Is overplating really that bad?

[Dave_P]

This author thinks so:

https://www.iims.org.uk/the-dangers-of-overplating/

what does the forum think?

[rusty69]

Is it really that bad?

No,if the alternative is a sinking boat. Clearly the best course of action is to have the boat replated, but this may be prohibitvely expensive.

I think if you can get a competent welder with experience,it may be the only option.

Re-ballasting is also likely to be required.

Edited September 14, 2017 by rusty69

[cereal tiller]

1 hour ago, Dave_P said:

This author thinks so:

https://www.iims.org.uk/the-dangers-of-overplating/

what does the forum think?

The Article is correct regards Over Plating, have Welded Pits in a few Boats ,low  Fire risk and easy to do.

New Plating is the Proper way to do it.

[Keeping Up]

I recently had to have my boat overplated because there really was no other option available.

To do nothing would have left me with a potential submarine.

To cut out the affected plate (ie the whole length of both sides, from base to waterline) just wasn't feasible. A new boat would probably have been cheaper!

To fill in several thousand pits would have taken months and also would have been ridiculously expensive.

 

End of options!

Yes the boat sits an inch lower in the water - not a problem

Yes it relies on the welds around the edges. The welder was highly competent so I have no option but to trust him.

[rusty69]

5 minutes ago, Keeping Up said:

Yes it relies on the welds around the edges. The welder was highly competent so I have no option but to trust him.

Was it plug welded in the middle too? 

[Rose Narrowboats]

Since RCD2 came into effect in January, overplating is now viewed as significant modification, and therefore the vessel (if CE marked) must be re-certified by an approved body.

Given that the first CE marked boats are now coming up on 20 years old things could get interesting. Paying an "approved body" (I believe there is only one such company in the UK) is likely to be costly - I've heard £3000 suggested as a figure at one meeting - but the alternative (gutting the boat before cutting out and re-plating) is likely to render boats a great many boats beyond economic repair.

Edited September 14, 2017 by Rose Narrowboats

[Iain_S]

The author has clearly come across a really bad over-plating job, and lists its faults in detail. 

I would agree that over-plating an existing over-plate is bad practice, and that the suspect over-plating should be removed, but am not sure how that could result in a "two foot crack in the second over plate". 

" It is a misconception by boat yards and brokers that all vessels that fall below 4 mm plate thickness should be fitted with a doubling plate along those areas."

Perhaps insurance companies should be added to that list?

[X Alan W]

Can I ask if any one knows the insurance company's thinking on some Springer's? as they started life in the region of a mil short of the 4mm from new & around the 50/60's quite a few commercial coastal craft had 3/16 plating

[magpie patrick]

41 minutes ago, Rose Narrowboats said:

Since RCD2 came into effect in January, overplating is now viewed as significant modification, and therefore the vessel (if CE marked) must be re-certified by an approved body.

Given that the first CE marked boats are now coming up on 20 years old things could get interesting. Paying an "approved body" (I believe there is only one such company in the UK) is likely to be costly - I've heard £3000 suggested as a figure at one meeting - but the alternative (gutting the boat before cutting out and re-plating) is likely to render boats a great many boats beyond economic repair.

How does that affect a boat with no RCD? Lutine was built in 1972 (and is overplated)

[rusty69]

Dunno about RCD2,but our boat was overplated by R2D2, we can see-threepio right through the new plating,he made a right Bocce of it.Perhaps he was a wookie.

Edited September 14, 2017 by rusty69

[Rose Narrowboats]

24 minutes ago, magpie patrick said:

How does that affect a boat with no RCD? Lutine was built in 1972 (and is overplated)

If the boat wasn't CE marked in the first place (which obviously yours wasn't) then you can't have it re-examined to ensure that the info in the RCD manual is up to date because there is no manual.

However, there is a school of thought (promoted by the BMF amongst others) that says any new work to an old boat should be to current standards. I don't think anyone is quite clear on what that means yet. I'm not and I spent most of an afternoon on a RCD awareness course last autumn debating it, but I don't recall anyone reaching a clear conclusion.

Short version, pre-1998 boat don't worry about, especially if the work was done before RCD2 came into force in January of this year.

My personal view is that while of course it is preferable to cut out and let in new steel, overplating is a very cost effective of extending the useful life of a vessel by 15-20 years, and of course it doesn't prevent you cutting it all off and doing it properly further down the line when the boat is due for a refit.

[rusty69]

8 minutes ago, Rose Narrowboats said:

However, there is a school of thought (promoted by the BMF amongst others) that says any new work to an old boat should be to current standards. I don't think anyone is quite clear on what that means yet

I am. It means if they ever make it official, there will be lots of people not complying, including myself. 

