Pre-Purchase Surveys

[matty40s]

If you dont have a survey, you may well not know that your hull is rotting swiftly away underwater.

This boat came in, after apparently being 2 packed in 2019, so the owners thought it was well protected.

Nothing at all stayed on underwater, and MIC is evident all over the hull.

 

However, it was down to us to point out what it was to the surveyor, who hadnt come across it before!!!

[blackrose]

19 hours ago, David Mack said:

 

Brokers are probably better if you want a survey as they have the contacts and resources to sort it all on behalf of the seller.

 

That in my opinion is a very bad idea if what I'm reading is what you mean?

 

Do not accept a seller's or broker's survey. The only survey that's worth anything is one you commission yourself. Don't even take a broker's recommendation for a surveyor, find the surveyor yourself and if possible avoid divulging the name of the surveyor to anyone involved in the sale of the boat.

 

I hate to sound paranoid but it wouldn't be the first time a surveyor has been "nobbled".

Edited March 22, 2023 by blackrose

[Alan de Enfield]

6 minutes ago, matty40s said:

However, it was down to us to point out what it was to the surveyor, who hadnt come across it before!!!

 

According to quite a number of 'old-hands' on the forum there is no such thing so stop scaremongering !!!

[blackrose]

1 hour ago, matty40s said:

 

This boat came in, after apparently being 2 packed in 2019, so the owners thought it was well protected.

Nothing at all stayed on underwater, and MIC is evident all over the hull.

 

 

This also shows that merely getting a boat epoxied isn't necessarily a long term solution to hull protection unless the hull is properly prepared and epoxy is correctly applied. 

 

Too many people are handing over significant sums of money to yards who employ the rudimentary services of some bloke on minimum wage with an "agricultural" outlook who's used to slapping on bitumen. If you rely on someone who hasn't  read and understood the technical data sheet for the epoxy then you're unlikely to get a good result.

[Alan de Enfield]

7 minutes ago, blackrose said:

This also shows that merely getting a boat epoxied isn't necessarily a long term solution to hull protection unless the hull is properly prepared and epoxy is correctly applied. 

 

 

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.

 

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..

Edited March 22, 2023 by Alan de Enfield

[blackrose]

23 minutes ago, Alan de Enfield said:

 

 

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.

 

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..

 

Yes I'm well aware of MIC. While it's true that no coatings are entirely proof against microbial attack, properly applied epoxy is about the best defense you can get. There should be no pinpricks in properly applied epoxy and mechanical damage should be minimised compared to other paint system's.

[LadyG]

Looking at the photo, I'm surprised the owner did not notice corrosion before it affected the complete hull.

[MtB]

2 hours ago, matty40s said:

This boat came in, after apparently being 2 packed in 2019, so the owners thought it was well protected.

Nothing at all stayed on underwater, and MIC is evident all over the hull.

 

Shocking. Thanks for the photos.

 

How many boats per year do you dock? And of those, how many per year do you see like that? 

 

 

[matty40s]

17 minutes ago, LadyG said:

Looking at the photo, I'm surprised the owner did not notice corrosion before it affected the complete hull.

The coating above the waterline still looked black, although it came off in sheets with the pressure washer, Blackrose is probably correct in his summation of the boatyard who applied the 2pack. 

 

13 minutes ago, MtB said:

 

Shocking. Thanks for the photos.

 

How many boats per year do you dock? And of those, how many per year do you see like that? 

 

 

Probably around a hundred over the whole site, both in our dry dock and outside on the hard standing for surveys and Summer blackings. It's only about the 4th one of these I have seen, 2nd worst.

[MtB]

37 minutes ago, matty40s said:

The coating above the waterline still looked black, although it came off in sheets with the pressure washer, Blackrose is probably correct in his summation of the boatyard who applied the 2pack. 

 

Probably around a hundred over the whole site, both in our dry dock and outside on the hard standing for surveys and Summer blackings. It's only about the 4th one of these I have seen, 2nd worst.

 

Thanks! So the 4th one in the about ten years you've been a boat techy? 

 

I'm just trying to get a feel for how common this is. I don't think it was ever a thing 25 years ago, but now it is. 

 

 

[enigmatic]

12 hours ago, Athy said:

Why should this be?? Most people selling a house wouldn't bat an eyelid if a buyer needed to get a mortgage, and the sums involved can be comparable. In any case, why would Charlotte and Harry need to inform the seller that they had taken out a bank loan. As long as their cheque doesn't bounce, it's none of the seller's damned business where the money came from.

 

If you're selling a house, 95% of buyers are going to be needing a mortgage, they'll generally get a mortgage so long as they have jobs (and a boat-price-size deposit!) and quite possibly have a mortgage agreement in principle, and the whole process takes months anyway. With boats it's the opposite. In this case, it looks like Charlotte and Harry have done the sensible thing and already lined up some financing and found out what the conditions are, but mortgages are a weird anomaly in the boat market and a lot of people that just assume they're going to get mortgages just don't have the money and won't get it either.

