45ft narrowboat overplating/replating advice (Milton Keynes)

[redmooncaptain]

Hello,

I have a  45ft narrowboat I live on my own. I have a disability, and it's adapted to my needs, so somehow I'm fighting to keep it after receiving bad news.
I had a survey done in 2019 and hull thickness was brilliant. But at the beginning of this year, I had another one that terrified me. It was found in some small places measuring 1.9mm(due to some chemicals they said). And, now, it needs urgent replating. And I'm due to blacking it too, but I don't know what to do. I don't have 15k to overplate it right now(price asked from a marina in London). And it will take at least 1 year for me to save this money. 
It is an old narrowboat (1974), but I really want to keep it since it's all adapted and it would be too stressful to go narrowboat hunting and adapting it again, plus the money. So I'm basically living a nightmare. I just got my breath again and started to think about solutions.

Any general suggestions? I'm finally mentally prepared to start dealing with it. And I know there's not much what you could really say about it without seeing the boat out of the water.

Or does anyone know who could this boat service around the Milton Keynes area or anywhere in Midlands where it could be much cheaper?

I know anyone can't predict the future, and it's a stupid question probably, but do you think I'd have at least a year to save the money to repair the hull before it starts sinking? I know it can be a slow process. But anyway, just curiosity.
 

I'm aware it's a difficult question to answer to someone without enough money to deal with it. And probably some people would suggest selling it this way(which I understand why). But I'm in a temporary money difficulty and it happened at the same time. Soon things will get better though. So that's why I'm trying to calm down and find a solution first.

Thanks!!

Here there are some highlights from the survey:

 
 Base plate –6mm 
 Counter base – 6mm 
 Hull and swim sides – 5 mm. The counter sides were 6mm 

The readings on the transom were in the range of 1.9-4.7mm, 
On the base plate, UTM combined with pit depth measurement in immediate proximity, showed a very considerable metal loss, especially in the chines area. The worst examples were: 
 Aft chines, just forward the engine bulkhead: Station 7A – 2.7mm base plate thickness to starboard and 3.5mm to portside. 
Midships: Station 5 - UTM 4.3mm with 2.0mm pitting to portside and 3.1 mm plate thickness with 2.0mm pitting to starboard. 
Forward chines: - leak (a breach in the water tightness) to starboard.
 

[MrsM]

So sorry to read about your situation. Hopefully you will get some good advice here. 

[Alan de Enfield]

Sorry to hear of the problems and yes you don't need panic just yet - you have some time (but how long is unknown)

 

What were the thickness readings in 2019 for the same areas ?

 

 

If I am reading the figures correctly it looks as if you are down to 0.8mm in some areas, which would suggest you need to act fairly quickly - the boat will not sink until it gets down to 0.0mm but no idea when that will be. If you are cruising then running over a shpping trolly or bumping into the Armco could be a big problem.

 

If you have fully comprehensive insurance it may be worth making the insurance company aware as they will not insure you with yes than 4mm thickness, but may be prepared to work with you.

 

Have you considered taking to a boat yard about staggered payments over (say) 12 months ?

[Arthur Marshall]

My forty footer cost nine grand for new bottom and sides a couple of years ago at Stoke Boats. It was so thin you could see through the hull when they blasted the bitumen off, and they had to weld quite high up as the steel was so bad. That's a lot cheaper than fifteen grand.

[Barneyp]

16 minutes ago, Arthur Marshall said:

My forty footer cost nine grand for new bottom and sides a couple of years ago at Stoke Boats. It was so thin you could see through the hull when they blasted the bitumen off, and they had to weld quite high up as the steel was so bad. That's a lot cheaper than fifteen grand.

The price of steel has massively increased this year ( thanks to the invasion of Ukraine) which would account for the higher price.

[Barneyp]

I think it's important to understand why it corroded so quickly, otherwise it may continue corroding at the same rate, thus reducing the time you have to fix it, or meaning any overplating won't last long.

 

You say you were told the corrosion was down to "some chemicals", what chemicals? and why were they in contact with your boat?