Edited September 14, 2017 by rusty69

[Keeping Up]

3 hours ago, rusty69 said:

Was it plug welded in the middle too? 

No, each sheet was welded around the edges only. I can't remember which was which, the top was a different sort of weld to the bottom. Luckily the baseplate still protruded far enough that the new plates could sit on it and still be protected.

[Bee]

I think the author of the article is trying to start a debate but has picked a couple of genuinely bad cases to illustrate his point. A new bottom really should not be hung from the edges of the old one. Obviously liable to corrode or even wear away somewhere and then fill the lot with water. Whiskers (?) or D section guards really should be welded top and bottom when the boat was built, this is a problem on riveted Dutch boats, usually above water. you will see wavy pieces of guard along the edges where rust has expanded and forced the metal apart, take off the capping and underneath its perforated. However I have seen boats with 'Butt straps' across joins in welded bottoms and sides and they are effectively bits of doubling, never a problem. If I had a boat with doubled plating - but done well - I would be happy with it but always be thinking that next time there was a problem that area would need cutting out and renewing. As an aside I have seen a boat patched with a temporary plywood patch fixed on, that patch stayed for the best part of 2 years - don't try this at home though!

As far as the RCD is concerned I would forget it, its a repair. So far as extra weight is concerned then just have a look where the holes are and remember that when under way the back can be a couple of inches lower.

Edited September 15, 2017 by Bee
add a bit

[Alan de Enfield]

22 minutes ago, Bee said:

As far as the RCD is concerned I would forget it, its a repair

 

17 hours ago, Rose Narrowboats said:

Since RCD2 came into effect in January, overplating is now viewed as significant modification, and therefore the vessel (if CE marked) must be re-certified by an approved body.

Conflicting advice ?

24 minutes ago, Bee said:

As far as the RCD is concerned I would forget it, its a repair.

And when the 'oooops' moment happens and your insurers refuse to pay out as you have not complied with 'the law' - what then ?

[blackrose]

Seems to me that the best thing to do is keep the hull well maintained and protected against pitting and corrosion (including galvanic isolation if the boat is on shore power) so it doesn't need re-plating or over-plating in the first place.

If you black your boat every couple of years then fine, but the problem is that people use ordinary bitumen paint and then the boat doesn't come out the water for many years. Bitumen just isn't up to the job of long-term protection unless it's reapplied frequently. I had my widebeam gritblasted 3 years ago up to the top rubbing strake to get all the bitumen off. The steel was in very good condition because it had been painted regularly. I applied 4 coats of the best two-pack epoxy I could buy and did the painting myself. The gritblasting cost £350, the paint was £400 and drydock was another £400. Expensive, but a lot cheaper than any future repair. The only thing I didn't do was the baseplate. It's never been painted but after 12 years it still looks fine. 

Edited September 15, 2017 by blackrose

[rusty69]

15 minutes ago, blackrose said:

If you black your boat every couple of years then fine, but the problem is that people use ordinary bitumen paint and then the boat doesn't come out the water for many years. Bitumen just isn't up to the job of long-term protection unless it's reapplied frequently

I agree,bitumen probably isn't up to the job.These days epoxy seems to be the way to go, but was far less common 30 to 40 years ago,when the boats that were built then are coming upto overplating today.

When we bought our boat in 1999,I didn't even consider grit blasting and epoxy coating.I wish I had,as in the next 10 years ours will need some welding work doing.

[Rose Narrowboats]

9 hours ago, Bee said:

Snip

As far as the RCD is concerned I would forget it, its a repair.

But if a boatyard to carries out a "major modification" to a CE marked boat, the boat must be re-inspected and CE marked or they are breaking the law. It has now been made clear that over plating is  a "major modification."

I wonder how big a sacrificial wear protection strip can be.........

23 hours ago, Keeping Up said:

No, each sheet was welded around the edges only. I can't remember which was which, the top was a different sort of weld to the bottom. Luckily the baseplate still protruded far enough that the new plates could sit on it and still be protected.

If you just had the footings overplated and not the baseplate, no need to worry about plug welds - they're to hold the new baseplate to the old one. The sheets on the sides aren't big enough to warrant it,

 

8 hours ago, rusty69 said:

I agree,bitumen probably isn't up to the job.These days epoxy seems to be the way to go, but was far less common 30 to 40 years ago,when the boats that were built then are coming upto overplating today.

When we bought our boat in 1999,I didn't even consider grit blasting and epoxy coating.I wish I had,as in the next 10 years ours will need some welding work doing.

Don't beat yourself up about it - I've seen boats that were built in the 1970s with epoxy coating from new, and believe it or not they have been in worse condition than supposedly otherwise identical spec. boats.

