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Canal boat on a tidal estuary.


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There was a narrow boat high and dry on the mud bank right in the middle at Trent falls last week waiting for the tide about quarter of a mile up the Trent . I've always anchored next to the training wall but then I guess my anchor only weighs around 15kg. I thought he got caught accidently but when he waved as we passed he seemed relaxed enough.

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14 minutes ago, Up-Side-Down said:

That was me and no, there was no problem in the wee 'dock' or, prior to that, in the drying harbour which had a muddy bottom. Was there for a couple of years.

 

Thanks, I think that you have given the answer. The only thing I can add is that some narrowboats have the engine bay vents through the outside of the hull while others have them inboard like in the downturn between gunnel and cruiser stern deck. Just to minimise the chances of a problem, I would go for the latter method.

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Posted (edited)

Thank you all your insightful answers to my question. It certainly has answered a lot of my questions and given me some ideas and food for thought. Hopefully I will be able to come back to here in a few years time and let you all know how it went. Happy and safe boating to you all.

Edited by Shaky Start
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I am wondering why someone would want to transport and moor a narrowboat in an estuary so far from navigable canals? It seems akin to fairly permanently  mooring a widebeam boat on a section of the Worcester and Birmingham canal? 

 

I feel I am missing something somewhere?

 

In terms of not sticking in the mud why not sling two tyres under the hull fore and two aft with stainless lines so each lie under the hull, in two sets of two. It would keep her off the mud largely. 

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12 minutes ago, Stroudwater1 said:

I am wondering why someone would want to transport and moor a narrowboat in an estuary so far from navigable canals? It seems akin to fairly permanently  mooring a widebeam boat on a section of the Worcester and Birmingham canal? 

 

I feel I am missing something somewhere?

 

In terms of not sticking in the mud why not sling two tyres under the hull fore and two aft with stainless lines so each lie under the hull, in two sets of two. It would keep her off the mud largely. 

Is this question directed at me or Shaky Start?

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Once he has had his fill of canals it seems he wants to moor the boat way up the  estuary in a place that although tidal is much more like a river. Perhaps he already has mooring rights. I think he then intends to potter about the upper reaches, and as long as he changes his anodes for zinc I don't see much wrong with that as he seems to know the waters. Probably far less danger than  on the tidal Trent, Severn or the Wash

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10 hours ago, Alan de Enfield said:

 

You have a 'tender behind' and arrive / depart whilst there is still water available,

Many steam railway locos had a tender behind, that's why they didn't sit down.  

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If you pass a nice thick rope under the boat and up both sides with the two ends and tie a nice bow on top, and if you feel the boat being held down by mud suction climb up, untie the bow grasp both sides of the rope and haul about on the rope, up and down the hull jiggling it with a sawing motion to break the suction and release the boat.

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12 hours ago, Alan de Enfield said:

 

It would very much depend on the bottom - if it was sand /gravel / shell you may be OK, but mud / ooze would be a problem.

 

You would need to ensure that 2 people were on board at each tide.

 

Run a rope under the bow and with a person on each side, as the tide comes in you 'saw' the rope side to side pulling slightly towards the stern as you do so.

This will generate a small gap allow the water to fill it and will break the vacuum.

 

Best advice - do not put a flat bottomed boat on a drying mooring, but you could always have some short bilge-keels weded onto the base plate to keep it out of the mud.

 

We have our boat at Plymouth and we have seen some fun and games on the drying moorings.

 

When a group of boats stayed in Dartford lock for a week or so (back in 2018) we always had a skipper on duty to make sure the boats floated off on each rising tide.  The latter third of this blog gives a bit more detail (I was rather pleased with the inclinometer...)  

https://scholargypsy.org.uk/2018/05/29/fc3-dartford/

Edited by Scholar Gypsy
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11 hours ago, Alan de Enfield said:

 

How would that work as the boat floated and swung around with the tide / currents.

Mooring at sea is very different to tying up on a canal tow-path.

 

This plot shows my boat movement at anchor over (I think) a 14 hour period each red dot is a movement. We travelled 2.36 miles over the period, whilst attached to 25 metres of chain.

 

Anchor-Movements.jpg

Out of interest have you tried doing the same recording with the gps unit in a fixed position? 

 

I'm sure you know this but there will not only be one dot. 

 

 

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13 hours ago, Stroudwater1 said:

I am wondering why someone would want to transport and moor a narrowboat in an estuary so far from navigable canals? It seems akin to fairly permanently  mooring a widebeam boat on a section of the Worcester and Birmingham canal? 

 

I feel I am missing something somewhere?

 

In terms of not sticking in the mud why not sling two tyres under the hull fore and two aft with stainless lines so each lie under the hull, in two sets of two. It would keep her off the mud largely. 

