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Pitting


JRT

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Some may remember that a while back I asked if I should get a survey done on a narrowboat I was thinking of buying even though it had been blacked this year. Everyone said yes so that's what I've just done - had a full out of water survey done on a boat I had made an offer on subject to survey. I'm glad I did!

 

The survey on this 2005 57ft boat has now been done. It has revealed a few minor faults but also a major issue - the hull is suffering from widespread pitting. Not enough that insurance would be refused but enough to be of serious concern. The surveyor has recommended that the hull is shot blasted and then, at the very least, blacked with two-pack. I trust his judgement and advice (and he has a good reputation on this forum) so I guess I'll reduce my offer to cover the cost or get the vendors to pay for the remedial work.

 

What do people think? Will the remedy work?  (The boat is fitted with a galvanic isolator). Could the pitting get worse.? Am I right to reduce the offer? What should I do if the vendor won't accept the reduced offer?

Should I walk away now?

 

All advice gratefully received! 

 

JRT

 

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The value of the boat will be severely affected both now and when/if you want to sell. Bear that in mind.

I would seek a substantial reduction to cover the cost of spot pit welding all over the hull, grit blast and Zinga preferably but at least epoxy blacking.

 

If not accepted and you are not convinced that you will not worry about the hull in the next few years,, walk away.

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1 hour ago, JRT said:

Some may remember that a while back I asked if I should get a survey done on a narrowboat I was thinking of buying even though it had been blacked this year. Everyone said yes so that's what I've just done - had a full out of water survey done on a boat I had made an offer on subject to survey. I'm glad I did!

Sometimes the advice given is worth a lot more than was paid for it.

 

Well done for following the advice, unless you get the pitting filled then it will still be a pitted hull when you come to sell it.

You need to get a large enough discount to pay to have a welder fill all of the pits.

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I bought a boat from a guy, who, when he bought it, found bad pitting (4mm pits in a 12.5mm base plate),. The reason for the pitting was identified and the boat removed from the 'problem' site. He then had it thoroughly  cleaned and then two-packed, including the base plate. In his history of owning it, and then during my ownership, every time the boat came out, it was two-packed and the pitting inspected. It never (over the course of about 10-12 years) got any worse. This is the main reason I am an advocate of base plate blacking.

In your case, provided the remedial work was properly done, a price reduction made to cover it,  and your surveyor passes it as OK, I'd go for it if it is the boat that fits your requirements. I would, however, try and find out why it pitted so badly in the first place. And make sure next time it comes out in a few years that the pitting is no worse.

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The two pack solution is now being pursued by surveyors following this years Insurance company meeting.

 

"The surveyor has recommended that the hull is shot blasted and then, at the very least, blacked with two-pack"

I have seen this on almost all surveys this year...regardless of pitting.

Every year, they decide on a new directive, last years was mid hull anodes......we even get that recommendation on boats with NO pitting or corrosion.!!!

 

A 2005 boat, if it has been neglected, and in a big marina, will probably now have extensive rashes of galvanic pitting, We are seeing this all the time. Some owners do 3 or 4 year blackings....some dont fit galvanic isolators, some wouldnt know one if it hit them on the head on Christmas Day.

 

I'm not saying get the reduction in price or walk away, what I am saying is that surveyors follow instructions from above, clearly worded, which they add to that and subsequent years surveys to cover their asses. Nothing more.

If you like the boat, dont let it go, its not failed anything other than a annual directive.

 

 

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Thank you everyone for your advice. Most useful. I now have the written report and it states:

 

Base Plate The base plate was originally fabricated using 10.0mm plate
(nominal). Ultrasonic measurements showed the base plate to be
between 10.1mm to 9.6mm.
Pitting was present at up to 1.6mm.
The sacrificial wear edge was found to be free from
excessive wear.
Hull Sides The hull sides were originally fabricated using 6.0mm plate
(nominal).
Ultrasonic measurements showed the sides to be between
6.0mm to 5.7mm.
Pitting was widespread at up to 1.3mm.

 

Is that better or worse than expected? The majority opinion seems to be walk away. Is that still the case?

 

Thanks

 

JRT

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2 minutes ago, JRT said:

Thank you everyone for your advice. Most useful. I now have the written report and it states:

 

Base Plate The base plate was originally fabricated using 10.0mm plate
(nominal). Ultrasonic measurements showed the base plate to be
between 10.1mm to 9.6mm.
Pitting was present at up to 1.6mm.
The sacrificial wear edge was found to be free from
excessive wear.
Hull Sides The hull sides were originally fabricated using 6.0mm plate
(nominal).
Ultrasonic measurements showed the sides to be between
6.0mm to 5.7mm.
Pitting was widespread at up to 1.3mm.

