Survey Epoxied Hull

[jonjo]

> Basically most surveyors will not check moisture to determine the condition
> of a hull that shows no blistering. Its pointless.

Why do 90% of GRP yacht survey reports quote moisture levels and then discuss the implications?

> Indeed if an average boat is left out during the summer months (even in
> the UK!) it will become very dry indeed

In the osmosis treatment business it is well known that thick laminates, as found on Nicholson’s for example, can take longer than 6 months to air dry even with the gel coat peeled off.

You paint a picture of a GRP hull soaking up water and then venting off moisture on an annual cycle like a sponge. The picture you paint flies in the face of perceived wisdom on this subject.

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[boatmike]

And the picture YOU paint is that of someone who just loves an argument for its own sake. Do you never give up?

Nevertheless I contacted a surveyor friend of mine to get his independant views and I repeat them here almost as he told it to me for the sake of clarity.

"In recent years it has become necessary for surveyors to include a moisture reading of the hull in a report regardless of the need for one as it has become an expected part of the report. In the majority of cases the client has no idea what the significance of the readings are so we have to write a paragraph to tell them what the readings mean. In the majority of cases on older vessels, especially if the vessel has been in the water for more than 3 years without a winter layup ashore (which is becoming increasingly found to be the case with marina berthed vessels), the reading will be understandably high. In such cases it is often difficult to convince the client that this is normal and nothing to worry about unless accompanied by blistering, damage, or other defects in the laminate as a winter layup ashore will usually mean a considerably reduced reading if taken again in the spring."
When asked why it has become almost standard practice, he reiterated that if one surveyor does it then there is a false impression given that if another doesn't that survey must be inferior. It is not done because a high reading shows the boat is in poor condition. Conversely a low reading does not necessarily indicate a good condition.

I therefore am out of date perhaps in suggesting that surveyors don't do moisture readings unless deemed necessary. They all now seem to have their own meters and use them at most surveys as it makes their survey look more professional and costs almost nothing to do. The fact that we have a small army of surveyors providing meaningless numbers to ignorant clients does not alter the facts. Polyester resin reinforced with chop strand matt IS a bit like a sponge frankly. The amount of water taken up by a composite hull is of a considerably lower order than that of a wooden hull but they DO absorb moisture. THATS WHY INTELLIGENT PURCHASERS OF NEW VESSELS PROTECT THEIR INVESTMENT BY EPOXY COATING.
I also asked my surveyor friend what he would do if he saw a hull in good general condition with a properly applied coat of epoxy. His reply was. Leave well alone!
Can you now please stop arguing. I don't really care if you decide to believe in something else and this is, I promise my last word on this subject even if you think I am talking complete rubbish. You appear to be correct in that many surveyors report on moisture contents. I would venture that they are driven to it by people like you who are not willing to be convinced by the opinion of a qualified person without pages of pseudo-scientific bullshit that they don't understand anyway.

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[Ships_Cat]

jonjo I think that maybe you are taking stances outside of your depth in which case you are likely to drown.

Re your <<<But in general if made an offer on an epoxy coated yacht and the owner then reacted as strongly as you to the suggestion of removing some test patches I would walk away from the deal.>>>

You are perfectly entitled to do that but in doing so you may eliminate the possibility of buying a good boat. If the owner does not want the coatings damaged then the boat is quite possibly one that has been cared for. If I was the seller I would probably be glad that you did walk away because of the likelihood of downstream erroneous complaints from an unknowledgable purchaser.

My own boat is metal and while coatings are easily repaired on that I would not let anyone breach them for the sake of inspection as invariably a weak point will result.

Re your <<<You paint a picture of a GRP hull soaking up water and then venting off moisture on an annual cycle like a sponge. The picture you paint flies in the face of perceived wisdom on this subject.>>>

Mike is correct on this. Osmotic pressure will drive water into GRP and into many other plastic structures and coatings including even epoxy ones and gel coat. Not generally understood along a similar line is that on metal boats with underwater epoxy coatings the water will drive through to the hull over time and that can be to the extent that problems can be encountered with zinc based primers on steel boats, for example (many paint systems now avoid zinc based primers). The coating will dry out if removed from the water.

A GRP boat will take up water into its structure when in the sea and then give it up when on the hard so does in fact act just like a sponge. Blistering is not because the hull is wet and wetness cannot be used as an indicator of pox, unless it is severe in which case the blistering will be obvious. The hull will then also give the appearance of not drying because the "moisture" being measured is in fact the hydolysed resin. Blistering is caused by inferior materials and application resulting in resin hydrolysing with the water that is present in all immersed hulls.

