overplating

[WotEver]

58 minutes ago, Goliath said:

I did botice the boat became significantly more tender which of course it would but again can't compare to its original state.  

That’s counter-intuitive. A new base plate is putting the weight as low down as possible and losing ballast from a few inches higher should only result in a boat that’s (very marginally) less tender. Assuming of course that it’s sitting with exactly the same draft as before. 

[Balder]

39 minutes ago, Captain Pegg said:

Balder,

I note that was your first post so welcome to the forum. Is this just an article you have searched and found or do you have relevant experience to share?

That particular article has been discussed on this forum previously.

JP

I’ve just had a Humber barge surveyed, last week , and had an interesting conversation with said surveyor on overplating. It seems many overplated boat may become uninsurable in the not to distant future.  Thank you for the welcome.

[colinwilks]

3 minutes ago, Balder said:

I’ve just had a Humber barge surveyed, last week , and had an interesting conversation with said surveyor on overplating. It seems many overplated boat may become uninsurable in the not to distant future.  Thank you for the welcome.

That stacks up with a conversation I had last summer with a colleague who is in the CBOA. He stated that overplating (aka "doubling") was outlawed by the Port of London Authority (and presumably Associated British Ports) some time ago. However, I am fairly sure it depends which waterway you're on, and whether the licence is private or commercial, so I'm not sure that in the context of the inland waterways "many" boats are about to become uninsurable, but knowing how insurers love to avoid liability I would notify my insurer if I was contemplating overplating.

[X Alan W]

1 hour ago, blackrose said:

You seem to be suggesting that it's the electrical appliances that are responsible for pitting? You can have as many electrical appliances on a steel boat as you wish and as long as the boat's DC system is correctly wired and the AC system has some form of earth isolation when plugged into shore power then the steel should not suffer any more pitting than a boat without any electrical gizmos. My old narrowboat was badly pitted all over and had to be overplated yet it had never been plugged into shore power as it has no AC system and only a basic DC system. In contrast, my "new" boat has loads of electrical gizmos and has spent a fair amount of its life on shore power. The hull below the waterline still looks new. I realise that there are other variables such as maintenance, but there is no direct correlation between electrical gizmos on board and the amount of hull pitting. That's a myth.

You could well be correct but my question is why back in the day of basically the only  leccy on boats was to start the power unit & a few 12volt lights the curse of pitting was unheard of forward to the 80's & lots of multi volt gizmo's & pitting of leisure boats is rule rather than exception maybe it's incorrect fitting/wiring of the 'leccy' gizmo's as you are convinced it's not that What in your opinion is the cause as with the advent of more Leccy Kit the pitting has become a more or less a some thing that will occur Your thoughts on the cause looked forward to  Modem steel Crap quality ?

[cuthound]

2 hours ago, Balder said:

I’ve just had a Humber barge surveyed, last week , and had an interesting conversation with said surveyor on overplating. It seems many overplated boat may become uninsurable in the not to distant future.  Thank you for the welcome.

This could be because "RCD2" requires the stability tests to be redone if significant changes are made to the hull of the boat.

[Alan de Enfield]

7 minutes ago, cuthound said:

This could be because "RCD2" requires the stability tests to be redone if significant changes are made to the hull of the boat.

Not a lot of people know that - and of those Inland waterway Ex-Spurts that do, claim "say nowt and no-one will know, or even care".

[Balder]

Insurers are bound by what the IIMS recommends. People can kick , scream or wriggle , if the IIMS decide a certain practice is unsafe then the insurers tighten up.

[Mad Harold]

9 hours ago, colinwilks said:

There's a handy calculator for the weight of steel here: 

http://www.steelexpress.co.uk/steel-weight-calculator.html

As a back of fag packet way to calculate how much your boat will sink, when we load our large GU boat we reckon that once the boat is levelled off (i.e. the gunnels are parallel with the water) we will have loaded 18 tonnes, which added to the approx 20 tonnes displacement of the empty boat gives 38 tonnes. After that, every tonne we load puts the boat 1" lower in the water.

Our 57' leisure boat has a displacement of about 16 tonnes so I would reckon that adding a tonne of steel would put it about  38/16 = 2.4" lower.

For illustration, a base plate measuring 7' x 50' x 6mm weighs 1.5 tonnes.

I am working from memory regarding the displacement of the two boats, but the 1" per tonne on the big one is right, so I think the logic of the calculation holds.

Just used the calculator suggested by Colin Wilks,and overplating my hull sides and bottom the increase in weight [30ft boat] is about 1.3 tons.[Proper tons not metric ones]

I have also read the article suggested by Balder and was quite horrified! 