 

Apologies for the delay in answering, life got in the way yesterday. I know on the face of it this sounds out of the norm. We are buying a canal boat and want to travel the inland waterways of England for 3 years. Over the 3 years we intend to fit out the interior of the canal boat to our liking, making it a home. We then want to low load it back to Penryn where we currently live and have it put in the water at the top of Penryn river. Then we intend to live on it. The reason why we want to do this is purely for space reasons aboard. The equivalent length motor cruiser or yacht doesn't have the same internal space due to their configuration. We have haulage interests in our family and also mooring interests in Penryn so the the logistics of putting into the water aren't a concern. So this question was purely about the dynamics and potential problems of a flat bottomed bottom sticking to tidal mud at low tide. I have had so very good answers to this potential problem, including yours, thank you.

12 hours ago, Tony Brooks said:

Once he has had his fill of canals it seems he wants to moor the boat way up the  estuary in a place that although tidal is much more like a river. Perhaps he already has mooring rights. I think he then intends to potter about the upper reaches, and as long as he changes his anodes for zinc I don't see much wrong with that as he seems to know the waters. Probably far less danger than  on the tidal Trent, Severn or the Wash

 

You are exactly right Tony. Except we don't intend for the boat to move. In essence it will become a house boat.

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Not sure if anyone has already mentioned this, but in general the baseplates of narrowboats aren't painted by builders because modern narrowboats have 10mm thick baseplates and sit in fresh water (and the builders can't be bothered to paint them!) But if you're having a steel boat built and it's going to sit in brackish water some of the time then make sure that the builder paints the base plate and every other part of the underwater hull with several coats of epoxy paint - bitumen based paint won't last any time at all in those conditions.

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I suspect the steel/iron sailing barges up the east coast are not epoxy coated. It looks like bitumen or tar blacking to me. They sit in the mud at each tide.

Edited by Tony Brooks
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39 minutes ago, Tony Brooks said:

I suspect the steel/iron sailing barges up the east coast are not epoxy coated. It looks like bitumen or tar blacking to me. They sit in the mud at each tide.

Good point Tony!

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3 hours ago, Tony Brooks said:

I suspect the steel/iron sailing barges up the east coast are not epoxy coated. It looks like bitumen or tar blacking to me. They sit in the mud at each tide.

 

You might be surprised. Pitch epoxy looks a lot like bitumen - intentionally.

 

Anyway, whatever is used on old barges is up to the owners, but given the choice one would be stupid not to have a steel boat for use on brackish waters epoxy coated, including the baseplate.

Edited by blackrose
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Recently been sprucing up a little 16' sailing boat that has sat on a tidal mud berth in a creek for the last twenty years or so. It's GRP but has steel bilge keels. After hauling it out this year and scraping the keels down it was pleasantly surprising how little rust there was on them. They looked a real bubbly rusty mess but once scraped back, only a very small amount of material came off before they were back to bare metal. Have just painted them with four coats of bitumen paint but for a NB hull, I'd imagine epoxy from new would be eminently sensible and a better option. My only worry would be damage to the coating from the repeated settling of the boat on the bottom. Although the steel keels hadn't suffered much, the same couldn't be said of the aluminium (or some alloy) skeg and rudder. Corrosion had eaten through the things and when they were cleaned off a couple of big holes emerged that needed filling with ally plate core and polyester filler.

 

It does seem wise for the OP to be considering some way of breaking the suction effect. Mud's sticky and there's a lot of surface area on a baseplate. Would it be possible to sling half a dozen big sleepers under the boat with ropes so that the boat lifts and then settles onto them? They could even have a wedge shape to them or have them different sizes to suit the particular permanent mooring spot so the boat is as level as you can get it when it takes the ground. A lot of tidal moorings leave boats sitting at odd angles when they dry out. As long as it's not a swinging mooring (which it isn't for the OP) it should be possible to improve this with things under the boat and reduce any suction effect at the same time..

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On 28/07/2021 at 07:34, Loddon said:

Yes is a quick answer.

It's by no means certain it would happen but it is possible.

Narrow boats that used to moor on the tidal bit behind Three Mills used to use ropes connected from the offside of the boat under the boat to the floating pontoon to "roll" the boat out of the mud if it did stick.

 

 

Narrowboats at low tide on the Three Mills Wall River, the moorings are no longer tidal.

 

3m.JPG

Edited by Tim Lewis
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6 minutes ago, Tim Lewis said:

 

Narrowboats on the Three Mills Wall River, no longer tidal.

 

3m.JPG

I believe that shelf was built to prevent, or at least minimise, mud-sticking instances - as can be seen once off the shelf there is a greater depth of uneven, glutinous stuff.

As an aside there was an unhly row between BW and Crown Estates about who owned the bed

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Contrary to what one might think, the chances of a flat bottom boat being held down by suction is in my experience vanishingly small.

 

Moored on the saltmarsh in Tollesbury Essex where the mud is incredibly sticky and deep, there is a flat bottomed widebeam of 60' length and 14' beam that sits high and dry on the smooth, flat mud and lifts from it twice every day with the tide with barely a squelch.

 

In the ten years that it has been there it has never shown the slightest sign of reluctance to lift in over 7000 tides, but I have known it make a sucking noise before bobbing up by perhaps an inch or two.

 

East coast mud is legendary for its stickiness, so apart from clay, which might create superior suction, this real life example would suggest that being swamped on a rising tide is, to say the least, extremely unlikely.

 

 

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