magnetman

I'm surprised they are happy with the drones. To be fair they seem to be out of the way of the operational staff. Drone accidents are not unknown. I wonder if the other vessel is going to be done at night. A nice lighting tower is ready to be used about now.

Yes. And if it performing a structural role you definitely don't use the thin stuff. Different story on a level canal but up in the air it is obviously not a good plan. Apart from anything else it adds weight to the top. If those piles were 30ft long the collapse would have been almost impossible. I wonder who is in there Or is that the other end of the 'piping' tunnel. Burrowing animal. "always wanted to live there thank god the water has finally gone away this is where the family lived all those years ago"

Not all piling is created equal.

30ft Larssen piles. The real deal. Often 12mm thick which is going to give it a very long useful life. These cadmiun or zinc plated Mickey mouse piles are 6mm thick if that and clearly not long enough. The type of thing which cowboy contractors sell to riverside house owners and bang in at the end of their gardens. This Mickey mouse rubbish has low structural strength and as is obvious from the pictures it just creates a weakness at the edge of the bank if fitted on an embankment. You can't hammer 8ft consumer grade thin wall piling into a major embankment it's just not appropriate. Unless the priority is to create a short term high public awareness walkable path.

If they are proper long thick type like Larssen piles that is probably alright. These ones are short and thin. So the rust out and also are not long enough to be structurally supportive. They are not at all long as can be seen from the pictures of the sheets on top of the narrowboat. Mickey mouse and I think @Gybe Ho had made a good observation such is that the primary reason for them being installed was for the footpath not the canal integrity. You can see from the size of the narrowboat that these things short sheet piles are rubbish.

The plain green and red Buckby can is nice.

I think it's the other way round where you need to worry.

My Ai said " Your merciful and most gracious Lordship, piping is essentially the "silent killer" of embankments. It is a form of internal erosion that creates a hollow tunnel—a pipe—right through the heart of the structure. If left unchecked, it can lead to a sudden and catastrophic "blowout." The process is particularly "sneaky" because it often starts at the back and works its way forward. Here is how it unfolds: The Stages of Piping Initiation (The Leak): Water begins to seep through a weak point in the bank, such as a small crack, a decaying tree root, or a gap next to a drainage pipe. Backward Erosion: As the water exits the downstream side (the "toe"), it carries away tiny grains of soil. Because those grains are gone, the water flows faster, pulling more soil out. The hole begins to grow backwards into the embankment, toward the water source. Progression (The Tunnel): The small hole turns into a continuous pipe or tunnel. At this stage, you might see "muddy water" exiting the bank, which is a sign that the internal structure is being hollowed out. Breach (The Collapse): Once the pipe reaches the water source (like a river or reservoir), the flow becomes a torrent. The "roof" of the pipe collapses, the embankment "gives way," and you have a full-scale breach. ---- The reference to this working "backwards" is particularly eye opening. The leak going out of the towpath side is burrowing back across and under the canal bed. I think it is hard to argue that this didn't happen. This would punt to the hole marked with the fence as being the cause of the failure. Good question. I still think putting great big blades into embankments is something canal engineers would dislike. Yes maybe 30ft Larssen piles with 12mm wall thickness but these are thin short campshed piles. A false friend.

The fact it opened up on the other side may be incidental to smaller failure or hollowing out on the inside. It would be very unlikely for it to collapse outwards on the inside of the bend even if that was the origin of the structural failure. If you have a curved stick it's much easier to break it so that it fails on the outside of the bend than the inside. Once the failure has begun and water is moving in order to obey the laws of gravity it could be the pressure caused by the rapid arrival of that water which then blows the outside of the bend open. In this scenario it would have started as a hole on the inside of the bend. The water wants to go there then the hole is blocked suddenly resulting a tidal wave effect. The inside of the bend can't break because it is structurally stronger than the outside so this wave effect blows the outside open. The lift bridge is narrow so if there was a lot of water coming from the other direction to escape into a hole which then blocked up the level would rise. Like if you open the paddles to empty the lock then shut them suddenly. The water is already on its way out of the apertures and thinks that is where it is going. When you close them the water doesn't just stop moving and remain calm. It's still got a lot of energy.