Does anyone  know roughly how much extra cost is involved in cutting away the old steel before welding new steel to the frames?

I have a horrible feeling that it would make my boat beyond economic repair.

[Bee]

Looks like the days of steel boats could be over then. Ho Hum, back to GRP. Actually if I ever have to cut out plates on my boat I would give some thought to bolting new plates onto the frames at least.

[mrsmelly]

3 hours ago, Balder said:

I’ve just had a Humber barge surveyed, last week , and had an interesting conversation with said surveyor on overplating. It seems many overplated boat may become uninsurable in the not to distant future.  Thank you for the welcome.

Did you buy Balder from Nottingham perchance?

[Sea Dog]

44 minutes ago, Balder said:

Insurers are bound by what the IIMS recommends. People can kick , scream or wriggle , if the IIMS decide a certain practice is unsafe then the insurers tighten up.

IIMS? Really?  I've never of heard them being held in any particular high regard.  As I understand it, they sell correspondence courses and qualify their students as marine surveyors without any practical content to their education.  Of course, many surveyors accredited by them produce recognised survey reports, but do they as an organisation carry any real authority when it comes to setting standards? 

[MtB]

9 hours ago, Balder said:

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

 

Well what an interesting link. Thank you. Expands into detail all the reasons I have held on here that overplating (or doubling) is a fine ol' bodge and not to be relies upon. 

One sloppy statement from the link I would appreciate Balder's views on is the following

"The mild steel fitted should also be of ship building quality."

What specification plate precisely, is "of ship building quality" please? Specfically, what precisely should one ask for when ordering from the steel stockholder? The 'quality' of steel has been discussed at length here many times in the past with few conclusions reached.

Edited December 28, 2017 by Mike the Boilerman

[cereal tiller]

18 minutes ago, Mike the Boilerman said:

 

Well what an interesting link. Thank you. Expands into detail all the reasons I have held on here that overplating (or doubling) is a fine ol' bodge and not to be relies upon. 

One sloppy statement from the link I would appreciate Balder's views on is the following

"The mild steel fitted should also be of ship building quality."

What specification plate precisely, is "of ship building quality" please? Specfically, what precisely should one ask for when ordering from the steel stockholder? The 'quality' of steel has been discussed at length here many times in the past with few conclusions reached.

EN43A is the Spec.

[MtB]

5 minutes ago, cereal tiller said:

EN43A is the Spec.

 

Thanks.

Can you cite a reference for that please?

[cereal tiller]

5 minutes ago, Mike the Boilerman said:

 

Thanks.

Can you cite a reference for that please?

Me.

[Captain Pegg]

50 minutes ago, Mike the Boilerman said:

 

Well what an interesting link. Thank you. Expands into detail all the reasons I have held on here that overplating (or doubling) is a fine ol' bodge and not to be relies upon. 

One sloppy statement from the link I would appreciate Balder's views on is the following

"The mild steel fitted should also be of ship building quality."

What specification plate precisely, is "of ship building quality" please? The 'quality' of steel has been discussed at length here many tiimes in the past with few conclusions reached.

There is no specific mild steel grade for ship building. This is something recently confirmed by Martin Kedian.

However I believe a steel plate used in ship building will have a more stringent set of requirements for straightness, thickness, residual stress, surface preparation and cutting. None of which I suspect is critical in a narrowboat.

31 minutes ago, cereal tiller said:

EN43A is the Spec.

"Was the spec" might be closer to the truth. That would be S275 in modern speak but it's still the same ordinary mild steel; as also used in the vast majority of general construction and 99%+ of all steel narrowboats ever built.

JP

Edited December 28, 2017 by Captain Pegg

[MtB]

 

24 minutes ago, Captain Pegg said:

There is no specific mild steel grade for ship building.

 

Thank you and just as I thought.

Which is why I asked Balding to expand on the sloppy statement, and pressed CT to cite a source for his assertion.

(I am imagining Balding is the author of the report he linked to.)

 

(Spelling edit.)

Edited December 28, 2017 by Mike the Boilerman

[Captain Pegg]

2 minutes ago, Mike the Boilerman said:

 

 

Thank you and just as I thought.

(I am imagining Balding is the author of the report he linked to.)

 

(Spelling edit.)

That thought crossed my mind too.

I will await the list of boats that has sunk through poor overplating, or indeed being made from the proverbial 'crap steel'.

JP

[MtB]

4 minutes ago, Captain Pegg said:

I will await the list of boats that has sunk through poor overplating,

 

My opinion is rather the inverse of this.