 

Is that better or worse than expected? The majority opinion seems to be walk away. Is that still the case?

 

Thanks

 

JRT

 

Unless you moor in a marina with 'leaky-electrical-worms' and don't take preventative measures, it will easily last out your lifetime

 

Its a bit like have a 999 year leasehold on a house, the first few generations of occupants have no problems getting a mortgage, but as the leasehold gets below (say) 100 years it starts to get more difficult to sell.

To some, a 5.7mm side with 1.3mm pits (leaving it at 4.4mm) mean it will be getting towards uninsurable in the 'near future'.

 

Personally I'd

 

1) Get a quote for filling the pits and negotiate that cost (£1000s ?) off the asking price.

2) Walk away.

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That is still a lot of steel left.  The thing is to do something to stop the pits deepening. In my casual experience - not proper science, just looking at bits of old steel - pits with paint in them become inactive. New pits will still occur and so on but frequent docking, high pressure washing and sanding of the surface followed by at least two coats of epoxy is probably the best way to keep the water out. I wonder about filling the pits with epoxy filler? should work (and make the next surveyor think the thing is pit free) but I have never heard of it being tried, that horrible microbial thing can still occur under filler though, I have seen a boat (not a narrowboat) filled for appearance below the waterline and several years later after some hull work the horrid microbes had been busy under the filler. You are not alone though, many or most of us have pitted steel, we just haven't looked hard enough.

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7 minutes ago, Bee said:

that horrible microbial thing can still occur under filler though,

And, under paint and/or blacking, once 'caught' it takes some killing.

 

 

If a hull is found with evidence of microbial attack, it is necessary to deal with it to try to prevent it recurring. A simple solution is for the whole area to be washed with copious amounts of high pressure fresh water. When dry the area affected should be coated with a strong bleaching agent (sodium hypochlorite) diluted 1:4 with water and left for twenty four hours. Afterwards a second high pressure fresh water wash is necessary followed by recoating. This will probably remove around 90% of the microbes but the only real solution is to blast back to bare steel and to treat any inaccessible areas such as tack-welded rubbing strakes as best one can with the bleach solution before applying the next stage of the coating process. 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..

 

 

Microbial Corrosion.jpg

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That's very interesting, but we don't actually know that the OP's prospective boat is suffering from microbial attack and it seems like we're all equally susceptible to that form of corrosion.

 

It's good that you got the boat surveyed and just shows the problems that a bit of fresh paint can hide.

 

If the pitting is widespread I'm not sure how practical it would be to weld each pit? Personally if you can get the price reduced to cover to cost of docking, grit blasting and several coats of epoxy then that's what I'd do. Make sure you can find somewhere in the area that can actually do this work, has good reviews and understands how to apply the epoxy. 

 

I can recommend a couple of coats of Jotamastic 87 or 90 (both with aluminium) for this job, finished with two coats of the same epoxy without aluminium. I don't think Jotamastic 90 is prone to chalking (turning from black to grey) as 87 does, but you can always use Jotamastic Hardtop for the final coats if that concerns you. 

 

https://www.avace.co.uk/product/jotun-jotamastic-90/

 

https://www.pandsmarine.co.uk/wp-content/uploads/2019/04/Jotamastic_90_Aluminium_data.pdf

 

https://www.jotun.com/Datasheets/Download?url=%2FAG%2FAG__16560__Jotamastic+90__Euk__GB.pdf

 

Jotamastic aluminium can be tinted in different colours which is handy to see exactly where you've painted the first and second coats.

 

Silver tint

027.jpg

 

Pink tint

032.jpg

Edited by blackrose
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26 minutes ago, blackrose said:

That's very interesting, but we don't actually know that the OP's prospective boat is suffering from microbial attack

Correct - I was simply responding to Bee's comment that it can live 'under filler' by pointing out it can live under Epoxy coating, normal paint and Bitumin Blacking as well.

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6 hours ago, Alan de Enfield said:

And, under paint and/or blacking, once 'caught' it takes some killing.

 

 

If a hull is found with evidence of microbial attack, it is necessary to deal with it to try to prevent it recurring. A simple solution is for the whole area to be washed with copious amounts of high pressure fresh water. When dry the area affected should be coated with a strong bleaching agent (sodium hypochlorite) diluted 1:4 with water and left for twenty four hours. Afterwards a second high pressure fresh water wash is necessary followed by recoating. This will probably remove around 90% of the microbes but the only real solution is to blast back to bare steel and to treat any inaccessible areas such as tack-welded rubbing strakes as best one can with the bleach solution before applying the next stage of the coating process. 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..

 

 

Microbial Corrosion.jpg

Is this a photo of microbial attack or rust spots?