This rate of corrosion isn't normal, if someone has been putting corrosive chemicals in the water near your boat the environment agency will want to know, and you may be able to make a claim against who put the chemicals there.

 

I would have thought the most likely cause of corrosion like this was galvanic corrosion, caused by lack of or a faulty galvanic isolator if you use a shore line. Is this a possibility in your case, if so get it checked out.

[BEngo]

Talk to the Boat Shed at Leighton Buzzard.  Always loads of boats on the bank being plated there.

 

You could also try Michael Patterson at Aylesbury.  He overplated his own boat in the slip at Circus Field.

 

 What sort of hull is your boat?  A Springer? Does it have a flat bottom?  The slip at Circus Field does not accept V bottom craft.

 

It is not clear to me whether the problem is general plate wastage ( thin everywhere)  where a collision with a bridge or  trolley  could cause a real structural problem, or whether it is pitting which is not likely to cause a structural integrity problem in the short term  but might well develop over time into a collection of individually small, but collectively worrying leaks.  That said, most wooden former carrying craft have been known to leak.  The short term solution is a good bilge pump and a careful watch on the bilges.

 

If it is pitting you can get the worst pits welded up, including  the forward chine where there is a leak.  This will be cheaper and give you peace of mind until you can save up for overplating.

 

N

 

[MtB]

1 hour ago, redmooncaptain said:

But at the beginning of this year, I had another one that terrified me. It was found in some small places measuring 1.9mm(due to some chemicals they said). And, now, it needs urgent replating.

 

 

Somehow, this doesn't quite ring true to me. The huge degradation can happen but is unusual, and the bit about chemicals being the cause bothers me in particular and I'm wondering if your surveyor made that up and if he did, what else he might have made up too, and if he really knows how to use his ultrasonic thickness device and those readings are accurate.  

 

With such a variance between the two surveys I'd be wondering about getting a second survey done before shelling out £15k. And if a second survey agrees, I wonder if patching might be a better option given your 'small places' comment. Where you in attendance during the survey? Did you see the thickness measurements taken? 

 

Also where is home for the boat? Are you in a marina or out CCing? Chemicals seem highly unlikely to me to be the cause, IF the results you have really are acurate. 

 

Oh and another question, was it the same surveyor did both surveys?

[Alan de Enfield]

39 minutes ago, Barneyp said:

You say you were told the corrosion was down to "some chemicals", what chemicals? and why were they in contact with your boat?

This rate of corrosion isn't normal, if someone has been putting corrosive chemicals in the water near your boat the environment agency will want to know, and you may be able to make a claim against who put the chemicals there.

 

There are a couple of forum mebers who had even worse corrosion - within 12-18 months thickness readings went from 6+ mm to 2mm, and the other went from 8mm to 3mm and neither source was never found.

 

 

[David Mack]

Kedian Engineering have been recommended on the forum before for overplating. The owner @Martin Kedian    is a member here.

They are based at Southam, away from the canal, so boats have to be trucked there and back, so in your case it may be easiest to get the boat lifted out somewhere around Milton Keynes and taken by road to Kedians.

 

[Barneyp]

2 hours ago, Alan de Enfield said:

 

There are a couple of forum mebers who had even worse corrosion - within 12-18 months thickness readings went from 6+ mm to 2mm, and the other went from 8mm to 3mm and neither source was never found.

.......

The OP did say the surveyor said the corrosion was "due to some chemicals" there may well not be anything behind that claim, but if there is it would be worth following up.

And steps can be taken to prevent galvanic corrosion.

[Alan de Enfield]

3 minutes ago, Barneyp said:

The OP did say the surveyor said the corrosion was "due to some chemicals" there may well not be anything behind that claim, but if there is it would be worth following up.

And steps can be taken to prevent galvanic corrosion.

 

To me that doesn't quite stack up.

Any 'chemical' spill / pollution would be quickly diluted by the volume of water - if it was serious enough then the EA would have been involved.

 

I'dsuggest there is much more chance of it beig MIC (which could be considered to be a chemical attack because the sulphide films produced by MIC are HIGHLY corrosive.