I hold that 99% of all boats overplated would have continued to float for another 20 years with no action taken. Consequently overplating (no matter how good or bad) makes no difference.  And by and large the overplaters know this, so most overplating is done just for appearances and is cosmetic only.

[Captain Pegg]

1 minute ago, Mike the Boilerman said:

 

My opinion is rather the inverse of this.

I hold that 99% of all boats overplated would have continued to float for another 20 years with no action taken. Consequently overplating (no matter how good or bad) makes no difference.  And by and large the overplaters know this, so most overplating is done just for appearances and is cosmetic only.

Well mine was overplated at 18 years old over 30 years ago. I have no idea why but I am doubtful it really needed doing. The back of the swims are still 1/4" steel that hasn't been overplated.

 

[X Alan W]

10 hours ago, cereal tiller said:

EN43A is the Spec.

In the past that was the Marine steel plate in the 70's premier div builders quoted that hulls were constructed in 43A plate If this was better I know not

In an earlier post I put forward the thought that extra leccy on boats was seemingly the only difference to bring in the march of the overplate machine Black rose posted that this is indeed not the cause & Ive asked what he thinks is the cause My JOSHER motor was composite build in 1914 when I bought in 1958 it had some half doz 4" square patches over the side plates over where the sides had worn thin over the knees near the bottoms it had no anodes & still didn't in 72 when I sold it I have no idea of the mileage  when owned by FMC & BW but know I did a good few 1000's both as trade & hotel work but it had no trace of pitting & I wonder the reason  Do FMC boats built in the early 1900's now sufferi from plate pitting If yes what folks idea's on the cause

Edited December 29, 2017 by X Alan W

[mrsmelly]

11 hours ago, Mike the Boilerman said:

 

 

Thank you and just as I thought.

Which is why I asked Balding to expand on the sloppy statement, and pressed CT to cite a source for his assertion.

(I am imagining Balding is the author of the report he linked to.)

 

(Spelling edit.)

You may be right about him being the author. I asked him a few posts ago if he had bought Balder from Nottingham which he has read but not replied to? Balder is an old Humber Keel that was used as a liveaboard for many years on a private mooring on the Trent near the Council houses under Trent bridge in Nottingham but it was sold by the elderly owner iirc last year ish and removed. It could be coincidence but................................. Come on Balder cough it up!!

[MtB]

9 minutes ago, mrsmelly said:

You may be right about him being the author. I asked him a few posts ago if he had bought Balder from Nottingham which he has read but not replied to? Balder is an old Humber Keel that was used as a liveaboard for many years on a private mooring on the Trent near the Council houses under Trent bridge in Nottingham but it was sold by the elderly owner iirc last year ish and removed. It could be coincidence but................................. Come on Balder cough it up!!

 

Lol I've just noticed my repeated typo of his username  ... Probably why he isn't aswering!!!

[Captain Pegg]

12 hours ago, Mike the Boilerman said:

 

 

Thank you and just as I thought.

Which is why I... ...pressed CT to cite a source for his assertion.

 

You should never give CT a hard time. He is the forum's most prolific giver of green things.

Merry Xmas and a Happy New Year CT.

JP

[Captain Pegg]

2 hours ago, X Alan W said:

In the past that was the Marine steel plate in the 70's premier div builders quoted that hulls were constructed in 43A plate If this was better I know not

In an earlier post I put forward the thought that extra leccy on boats was seemingly the only difference to bring in the march of the overplate machine Black rose posted that this is indeed not the cause & Ive asked what he thinks is the cause My JOSHER motor was composite build in 1914 when I bought in 1958 it had some half doz 4" square patches over the side plates over where the sides had worn thin over the knees near the bottoms it had no anodes & still didn't in 72 when I sold it I have no idea of the mileage  when owned by FMC & BW but know I did a good few 1000's both as trade & hotel work but it had no trace of pitting & I wonder the reason  Do FMC boats built in the early 1900's now sufferi from plate pitting If yes what folks idea's on the cause

Grade 43A is a standard mild steel grade and by far and away the most prevalent grade of steel in use. It's a fairly safe assumption that any steel boat is built with this grade of steel unless there is clear indication to the contrary. Same it is a safe bet that the steel framed buildings on your local industrial estate are built with it. Nothing specifically 'marine' about the grade of steel at all. Today it would be described as S275 under BS EN 10027 rather than Grade 43 which was its British Standard designation. No actual difference in the metallurgical composition though.

Pitting in steel is known by experience in other industries to be caused by chemical attack and the chief culprit is chloride compounds. That's where I'd start looking for an answer. You have legitimate business ensuring your neighbours aren't throwing out aggressive cleaning chemicals with their waste water. Bleach being the obvious one. Don't use it in your boat.

JP