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8 minutes ago, XLD said:

Is this a photo of microbial attack or rust spots?

Microbial attack.

There are two types (both boat killers)

 

The picture I posted is 'type 1'

 

1) GALLIONELLA FERRUGINEA Characteristically leaves a fairly shallow pit of approximately oval shape and a ‘rusticle’ made of ferrous and ferric hydroxide. This is a brown non-toxic insoluble powder with black streaks. It is not rust though a marine surveyor has described it in one of his reports by the curiously contradictory name of ‘living rust’. The name ‘rusticle’ was given to the detritus by Dr. Ballard when he found extensive amounts of the stuff on the wreck of the Titanic. It is commonly found on narrow boats and other canal barges in the form of an orange bloom or paste-like phenomenon, often in rings around deeper pits formed by the thiobascillus ferrooxidans corrosion (see (2) below. Being easily washed off, the orange corrosion is frequently considered to have been eradicated. Not so.

 

2) THIOBASCILLUS FERRO-OXIDANS Often closely associated with the gallionella species, thiobascillus ferro-oxidans is a sulphur oxidizing bug (SOB). This leaves a similar pit to the gallionella species but with vertical stepped sides and the flat bottom covered with a hard silver-white substance. The latter is tetra hydrated ferrous sulphide and is non-toxic. It appears not to rust but will eventually start to discolour.

 

 

 

 

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.

Edited by Alan de Enfield
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29 minutes ago, Alan de Enfield said:

Microbial attack.

There are two types (both boat killers)

 

The picture I posted is 'type 1'

 

1) GALLIONELLA FERRUGINEA Characteristically leaves a fairly shallow pit of approximately oval shape and a ‘rusticle’ made of ferrous and ferric hydroxide. This is a brown non-toxic insoluble powder with black streaks. It is not rust though a marine surveyor has described it in one of his reports by the curiously contradictory name of ‘living rust’. The name ‘rusticle’ was given to the detritus by Dr. Ballard when he found extensive amounts of the stuff on the wreck of the Titanic. It is commonly found on narrow boats and other canal barges in the form of an orange bloom or paste-like phenomenon, often in rings around deeper pits formed by the thiobascillus ferrooxidans corrosion (see (2) below. Being easily washed off, the orange corrosion is frequently considered to have been eradicated. Not so.

 

2) THIOBASCILLUS FERRO-OXIDANS Often closely associated with the gallionella species, thiobascillus ferro-oxidans is a sulphur oxidizing bug (SOB). This leaves a similar pit to the gallionella species but with vertical stepped sides and the flat bottom covered with a hard silver-white substance. The latter is tetra hydrated ferrous sulphide and is non-toxic. It appears not to rust but will eventually start to discolour.

 

 

 

 

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.

I remember my narrowboat had lots of these orange crusty spots, which, when removed, revealed bright silver areas.

Is this what you are talking about?

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Once again everyone, thank you for all your advice.

 

The boats needs about £1500 of boat safety things doing to it and the surveyor is adamant that the only way to stop the pitting getting worse is shot/grit blasting followed by 2pack blacking. The latter costs somewhere between £3-4K. The vendor/brokerage have offered me a reduction in the sale price but not enough to cover these costs. The brokerage has also said I should buy the boat at the reduced rate then they'll do the BSS stuff for me and I pay. That sounds a little dodgy to me because I then own an unsafe boat boat and are at their mercy for the work, not to mention mooring fees. Besides isn't it illegal for a brokerage to sell an un-safe boat?

 

So, unless the cost is reduced some more I think I'll walk away which is a shame as I really liked the boat.  I'll have lost the survey fees but I don't want to sit on the boat for the next few years worrying about the hull! Do you think I'm being wise or ridiculously cautious?

 

Thanks.

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22 minutes ago, JRT said:

Besides isn't it illegal for a brokerage to sell an un-safe boat?

No

 

If they are the owner, then they have a legal responsibility to ensure that it 'as advertised' and fit for purpose. if they are selling it simply as a broker on behalf of a private seller, then they have no legal responsibility to tell you about any faults or any responsibility if 30 seconds after you hand over your money it bursts into flames, explodes and sinks.

 

This is the reason why some brokers simply lie and claim that boats they are selling are not owned by them, this allows them to walk away from all responsibilities.

 

It is called 'Caveat Emptor' (Let buyer beware)

Edited by Alan de Enfield
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34 minutes ago, Alan de Enfield said:

No

 

If they are the owner, then they have a legal responsibility to ensure that it 'as advertised' and fit for purpose. if they are selling it simply as a broker on behalf of a private seller, then they have no legal responsibility to tell you about any faults or any responsibility if 30 seconds after you hand over your money it bursts into flames, explodes and sinks.