 

Microbially Induced Corrosion (MIC) is a highly unpredictable process but under the influence of micro-organisms, corrosion processes can be rapid, happening in a matter of months compared to the years it would take for ordinary abiotic corrosion to reach serious proportions. This phenomenon is well known in the oil, gas, water and mining industries but is little understood in the steel boating world. MIC frequently occurs in areas with high nitrate content in the water – this particularly pertains to arable regions of the canal network and particularly to canals and rivers on the east side of the UK and where there is intensive crop farming using non organic chemical fertilizers with consequential phosphate, sulphate and nitrate run-off into the watercourses. Marinas fed by rivers are another risk area and, in salt water environments, it is well known that harbour muds are highly contaminated by sulphides produced by these creatures. Sulphide films are, by their very nature, highly corrosive and the identification of such very obvious. It is usually found under muddy and slimy surfaces, sometimes even behind paint coatings and a very careful visual inspection is necessary to locate it. It is not discoverable by non-destructive testing such as ultrasonic thickness measurement, eddy current testing or the magnetic method familiar to most marine surveyors. The bacteria are often found inside oxidised welds or in areas which contain physical defects such as porosity, overlap or lack of penetration. The microbes leading to this condition can both cause corrosion from beneath existing coatings or seek out pinpricks in the steel coating and cause the reaction to occur from the outside. MIC bacteria can be present under previous blackings and is not eradicated by simple pressure washing. Unless correctly treated, MIC can continue to thrive beneath the coating, emerging as major pitting.

 

The main problem is that the microbes can continue to live beneath the existing paint coatings and once sealed in with a fresh blacking, the lack of oxygen and light is the perfect environment for them to thrive leading to a risk of corrosion from the inside out. No coatings are entirely proof against a microbial attack from the exterior. Minute pinpricks, mechanical damage below the waterline are all opportunities for the microbes to penetrate the steel and commence the process from the outside in.

 

Forum members have been sibject to MIC with resultant large losses in steel thickness.

Some forum members deny MIC exists, but, whatever we are discussing there are always those in denial.

 

 

 

[Bod]

Chemical reaction/damage.

Is there any chance that this could have come from the inside?

Leaking battery acid could thin the steel from the inside, which would give thin readings.

 

Bod

[LadyG]

6 hours ago, Barneyp said:

I think it's important to understand why it corroded so quickly, otherwise it may continue corroding at the same rate, thus reducing the time you have to fix it, or meaning any overplating won't last long.

 

You say you were told the corrosion was down to "some chemicals", what chemicals? and why were they in contact with your boat?

This rate of corrosion isn't normal, if someone has been putting corrosive chemicals in the water near your boat the environment agency will want to know, isand you may be able to make a claim against who put the chemicals there.

 

I would have thought the most likely cause of corrosion like this was galvanic corrosion, caused by lack of or a faulty galvanic isolator if you use a shore line. Is this a possibility in your case, if so get it checked out.

I think OP will need to find out more about galvanic corrosion, which is due to the electrical activity and attacks the metal. And can be rapid. I suppose galvanic does involve a chemical reaction, in a way.

As he has had a written survey, he should talk to the surveyor and ask him to explain what is happening. Why it is happening and how to stop it. No one is born with this sort of knowledge, so it's up to the surveyor to give an full explanation in terms anyone can understand.

Interpretation of the readings is difficult, again, the surveyor should be able to help, its his experience one is paying for, OP need not be hesitant in asking for more understanding.

Fingers crossed things are not as bad as you might be 

 currently thinking.

Edited July 5, 2022 by LadyG

[MtB]

11 hours ago, Alan de Enfield said:

There are a couple of forum mebers who had even worse corrosion - within 12-18 months thickness readings went from 6+ mm to 2mm, and the other went from 8mm to 3mm and neither source was never found.

 

 

And there are hundreds, thousands perhaps, of forum members whose boats have not suffered such corrosion, just to add some balance. 

 

Did either poster get their 2mm thickness measurements independently verified? Or did they just accept them at face value and spend five figure sums on overplating?