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Replating on the inside does it effect boats gravity?


Judith Adams

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It is difficult to judge the thickness from a photo, but I've seen worse. If you are going to blast it as you say then you should be able to tell if is does need work or not (or get the Surveyor back if you can't judge for yourself). It's had water lying about inside for a long time, and that's what's caused the rusting. How long ago was it welded in Holland? What's it been doing since then?

I'd be a bit surprised if a welder can make a guaranteed seal with new plate inside that. He'd also be running a weld along each side of those frames, and that could easily loosen a rivet or two as well. Obviously there have been leaks between the cabin and hull that need to be attended to, but that shouldn't be too difficult.

Be as gentle as you can when you do the blasting - you don't want to give yourself extra work unnecessarily. Having said that I've lifted flakey rust like that and found that it was just the rust that was keeping the boat afloat - the bottom looked like a skeletal leaf once I got rid of that. On the other hand we'd been carrying freight in it until we docked it - ignorance is bliss (or can be, sometimes).

Edited by Tam & Di
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Tam & Di

Welder and I spoke about it not being easy to weld in strips. Take your point about gentle blasting. We have someone to do it who specialises in boats we aren't doing it outselves. 

Boat has clearly had a leak. Unsure of when replating was done but we know it was taken out of the water before being brought to UK earlier this year. It had recently been painted with black paint so hard even to guess. 

We had her on water for a while and she didn't sink. Like you said ignorance and all that. 

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To my unqualified eye that interior photo doesn't look like very much rust at all. As others have said I'd book a surveyor to spend an hour with an ultrasonic thickness tester once it's all cleaned up and then you'll have a really good idea what you're looking at. 

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Well, I think that the pictures say that it has been quite extensively overplated and that if the surveyor is happy with it then I would accept his opinion. If the overplating is in reasonable condition then I would just haul it out or dry dock it every 3 years or so and keep it painted, as you say its not a great big thing so the cost will not be too drastic. The inside does indeed look quite heavily scaled and if you attacked it with a great big hammer and chisel you might well find thin bits.  It does look as though there has been leaks between the hull and the top, that does need fixing or the scale on the bottom will keep on growing. As Tam says, Fertan or similar is the stuff. If your surveyor says its ok then trust him, In fact having seen the pics I would not re bottom it, just enjoy it as it is and haul it out every 3 years or so and keep it well painted. Did it have any ballast under the floor? bricks or something? I doubt if it needs much or in fact any more than sufficient to get the propeller under water.

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Thanks Bee. We have found concrete cemented into the sides near the mid to bow section. Again it's crumbling and will need attention. 

Generally, a huge thanks to all for all the advice given it has so helpful. 

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It sounds to me like you're obviously not familiar with the terminology and techniques of naval architecture, and the surveyor either doesn't want to commit to saying/advising something he may later regret, or isn't fully familiar with what you want to do with the boat and how it could be done, if at all. For example, if the boat's hull has been constructed mainly with 2.8mm thick metal plate, and with a low-ish freeboard then arbitarily increasing this to 5mm WILL have a negative effect. So will arbitarily adding height to the cabin, increasing the size of the wheelhouse, fitting it out with more weight than previously, and overplating (ie adding metal of approx same thickness as a patch, as distinct from replating where corroded metal is like-for-like cut out and replaced with uncorroded metal, thus restoring a thinner hull to its pre-corrosion thickness). The "insurance requirement" of 5mm is a bit odd, since by trying to achieve this as a retrofit, it WILL lower the freeboard and this may result in the boat being more likely to sink, not less.

You really need to have it professionally looked at (ie, surveyed) by someone familiar with the age and construction of this kind of boat. It might well be that the boat is designed with 2.8mm (or whatever its impreial, or near, equivalent is) plate and that overplating, replating with thicker, and/or extending the wheelhouse is simply not possible on this boat without extensive redesign to maintain the required or sensible freeboard; or that even simple mods such as adding equipment in an interior refit, jeopardises the design margins, and thus safety, of this boat.

2.8mm plate and length ~30ft sounds very similar to the dimensions of a (for example) Springer Water Bug, which are only a couple of tons, not the 10-15 tons of a narrowboat, thus its not possible to relate the work you are mentioning, to similar work on a larger narrowboat which might be 10/6/4 construction, etc.

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4 hours ago, Judith Adams said:

Thanks Mike

Do you think just patching the corrosion will do? I thought that as the plates are exposed to have it all cleaned and relined with steel. Might be over-kill ? 

 

Basically, you seem to have a boat built from 3mm plating. There's nothing you can do to change that to 5mm for insurance purposes so I think you're stuck with third party insurance unless a specialist DB insurer will accept it. 