 

Same as when you sell a house, you normally end up in a chain, but I don't think there are many people selling narrowboats who'd tolerate that.

 

10 hours ago, Tracy D'arth said:

What if the surveyor bangs a hole in the hull? Who restores it to watertight? The seller who has no right to the survey because the buyer is paying for it or the buyer because they and their surveyor caused the damage?

 

 

I'd assume surveyors have third party liability insurance for when they break boats, hopefully more often from being slightly clumsy with an engine fitting or cratch cover than sinking them!

 

And if I was buying a boat again, I'd happily steer clear of anyone whose main worry about a surveyor was that their hull might not survive being hit by a hammer... 

[Alan de Enfield]

42 minutes ago, MtB said:

 

Thanks! So the 4th one in the about ten years you've been a boat techy? 

 

I'm just trying to get a feel for how common this is. I don't think it was ever a thing 25 years ago, but now it is. 

 

 

 

 

It is very common in the Marine environment but in the past has been less so in the Inland waterways, but, Nitrate run off from agricultural land has made it far more common.

 

One of the early reports was in 1966 when it perforated an 8mm mild steel ship in under 2 years .................

 

 

Microbial Corrosion Marine.pdf

Edited March 22, 2023 by Alan de Enfield

[MtB]

2 minutes ago, Alan de Enfield said:

 

 

It is very common in the Marine environment but in the past has bee less so in the Imland waterways, but Nitrate run off from agricultural land has made it far more common.

 

One of the earyy reports was in 1966 when it perforated an 8mm mild steel ship in under 2 years .................

 

 

Microbial Corrosion Marine.pdf 2.08 MB · 0 downloads

 

 

Thanks! 

 

Interesting to note the MIC occurred on the inside face of the bilge steel, not externally. 

[matty40s]

11 hours ago, MtB said:

 

Thanks! So the 4th one in the about ten years you've been a boat techy? 

 

I'm just trying to get a feel for how common this is. I don't think it was ever a thing 25 years ago, but now it is. 

 

 

No,that's the 4th one in the last 12 months.

[Alan de Enfield]

11 hours ago, MtB said:

 

 

Thanks! 

 

Interesting to note the MIC occurred on the inside face of the bilge steel, not externally. 

 

Which just goes to show that if you have a leaky stern gland, and you are in a nutrient rich canal , it'll get you from 'both sides'

[Lady M]

1 hour ago, matty40s said:

No,that's the 4th one in the last 12 months.

Were they all boats which had been epoxied?

[matty40s]

12 minutes ago, Lady C said:

Were they all boats which had been epoxied?

No, the other 3 were bitumen

[Alan de Enfield]

14 minutes ago, Lady C said:

Were they all boats which had been epoxied?

 

It should be a very low risk for PROPERLY grit blasted boats (as that removes any MIC) which is the norm for epoxied hulls.

 

However once the coating (any coating) is scratched / penetrated then the MIC can get in to the steel surface and it then migrates along the steel surface underneath the coating and can infect the whole hull

 

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

[matty40s]

2 minutes ago, Alan de Enfield said:

 

It should be a very low risk for PROPERLY grit blasted boats (as that removes any MIC) which is the norm for epoxied hulls.

 

However once the coating (any coating) is scratched / penetrated then the MIC can get in to the steel surface and it then migrates along the steel surface underneath the coating and can infect the whole hull

 

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

You've already copy and pasted that....

[Alan de Enfield]

Just now, matty40s said:

You've already copy and pasted that....

 

Repetition to add emphasis.

[MtB]

16 hours ago, matty40s said:

If you dont have a survey, you may well not know that your hull is rotting swiftly away underwater.

This boat came in, after apparently being 2 packed in 2019, so the owners thought it was well protected.

Nothing at all stayed on underwater, and MIC is evident all over the hull.

 

However, it was down to us to point out what it was to the surveyor, who hadnt come across it before!!!

 

So what did you do to this boat to fix it?

 

Is it a case of grit blasting and two packing again and crossed fingers it doesn't do it again in three years?

 

[AG2]

15 hours ago, Alan de Enfield said:

 

 

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.

 

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..

Thanks for the explanation I was going to ask about MIC.

Every day is a learning day.

[Peanut]

I read that you need to wash down with hyperchlorite, bleach, to kill most of the bacteria. Then rinse off, before overcoating.

[MtB]

8 minutes ago, Peanut said:

I read that you need to wash down with hyperchlorite, bleach,

 

Or more accurately, wash the boat down with said bleach ...  😅 😅 😅

[matty40s]

1 hour ago, MtB said:

 

So what did you do to this boat to fix it?

 

Is it a case of grit blasting and two packing again and crossed fingers it doesn't do it again in three years?

 

The orange rust re-appeared 24 hours after jet washing, the survey was 2 days later and it was rife.

We havnt got gritblasting facility, nor can we access the baseplate effectively, so we have wire wheeled, bleached the hull for 24 hours, washed it and will black normally. The owner is booking it into Debdale for the complete Works next year.