The marina I'm currently staying in doesn't have stop planks on site, they have a contractor 8 miles away who will come and deploy some in the event of an emergency. The section of canal outside has an 15ft embankment opposite the entrance.

Despite the chances of an embankment breach being extremely unlikely, the risks are minimal but the consequences would be severe, especially for the 100 or so liveaboards in there.

Is this the case at some of the other marinas? All others I've stayed in have their own stop planks. It seems a barmy arrangement to me.

A stack of stop planks left out exposed to the weather and never used for years. What sort of condition do you think they would be in if they were ever needed to be used? And that's assuming there are folk about at the relevant time who are able to deploy them.

1 hour ago, Grassman said:

but the consequences would be severe, especially for the 100 or so liveaboards in there.

100 boats sitting on the bottom of the marina. A nuisance, yes. Severe? Not really.

7 minutes ago, David Mack said:

A stack of stop planks left out exposed to the weather and never used for years. What sort of condition do you think they would be in if they were ever needed to be used? And that's assuming there are folk about at the relevant time who are able to deploy them.

100 boats sitting on the bottom of the marina. A nuisance, yes. Severe? Not really.

Sums up my thoughts too.

And re the stop planks, even if they weren't rotten I bet the water level would be at least a couple of feet down by the time a breach has been noticed and team has been raised and arranged to get there and put them all in.

I suspect stop planks at marina entrances are more to do with leak detection and water loss prevention from the network if the marina itself leaks, than to do with protection from water loss during embankment breaches.

Depends on quite a few factors. Are there any houses or anything else at the bottom of that embankment? How long is the pound outside the marina entrance? If it's a relatively short pound would stopping the marina entrance significantly reduce the volume of water flowing through a breach?

All of this will have (or should have) been looked at by the EA who are the flood risk authority in close liaison with CRT. They inspect all marinas every few years I understand.

14 minutes ago, David Mack said:

100 boats sitting on the bottom of the marina. A nuisance, yes. Severe? Not really.

Unless of course the marina is an ex gravel pit and more than 4ft deep in which case, unless there are floating pontoons, the boats would be hanging on their ropes.

1 hour ago, Grassman said:

The marina I'm currently staying in doesn't have stop planks on site, they have a contractor 8 miles away who will come and deploy some in the event of an emergency. The section of canal outside has an 15ft embankment opposite the entrance.

Despite the chances of an embankment breach being extremely unlikely, the risks are minimal but the consequences would be severe, especially for the 100 or so liveaboards in there.

Is this the case at some of the other marinas? All others I've stayed in have their own stop planks. It seems a barmy arrangement to me.

I had a mooring in a short lock pound. When the gates on the low side were at the end of their life, levels could easily drop a foot overnight. You learnt mooring line arrangements to cope with it and to avoid getting trapped under a jetty as the levels came up again. If the embankment breaches, your boat will end up on the bed. Find a way to moor that it will cope, or have a sharp knife to hand to cut yours and others mooring ropes, if they go taut.

Is your boat on a fixed jetty, or floating pontoons?

47 minutes ago, GUMPY said:

Unless of course the marina is an ex gravel pit and more than 4ft deep in which case, unless there are floating pontoons, the boats would be hanging on their ropes.

If the adjacent canal is only 4 feet deep, then unless the breach washes out the entire entrance structure, including the stop plank cill, the water level will only drop by about 5 feet and the boats will stay afloat (but might still hang up on their ropes).

Thanks for your feedback boys and girls.

In answer to the points raised.

The pound is about 8 miles long.

There is no adjacent housing below or near to the embankment, just open fields.

100 boats with liveaboards would be severe, especially for the quite a few people with disabilities. The depths vary but under our boat it's about 5 ft and my partner is disabled.

I appreciate that stop planks warp, rot, weather etc especially if left uncovered, I still would like the marina to have them on site, properly protected from the elements, tested periodically say every 6-12 months, and replaced or altered if necessary. It would also give the staff and nearby liveaboards some practice deploying them, a bit like a fire drill.