John


<hr width=100% size=1>I am the cat but I am only 6.

 

[Ships_Cat]

Not going to play snap with you /forums/images/icons/smile.gif. We must of hit the send button at the same time.

John

<hr width=100% size=1>I am the cat but I am only 6.

 

[boatmike]

Well John. He has had the same unsolicited reply now from both hemispheres! We will probably be accused of collosion now I suppose. Oh well.. "There are none so blind as they who will not see" I'm going to bed now. Theres now't on telly worth watching anyway otherwise I would not be sitting in front of this bloody computer in the first place...

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[jonjo]

John can I first say thank you for posting a challenging but reasonably presented response. Have to say I have been getting fed up with dealing with prickly maritime professionals who believe their postings are above rational analysis and question. www.ybw.com is going down hill and I am questioning my continued presence here, the level of debate and civility is looking higher on sailing newsgroups at times which is a sad comment on this place.

> You are perfectly entitled to do that but in doing so you may eliminate
> the possibility of buying a good boat

I recall an interview with Lord Hanson. When questioned about his secret of financial success he said that, faced with a deal he asks what can he loose not what can he gain. The epoxy layer might cover various problems, that is why I would walk away.

> A GRP boat will take up water into its structure when in the sea and
> then give it up when on the hard so does in fact act just like a sponge

I am with you all the way about the osmotic forces at play driving water into the hull but I think an outsider reading this thread would get the impression that after two years afloat a GRP hull has sponged up its natural water capacity at which point osmotic equilibrium is reached unless inferior materials drive the process further to create blisters.

From everything I have read, water ingress into GRP is a much slower process that develops over 10 to 20 years.

The problem I have is with the opinion that a summer in a cradle dries out a GRP hull. What force is at play that can reverse the osmotic process? If osmosis attracted the water into the GRP laminate in the first place it will now be in solution with something more salty than sea water, so can dry air now entice the water out through the gel coat?

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[jonjo]

> And the picture YOU paint is that of someone who just loves an argument
> for its own sake.

If that was the case I would revel in the fox hunting type debates here at YBW.com. I actually steer clear of these.

Final word to the original poster if he is still with us.

Osmotic blisters are for real and when the pox strikes the corrective action amounts to 10% to 20% of the value of a mid range second hand yacht.

Raised levels of hull moisture almost invariably precede osmotic blisters but B does not always follow A.

Most buyers want to know about hull moisture levels when buying a yacht and surveyors routinely provide this information.

When removing a test patch of epoxy coating your surveyor will be able to judge something about the quality of the coat through counting mixed colour layers and the adherence to the hull.

After removing the coating he may then spot the real DIY horror stories such as epoxy covering a wet hull or as I saw last year, the repairs following a gel peel botch up with an angle grinder.

At any point in the last 25 years the marine industry was convinced that the osmosis issue was understood, addressed and the implications scoped.

And anyhow it is all the fault of quisling surveyors, stupid people like me, boat owners, boat buyers, the 1973 oil price hike or osmosis repair shops.

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[Ships_Cat]

<<<If osmosis attracted the water into the GRP laminate in the first place it will now be in solution with something more salty than sea water, so can dry air now entice the water out through the gel coat?>>>

I am no GRP expert but the following is my understanding from working in the marine industry but mainly with metal boats (but whose coatings also take up water).

I think that part of the trouble is the loose use of the word osmosis in that it is in common usage (including by me) to describe the illness and further say the mechanism with which water enters the structure is osmotic. However, it is actually absorbtion through which the water enters. There are other mechanisms by which it is claimed that water transports through the laminate such as by wicking. Maybe there is some truth in the use of the name as one assumes that as the structure dampens right through then evaporation on the bilge side will create a pressure difference which encourages more absorption on the water side but I assume that was not in peoples' minds when the term was coined.

Whether osmosis is actually involved in the formation of voids and blisters themselves through water entry I do not know but the main mechanism in them is one of hydrolysis of the resin and the result is claimed to be corrosive resulting in a localised breakdown of the structure.

So, from the point of view of absorbtion and mechanisms such as wicking we know from common experience that when water enters materials by those the process is reversible by placing the material in a drier atmosphere. I do not see any reason why that is not so with grp. From my understanding the grp, like most other things, dries quite quickly in suitable conditions (dry atmosphere, sun, wind) and the moisture level drops.

