the above and from the reference in Lindsay There was originally one lock, but the copings and top gates weren't high enough to cope with extreme events - so a new lock was added above the original. The copings and gates are higher but so is the bottom cill - it will be the same height as the upper cill on what is now the lower, open lock. For around 150 years these operated as a pair of locks, a flight of two, to give full depth over the top cill of the lower lock and the lower cill of the top lock. Once it became apparent deeper draught boats were a rarity the level between the locks was lowered and the gates on the bottom lock left open at both ends. This probably still gives around 7 feet over the cill (my educated guess - partly based on the history and partly based on the craft using the canal on a regular basis) If anything deeper comes along then the bottom gates of the lower lock will need to be closed and the length up to the upper lock filled until the boat can get over both cills. It would be the bottom gates due to the need to get over the top cill of the lower lock. If passage of deeper draught boats were a regular occurrence they wouldn't have done this - too much hassle filling the middle pound.

Splendid! FYI - about once a week this is my evening "television" watching (I only get to watch TV once or twice a week anyway) - your videos beat Bangers and Cash anytime

That makes sense, the only time I've visited was over forty years ago as a 14 year old, and i seem to recall that each lock had a roughly equal rise and fall then, but of course the canal was often used by fishing vessels then too. Edwards gives a minimum depth of water as 13 foot 6, so if the lower lock then had a lift of 6 feet there would now still be 7 foot 6 over the cill sailing straight through it. So the sequence would be - lower lock built as part of original canal. Then they found that this lock got overtopped regularly so built the upper one with higher copings, given the arrangement the fall of the two locks would even out over time, with the end of commercial traffic very few boats need more than 7 foot 6 inches so the gates of the lower lock can stay open both ends But on a much bigger scale! Noted, thank you

Attached is a photo off the web of Gairlochy Locks on the Caledonian Canal - on current plans we will spend a night nearby when we tour the Great Glen in August so I may get to have a wonder down. I'm curious - two inline locks (as in, one after the other rather than side by side) and in the picture the lower one has the gates open at both ends. The context is that the canal approaches Loch Lochy and there is a lock, presumably to lift the canal to the level of the loch, which may vary. The upper lock is not shallow and had a fair amount of spare wall. I can see a second lock might be needed along the lines of a flood lock to cope with an excessive variation, but surely that would be the upper of the two? I note, reading Lindsay's "Canals of Scotland" that they added a second lock sometime after the canal opened to reduce the risk of innundation, but I'm not sure how this arrangement achieves that. I guess the gates on the lower lock could be closed, and perhaps historically they were closed, but I can't see how it helps! Also, I don't know which one was added...