Yes maybe I'm paranoid but for the extortionate mooring fees they're charging it's the least they could/should do 🙂

Testing stop planks is bloody difficult. They can really only be easily sealed when there is good flow through them to draw ashes in to the gaps. That means a fair difference of level either side of the planks. Easy to achieve if you are at the head of a lock, rather harder if you are trying to stank a marina off from even a half-mile pound.

In the standard CRT/BW double stop log you can do it with pumps, but they need to be surprisingly large. A single 4 in pump doesn't cut it. You then run into the problem of getting the kit to the plank grooves. Four and six in pumps are heavy!

It can be done. Allow at least four hours to get a good seal. Been there, still have the T-shirt earned at Circus Field. Twice.

1 hour ago, Grassman said:

Thanks for your feedback boys and girls.

In answer to the points raised.

The pound is about 8 miles long.

There is no adjacent housing below or near to the embankment, just open fields.

100 boats with liveaboards would be severe, especially for the quite a few people with disabilities. The depths vary but under our boat it's about 5 ft and my partner is disabled.

I appreciate that stop planks warp, rot, weather etc especially if left uncovered, I still would like the marina to have them on site, properly protected from the elements, tested periodically say every 6-12 months, and replaced or altered if necessary. It would also give the staff and nearby liveaboards some practice deploying them, a bit like a fire drill.

Yes maybe I'm paranoid but for the extortionate mooring fees they're charging it's the least they could/should do 🙂

Stop gates are an alternative to stop planks. Permanent gates each side of aquaducts and embankments, designed to swing, or be swung closed in the event of a breach A set at the entrance could seal off the marina more quickly. Most on the system are in an advanced state of decay, which suggests they may not work well, or CaRT think the probability of a breach is so low that the water they would save doesn't justify the expense. The marina would have to budget for a new set every 25 years, or so, at a cost similar to a pair of top lock gates, plus maintenance clearing silt from the cills, so they could stand a chance of working. Good luck with making the case to them.

There is a set of gates in the stop log at Circus Field. They work remarkably well if some scrote runs off the pound outside. Their sills do need to be kept clear of cr@p, stones waterlogged branches etc. though.

When the Bridgewater breached almost two years ago it was quite entertaining watching the local farmers trying to deploy the stop planks.

Some were rotten, some were swollen to a state that they would no longer fit into the slots. I witnessed one guy break his sledgehammer shaft trying to persuade the planks to fit. In addition to the stop planks quite a few builders bags were deployed. It was a good 24 hours before they managed to stem the flow to a satisfactory degree.

Why dont they use plastic planks, I see lots of seats made of this, presumably recycled.

Good points raised, thanks. Given the practicalities and costs of what would be required I suppose I was being a bit naive/optimistic 😊

1 hour ago, LadyG said:

Why dont they use plastic planks, I see lots of seats made of this, presumably recycled.

Good point- no idea probably merely because wood was traditionally used maybe . If properly weighted they ought to be good. Perhaps sealing between planks would not be as effective although they often use plastic behind stop planks now anyway as well as ash.

1 hour ago, LadyG said:

Why dont they use plastic planks, I see lots of seats made of this, presumably recycled.

Weight. Plastic is so much heavier than wood.

(For equivalent strength and stiffness.)

1 hour ago, LadyG said:

Why dont they use plastic planks, I see lots of seats made of this, presumably recycled.

Cost.... have you seen the price of recycled plastic planking. Probably double the cost of wood at least...

9 minutes ago, MtB said:

Weight. Plastic is so much heavier than wood.

(For equivalent strength and stiffness.)

Not sure about the weight, for stop planks if they sink rather than float that would be good thing wouldn't it?

I recently built some decking using good quality composite decking boards. What is obvious with those and recycled timber is it bends far more than wood so needs more support. I think plastic stop planks would simply bend and come out of the slots.