It seems very improbable that the little wooden fence just happened to be put exactly where the earth split open. Maybe that crack there is where the water flowing through the piling was going, creating it's own little tunnel under the path. (Still from yt video) It does ask the question about what do you do if water is known to be flowing through bank protection on an embanked section. That is a significantly more serious position that water flowing through the piling on a non elevated section. In the latter case nothing bad will ever happen other than the path being more dangerous but on an embankment ( with the generous addition of hindsight ) it can't just be left like that. This could be seen as allowing a hazard or 'trap' to develop. Not the hole in the path but the stability of the elevated structure. If this had happened in the daytime with people walking around in the area or on paddle boards it could have been quite a serious incident. Could have been quite a lot of fun for a whitewater canoeist. I know Tony Dunkley has been banned because he is far too abrasive and anti the CRT but I think some older members know he is a fairly knowledgeable old geyser. So here is his solution, which did make me titter a little. "There are various suitable means for temporarily stopping or reducing such leaks readily available to the C&RT. One quick simple method would have been to stuff Ms. Sharman and her former boss, Parry, into the hole at the canal bank edge and pack them round with a few barrow loads of clay, . . "

Is ARCTURUS still about? Used to be at Ivinghoe on the offside there but did look quite rough. I have not been past there since 2010.

Yes. That cottage is a survivor which is good.

There were local reports suggesting water was flowing through the piling into the void. If that is true then where was this water going? Maybe just rumours. It does look a bit like a hole. Water has a habit of finding holes and gravity has a habit of making water go downwards.

I've heard of kettles which recess into the hole on the top of a range when one removes the round disc but never knew if they were real or theoretical. It looks like they are real then. Could be from any stove not just a Boat.

I have a sneaky suspicion they might have been thinking about cutting costs and doing it on the towpath. Widebeans are quite large objects and there would be two transport costs as well as the space needed to do the work. If one could just chuck it in the canal the overheads magically disappear. It would also be fairly easy to house the fitters aboard during works thus saving some transport costs.

It's a bit of a worry if the CRT have to pay for providing water to householders' taps. These privatised water companies have got their business well sorted !

I didn't say that. One could come to a conclusion that if there a hole in the towpath on an embankment with culverts under it that it may be wise to put in a prohibition on mooring. It's not about the exact date it is about identifying a hazard. Water leaving a canal is not a problem in most situations. An embankment failure is a significant problem if there is something on top of it at the time. Surely there would be target type risk assessment like they do with trees. Probability of someone being there when it falls.

I think they probably could have predicted it given that there was a hole in the towpath big enough to warrant a wooden fence around it. That was not a burrowing animal.

The biggest loser is the canal itself. Unless the CRT can do some sort of fund raising thing based on how they heroically saved the Boats. In reality it's more likely that everyone will forget about it and the contractor will go away with a great big wad of cash. Which to be fair is the only reason they exist. (In my previous post 'nothing wise' was supposed to say 'nothing else')

Do insurance companies operate like that? If a Boat was insured for £30k but ended up in a position where it needed £15k repairs and cost £20k to recover or £5k to cut up what would the insurance company do? Do they get involved with great memories or do the loss adjusters just work out the most effective solution? Of course there is the possibility that the owners are paying the contractors.

It will be interesting to see how much value the contractors place on these two narrowboats. At the end of the day/week once they are out and taken away the total cost of the exercise divided by two will be the perceived value of each vessel. Otherwise they could have just paid the owners that minus cost of cutting and removing. Nothing wise will have been achieved. I also wonder about the wisdom of using machinery on a canal embankment which had recently partly collapsed. The cost of rebuilding this embankment is going to be many times more than any second hand narrowboat would ever be worth even in mint condition. Who is paying the contractors and how much are they taking.

Another possibility here is that another Boat (lots of Boats around in the urban environment n the picture) discharged a lot of dirty bilge oil and some of it has simply hit and stuck to the side of the OP Boat. No sign of recent dribbles. The black mark to the left looks too me like oil not water. If you look carefully at the original pictures there are at least three other vessels in close proximity and a multi storey block of flats. Wet weather. Being double moored. Vessel alongside has auto bilge pump and cruiser stern.. Splat. This also explains the oil 'on the floor'. It is someone else's bilge. And that black mark on the side is oil.

Cor that could get expensive. Contractors would be all over that like a rash.

I did idly wonder why the choice was not made to condemn and cut up but it seems that this would not be acceptable and the CRT would get very bad press from it. It could have been done very quickly. Owners allowed in to retrieve personal effects then break into parts and remove. I live on a Boat with nowhere else to go so I don't particularly cherish the thought but in terms of efficiency and cost plus risk of further damage to the canal embankment... It would be interesting to know what the total bill is for the contractors. Presumably this will be a publicly available figure. And who actually is paying out via an insurance policy, if anyone? Is it the CRT for having a failure which they potentially knew was coming (the fenced off section is a bit of a giveaway) or the owners wreck / stranding insurance? As a hypothetical worst case scenario let's say a weld has split somewhere due to the tumbling and the Boat won't float once it has been hauled out of the hole. What then? You have shelled out for a high visibility contractor but you still can't actually get the steel box out of the area if it won't float. Obviously it's a bit unlikely and they are very durable.