The corrosion looks trivial from the photo but its hard to tell for sure without seeing it for real. I'd say all it really needs is rust-proofing treatment on the inside and painting. (And the superstructure leaks fixing, obviously.)

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20 minutes ago, Paul C said:

2.8mm plate and length ~30ft sounds very similar to the dimensions of a (for example) Springer Water Bug, which are only a couple of tons, not the 10-15 tons of a narrowboat, thus its not possible to relate the work you are mentioning, to similar work on a larger narrowboat which might be 10/6/4 construction, etc.

I can't remember off-hand what the hull thickness of a typical Westlander is, but I'd be extrremely surprised that it was 2.8mm. They are work boats carrying freight, admittedly usually fairly light farm produce. Intuitively I'd expect them to be 4mm, but someone on the DBA forum would be able to say more authoritively. I also find it odd that any insurer experienced in UK canal craft would stipulate 5mm - the OP just needs to find an insurer who has Springers on his books and go to them.

Starcoaster on this forum would be a good person to ask.

Edited by Tam & Di
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I would imagine that 4 mm is about right, they were work boats but not banged about like joey boats, they were (I think) boats built for farm produce and the like to take to markets along smaller waterways, poled, sailed, hauled and similar, they would not have had tons of coal or stone dumped into them and dragged through rubbish filled canals wearing out the bottom plating. 2.8mm? that's a funny thickness, is that some odd imperial gauge?  I think I would protect the steel that you have and build up a contingency fund for any problems. That's not because I think it will sink, that's just because its a boat and all my boats have needed a contingency fund, not for the bottom (yet) but for pretty much everything else.

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I have to question the basis of the OP's concern regarding the thickness of the steel (iron?).  What exactly is meant by 2.8mm thickness of replated steel?

Many dutch barges were constructed of relatively thin riveted iron plates and are still good 100 years later.

I haven't seen any objective interpretation of the variation in thickness of the existing hull which should give a clear indication of any corrosion.  It is highly unlikely that the original hull was 4mm thick and it has all corroded so it is now all 2.8mm thick.  It should be borne in mind that the hull form deliberately makes use of curved plates which are many times more stiff (and therefore structurally stronger) than flat plates of the same thickness.  The fact that 'there has been a leak' probably has nothing to do with the hull thickness.

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I put an enquiry about the likely original hull thickness on the DBA forum, and had a reply from one of the most competent surveyors we know. He didn’t answer the question directly but did suggest that measuring the lap seams would give a fairly accurate idea. He did however point out that once it is overplated the original is fairly irrelevant - the only significant layer is the overplating, plus how it is attached to the original and the condition of that original.

He did also say that there is absolutely no way that patches can be put on internally, and that it was unfortunate that a steel cabin had been fitted. He noted that if the height of the cabin was increased the boat would become very tender - i.e. roll alarmingly.

It is fairly easy to see from the inside photo that in the higher section of the  accommodation there is more conversion than there is height of the hull itself. By the time you add the weight of the lining and any insulation you have a very top heavy craft that is bound to roll a lot, and the low sides mean you can’t really add much ballast before the freeboard becomes of concern.

However someone has presumably been living on it in The Netherlands for some time so it’s not impossible. You just need a mooring with no passing traffic causing it to rock. Another possibility (though pretty drastic) is to rip off the steel top and replace it with something lighter. That should allow you to have full headroom throughout.

Presumably it was extremely cheap, but whatever you do it's going to be a lot of work, and a lot of expense even to do the bulk of it yourselves.

I can only wish you good luck with it.

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You have to be careful with these boats, and only get expensive replating done after having studied the possibilities of the use of this boat after all the work is done.

 

To start with, they were built to transport manure and horticultural produce on the tiny ditches between the pieces of land where they were working, they weren't motorised to start with and were moved with a boom, as these ditches weren't deep.

 

As you have noticed their sides are low, they were open boats, and the fairly light cargo went in the hold, and not on top of it.

 

Now with a steel superstructure added, and that by the sound of it, you want to raise even more, to create a bit more headroom, a boat like this will become quickly top heavy, and won't be a safe and stable boat.

 

Don't get me wrong, I'm not trying to scare you off, but only trying to make you realise that this may not be the ideal boat to pump your money in, and then find out that your not happy.

 

As we all know, it's so much easier to get rid of your money, than get some coming in (or is that only my case ? )

 

Good luck anyway,

 

Peter.

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2 hours ago, bargemast said:

You have to be careful with these boats, and only get expensive replating done after having studied the possibilities of the use of this boat after all the work is done.