5 minutes ago, MtB said:

Weight. Plastic is so much heavier than wood.

(For equivalent strength and stiffness.)

Depends on the plastic and in particular, what filler is used. Some can be less dense than wood. An advantage of plastic is that it can be formed, or welded into shapes that give it the most strength where needed. Suitable buttresses on the outside can resist the weight of water it is holding. You need to look at stiffness, yield stresses as well, when compared to wood. A plastic stop plank won't look the same as a wooden one, but could be equally, or more effective. Welded steel stop planks might even work. Shaped and buttressed to minimise weight, while giving enough strength and stiffness. Could even have rubber seals at the joints and against the slots.

You need to look at lifting gear, especially if the Marina has an entrance sized for fat boats. The Bridgewater canal has fixed cranes on site at many of their stop plank locations, ready to deploy the in situ wood planks quickly, but, as @Cheshire cat says, it all depends if the system actually works on the day.

On CaRT waters, you can spot eyelets under bridge arches occasionally, once used to lower stop planks off a block and tackle. Modern lifting regs mean they are almost certainly no longer used and CaRT bring in a properly tested and certified crane. The marina will have an ongoing cost on their lifting gear, maintaining it and keeping the paperwork up to date.

Aluminium works well if shaped correctly

Plenty of other materials will work if correctly shaped; the problem is that they range from considerably more expensive than wood to hugely more expensive than wood... ☹️

Wood is actually a very good engineering material, especially where stiffness is needed -- and stop planks are a good example of this. It also doesn't need a lot of expensive shaping/reinforcing or high-tech manufacturing, just a rectangular chunk of wood which anyone can provide. It does have this unfortunate tendency to rot, but this is hardly that difficult to deal with (correct storage).

For this particular task, good old wooden stop planks (suitably stored to keep the rain off) are probably still the best solution... 😊

31 minutes ago, ditchcrawler said:

Aluminium works well if shaped correctly

But very thievable

20 hours ago, BEngo said:

Testing stop planks is bloody difficult. They can really only be easily sealed when there is good flow through them to draw ashes in to the gaps. That means a fair difference of level either side of the planks. Easy to achieve if you are at the head of a lock, rather harder if you are trying to stank a marina off from even a half-mile pound. ... It can be done. Allow at least four hours to get a good seal. Been there, still have the T-shirt earned at Circus Field. Twice.

Yes, watched some C&RT people replacing stopplanks on HNC lk1E

Major palava - planks float when there's water on both sides, which is tricky - but then trying to seal a breach, with a significant flow, would be more even difficult / hazardous

3 hours ago, PeterScott said:

Yes, watched some C&RT people replacing stopplanks on HNC lk1E

Major palava - planks float when there's water on both sides, which is tricky - but then trying to seal a breach, with a significant flow, would be more even difficult / hazardous

yes seen the same issue at a dry dock, which used stop planks. they had to jam them down to stop them floating up, once the dock was emptying, then they could 'ash' them to seal.

6 hours ago, ditchcrawler said:

Aluminium works well if shaped correctly

I thought i'd read somewhere that CRT where trialling or were using some form of metal adjustable stop plank, I can imagine some alloy version being able to be adjusted in length and fairly easy to deploy.

maybe i'm making that up ? :-)

In 2011/12 a serious drought caused the Tring Summit to be closed. The water level dropped a good eighteen inches and in order to protect the marina stop planks were placed under the nearby Newground bridge. They were useless because, according to Waterways, the bed of the canal was uneven.

See the recent installation of stop planks by Keir at the start of the Whitchurch Arm. For some reason, despite there being the usual stock of planks at the junction, they went and bought their own which then had to be cut to length and shaped.

Yes, they float but that helps when removing them, especially if there are onlookers desperate for the navigation to resume! Or no handles have been fitted to hook them out . . .