Personally I don't think two-pack is the panacea many people would have us believe. If you are in the position of commissioning a new build, then I think the way to go is to specify a high quality steel in the first place than use boggo EN43 plate and then spend a fortune on snake oil trying to stop it going back to nature.

Edited September 15, 2017 by Rose Narrowboats

[roland elsdon]

Current philosophy in my peer group is simple I'm 60/65 years old, overplate will last 15 years if done well ( bottom only) clean it off overplate and get over yourself. If trump  life or the North Koreans  doesn't kill me first I'll worry again when I am 80 or so..or not.

 

[Captain Pegg]

3 hours ago, Rose Narrowboats said:

Personally I don't think two-pack is the panacea many people would have us believe. If you are in the position of commissioning a new build, then I think the way to go is to specify a high quality steel in the first place than use boggo EN43 plate and then spend a fortune on snake oil trying to stop it going back to nature.

I don't follow that logic. If you are building in steel S275/EN 43 is fine. If you up spec to S355/EN 50 then you get a higher yield strength which you don't need and a lower chromium content which is deterimental to corrosion resistance. I doubt it makes much difference compared to good maintenance so I suspect you would be paying for no benefit. The grade of steel isn't the issue.

My boat was built in 1969 with 1/4" bottom and 3/16" sides. It was overplated in 1987 with 6mm on the bottom and 4mm on the sides. It's still fine so while you all carry on discussing the rights and wrongs of overplating I shall be off boating.

JP

[Rose Narrowboats]

Grade/quality of steel is an issue. I've no idea what spec it was, but the bottom on my boat is also 1/4", 2 years younger than yours, not overplated and note I'm still using the present tense for its thickness. I've got another (shipyard built) all steel welded hull from 1961 which has never had a repair yet, nor is it expected to for many years to come. Neither of those have ever been painted in anything more technical than pitch.

I'm not a chemist, nor an expert on all the grades of steel available (I have a friendly naval architect who is though), but back to simple stuff I can understand and the two ex BWB hoppers I own which might have been painted once in their 45 plus year existence and are still rock solid yet I've worked on other boats built in that era which have been cared for and are knackered.

I recall a brand new widebeam boat around 10 years ago upon which the 20mm thick baseplate delaminated as it was being trimmed off round the swims. All the fancy paint in the world can't fix that.

We're looking at building some hoppers from Corten B, as much for the weight saving, but it will be interesting to see how they hold up corrosion wise.

[nb Innisfree]

I understand that corten steel has to build up a protective patina to resist corrosion, this requires it to dry out regularly, for instance it's not very successful in wet tropical areas so I can' see it working underwater. 

Or am I talking out of my arse? 

[tomsk]

There is begger all wrong with properly executed localised over-plating.

It's obviously not ideal but so long as it's PROPERLY EXECUTED I cant see a problem.

If you have the financial liquidity and time to cut out the bad bits and re-skin then do so, otherwise it's a bona-fide stopgap.

Please don't spend your life plating over a colander though.

 

[jenevers]

Seeing as how most corrosion takes place along the waterline. Is it not a cost effective solution to have say a 300mm band gritblasted all around the hull, and 2 pack painted. I don't see the need to have the sides above the waterline gritblasted or the base plate, which many people say doesn't need painting at all.

[Captain Pegg]

7 hours ago, Rose Narrowboats said:

Grade/quality of steel is an issue. I've no idea what spec it was, but the bottom on my boat is also 1/4", 2 years younger than yours, not overplated and note I'm still using the present tense for its thickness. I've got another (shipyard built) all steel welded hull from 1961 which has never had a repair yet, nor is it expected to for many years to come. Neither of those have ever been painted in anything more technical than pitch.

I'm not a chemist, nor an expert on all the grades of steel available (I have a friendly naval architect who is though), but back to simple stuff I can understand and the two ex BWB hoppers I own which might have been painted once in their 45 plus year existence and are still rock solid yet I've worked on other boats built in that era which have been cared for and are knackered.

I recall a brand new widebeam boat around 10 years ago upon which the 20mm thick baseplate delaminated as it was being trimmed off round the swims. All the fancy paint in the world can't fix that.

We're looking at building some hoppers from Corten B, as much for the weight saving, but it will be interesting to see how they hold up corrosion wise.

Environment and/or maintenance are the key factors. That's why you get such variation in the condition and longevity of hulls. It's likely that all your examples were constructed in ordinary mild steel and therefore would support the idea that the grade of steel isn't the critical factor. If it was then you would see similar condition hulls at similar ages. I see folk use the term "quality" of steel on the forum but I don't know what that really means and I doubt they do either. Mild steel structures are commonplace in far more harsh environments and load carrying conditions than a narrowboat requires.

JP