 

To start with, they were built to transport manure and horticultural produce on the tiny ditches between the pieces of land where they were working, they weren't motorised to start with and were moved with a boom, as these ditches weren't deep.

 

As you have noticed their sides are low, they were open boats, and the fairly light cargo went in the hold, and not on top of it.

 

Now with a steel superstructure added, and that by the sound of it, you want to raise even more, to create a bit more headroom, a boat like this will become quickly top heavy, and won't be a safe and stable boat.

 

Don't get me wrong, I'm not trying to scare you off, but only trying to make you realise that this may not be the ideal boat to pump your money in, and then find out that your not happy.

 

As we all know, it's so much easier to get rid of your money, than get some coming in (or is that only my case ? )

 

Good luck anyway,

 

Peter.

 

With this, Peter has verbalised my own concerns and beaten me to it, expressing them in the kind and gentle way I was trying to think of too.  

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Thanks Peter and Mike, again this is helpful. Reconsidered raising the headroom as  per previous comments on the thread. It is interesting to know their prior use. Wheelhouse construction looks to be of tin or aluminum and so we will replace with similar design and materials. 

Bee - yes we have found the concrete, also corroded or erroded (pick the terminology that fits) and we will renew it  in its original position. 

Thank you for asking the surveyor at DBA that was informative. 

A fascinating conversation so far 

She was not the most expensive boat to buy and we have a budget so we will spend wisely. 

Finding a mooring on a non-tidal river is also tricky but I'm sure we will get the right place for her. BTW she has been renamed "Ugly Duckling" and so she is!  A lovely historic vessel that was clearly well maintained at another time. 

Thanks again 

 

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20 minutes ago, Judith Adams said:

Thanks Peter and Mike, again this is helpful. Reconsidered raising the headroom as  per previous comments on the thread. It is interesting to know their prior use. Wheelhouse construction looks to be of tin or aluminum and so we will replace with similar design and materials. 

Bee - yes we have found the concrete, also corroded or erroded (pick the terminology that fits) and we will renew it  in its original position. 

Thank you for asking the surveyor at DBA that was informative. 

A fascinating conversation so far 

She was not the most expensive boat to buy and we have a budget so we will spend wisely. 

Finding a mooring on a non-tidal river is also tricky but I'm sure we will get the right place for her. BTW she has been renamed "Ugly Duckling" and so she is!  A lovely historic vessel that was clearly well maintained at another time. 

Thanks again 

 

There was no concrete in the original position, there was only (healthy) steel.

 

Peter.

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3 hours ago, Judith Adams said:

Thanks Peter and Mike, again this is helpful. Reconsidered raising the headroom as  per previous comments on the thread. It is interesting to know their prior use. Wheelhouse construction looks to be of tin or aluminum and so we will replace with similar design and materials. 

Bee - yes we have found the concrete, also corroded or erroded (pick the terminology that fits) and we will renew it  in its original position. 

Thank you for asking the surveyor at DBA that was informative. 

A fascinating conversation so far 

She was not the most expensive boat to buy and we have a budget so we will spend wisely. 

Finding a mooring on a non-tidal river is also tricky but I'm sure we will get the right place for her. BTW she has been renamed "Ugly Duckling" and so she is!  A lovely historic vessel that was clearly well maintained at another time. 

Thanks again 

 

Hello Judith, I was just reading your posting again, and I'm ever so worried that you only bought this boat because she was cheap to buy, and you sy that you have a budget.

 

What good is it to have a budget ?  (unless it's unlimited) if you don't know much at all about boats, and you seem to be somewhere where they know about as much as yourself, talking about replating from the Inside, I've never heard anything as crazy to do on such a boat, and I can assure you that I've been around boats for a long long time, and been on (an to) many yards where I've never ever seen jobs like that been done.

 

Do what ever you want to this boat, but my advise is not to invest any money at all on replating of the hull, try to find a piece of land where there's no risk of flooding and put the boat there as an accomodation for guests, as a summer house, shed or whatever, on some decent supports to be stable and safe, and look for a better boat to go cruising in.

 

It's too bad that lots of people get into boats by buying a cheap one to do up, all fine if you can do all the work that's needed yourself, and that you enjoy doing that, but when you have to pay other people to do that work, the cheap boat will end up costing more than the boat you could have bought if you'd been prepared to pay the total amount the one you bought will end up costing, and that most likely will not really satisfy you anyway.

 

Don't think that I'm only a moaning pessimist, I've seen too many people like you, dreaming for a while, until they finally realised what they were doing.

 

But it's your boat and your money, and your life, so you're free to do as you wish, but don't say that nobody warned you.

 

Good luck with making the right decision,

 

Peter.

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