However, if a survey picks up safety or insurance relevant bits , some have a moral responsibility to inform anybody subsequently viewing (following you walking away), of the faults picked up.

This means that with reputable brokers, the boat problems will be solved either by price reduction reflecting work needed, or the current owner having the work done anyway.

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14 minutes ago, matty40s said:

However, if a survey picks up safety or insurance relevant bits , some have a moral responsibility to inform anybody subsequently viewing (following you walking away), of the faults picked up.

This means that with reputable brokers, the boat problems will be solved either by price reduction reflecting work needed, or the current owner having the work done anyway.

 

The broker has a legal responsibility to reply honestly (to the best of his knowledge) to any direct & Specific question - such as 'does the bilge pump work', but not 'do the elctrics work'.

or

"Has this already had a survey ?", but, not to a 'did it fail a survey ?' (a survey is simply a condition report, there is no pass or fail involved)

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1 hour ago, JRT said:

Once again everyone, thank you for all your advice.

 

The boats needs about £1500 of boat safety things doing to it and the surveyor is adamant that the only way to stop the pitting getting worse is shot/grit blasting followed by 2pack blacking. The latter costs somewhere between £3-4K. The vendor/brokerage have offered me a reduction in the sale price but not enough to cover these costs. The brokerage has also said I should buy the boat at the reduced rate then they'll do the BSS stuff for me and I pay. That sounds a little dodgy to me because I then own an unsafe boat boat and are at their mercy for the work, not to mention mooring fees. Besides isn't it illegal for a brokerage to sell an un-safe boat?

 

So, unless the cost is reduced some more I think I'll walk away which is a shame as I really liked the boat.  I'll have lost the survey fees but I don't want to sit on the boat for the next few years worrying about the hull! Do you think I'm being wise or ridiculously cautious?

 

Thanks.

If there is a niggle in your mind you will never love the boat. I would try to negotiate a price to cover the work completely or walk.

 

I would never let a broker organise work, get your own guys and pay them.

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2 hours ago, JRT said:

Once again everyone, thank you for all your advice.

 

The boats needs about £1500 of boat safety things doing to it and the surveyor is adamant that the only way to stop the pitting getting worse is shot/grit blasting followed by 2pack blacking. The latter costs somewhere between £3-4K. The vendor/brokerage have offered me a reduction in the sale price but not enough to cover these costs. The brokerage has also said I should buy the boat at the reduced rate then they'll do the BSS stuff for me and I pay. That sounds a little dodgy to me because I then own an unsafe boat boat and are at their mercy for the work, not to mention mooring fees. Besides isn't it illegal for a brokerage to sell an un-safe boat?

 

So, unless the cost is reduced some more I think I'll walk away which is a shame as I really liked the boat.  I'll have lost the survey fees but I don't want to sit on the boat for the next few years worrying about the hull! Do you think I'm being wise or ridiculously cautious?

 

Thanks.

 

You're doing the right thing. Why shouldn't you be cautious about a significant chunk of your hard earned cash? 

 

There are plenty of boats on the market so don't make the mistake of thinking you wasted the survey fee. If the vendor or brokerage isn't prepared to reduce the price of the boat to cover the cost of remedial work then that survey has saved you a lot of money and grief. People tend to forget about the grief... Suppose the yard doing the two-packing doesn't do a good job, etc? We hear those stories all the time.

 

Your best bet is to have a word with your surveyor (assuming you like his work) and ask if he can do you a deal on another survey. 

Edited by blackrose
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4 hours ago, Mike Adams said:

Does anyone know or have experience if having your boat zinc sprayed, after shot blasting have any effect on the progress of microbial attack? Some zinc compounds have an antiseptic property so I was wondering if this could be an added benefit?

Ask Debdale marina.

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Thanks for your comments and advice everyone - I've 'walked away '. I've lost my survey fees but then I haven't wasted nearly £50K!

 

I won't be buying the boat mainly because the survey revealed significant faults, principal amongst these being the state of the hull. In places the thickness of the hull is within 0.4mm of being uninsurable and although grit-blasting and 2pack epoxy coating may prevent it getting worse, I just didn't want to take the risk. Besides, even if I was to go down the grit-blasting 2 pack route it might reveal the hull to be in an even worse state and/or in a few years’ time I may be left with the need to over-plate the hull thus reducing it’s value and attraction to buyers should I wish to sell it.  All that and the reduction in the asking price didn't come close to covering the cost of the grit-blasting etc and other boat safety issues.

 

One last thing. The brokerage revealed that the boat had been moored in their marina for many years. Hmmm I thought, maybe the severe pitting on the boat is partially their fault! I hadn't the courage to say that out loud though. 

 

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