But as I said in the other post the moisture level will only drop to the level of that which is hydrolysed with the resin (the illness described as "osmosis", "pox" or whatever). My understanding is that the water so involved does not come out through normal drying and I think it is that which you are referring to in the quote above.

However, behind all that, grp does absorb water, but I do not know how long it continues to do so before becoming saturated. Probably like many things the initial take up is comparatively rapid but quite a long time to reach saturation as the wetter most materials become the rate of absorption slows down (assuming that the environment stays the same). At anytime though the absorbed water can be dried out of it, like a sponge, except for that mentioned above hydrolysed with the resin in the voids.

John

<hr width=100% size=1>I am the cat but I am only 6.

 

[jonjo]

Thank you this has moved my understanding of the subject forward.

I am getting a picture of water entering a GRP hull on two distinct missions.

One is driven by osmosis and is a one-way trip after which the water becomes locked in at a molecular level. There is a high chance this type of water ingress will lead to osmotic blisters.

The other, which accounts for a larger % of measured hull moisture, is an as yet unidentified absorption process which is reversible with simple drying. Water that enters a GRP laminate through this process can co-exist with the rest of the hull material without causing damage.

Well this is plausible and would explain diverse observations about moisture level and the development of osmotic blisters in the real world. I suspect things are not as binary as the theory indicates and that the higher the level of non reacted water then the greater chance this will encourage damaging osmosis.

I will be interested to see how this interpretation pans out but I would still want to see moisture level readings in a yacht survey report before writing a number with lots of zeros in a cheque book.

Trouble with the whole subject is the range of interpretations among professionals and the fact that individual boat owners can quote personal experiences that confirm and contract any theory in circulation.

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[cliff]

Re: Best price

Sorry - I am talking generalities - I used you as an example as you seem to think you or your surveyor has the right to vandalise a third persons boat. Neither you nor anyone else has the right to structurally or cosmetically damage any vessel in the pursuit of a survey.

And in answer to your questions
yes, I have a vessel for sale.
No, you have not contacted me.
No, you have not shown any interest in purchasing my boat.
My "protective instincts" over my hull are nothing to do with osmosis treatment, they are purely mercenary - who is going to pay for making good such damage damage?.

As for your final remark, it is your right to walk away from any such purchase as it is the sellers right to protect HIS boat.

Personally I would not have a problem if any prospective buyer ASKED if he could have a reasonable number of patches of epoxy/ gel-shield removed provided he paid the yard for removing them, storage of the boat while the repairs were made, paid the yard for making the repairs and paid for the relaunch irrespective of whether or not he purchased the boat.

I already have had several items stolen from my boat by perspective purchasers not to mention the teleflex "red button" being snapped off, engine bay light left on (and batteries left on) on two occasions resulting in flat batteries, gas left on both at cylinder and stop valve beside cooker. One comedian went to start the engine by pressing the "red button" on the throttle and opening the throttle FULL before turning the key. YES I want MY engine started on full throttle so it can go from zero to peak revs in a second or less - I think not. When stopped he said "someone told him that was how to start an engine" After I explained to him that the engine was started in neutral and throttle closed he cranks her over without any preheat - knocked 7 bells out of the batteries but she did start. I had to remind him to check the coolant discharge "er, um, what?" says he. There was no water as the intake valve was shut!

Now, you might say I am over protective of my boat but she is mine for the moment and I do not see why I should allow her to be damaged in any way by anyone.

It is a sad day when one has to say "accompanied viewing only", disconnect the batteries and remove everything that is not nailed (or epoxied) down.

I always assumed that the boaty fraternity respected others property whether it was a little sailing dingy, a 30 footer or a mega yacht but I guess I was wrong - It is obvious to me that some have no respect for others property.

Finally jonjo, I trust you find someone who would let you (or your appointed surveyor) take a grinder to their epoxy, but in IMHO I think you will wind up doing a lot of walking away. I certainly would not allow it on any boat of mine unless the prospective buyer agreed to pay all costs and make good the damage.

Point of interest - some folk have their hulls epoxied as a preventative measure not a cure for osmosis although I have never heard of a boat sinking because of osmosis.

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[billskip]

hi mike
ive read with intrest this thread and feel that a good disscussion can be very healthy and infornative..brings out the best in people and also goes into more depth..however...if a hull soaks up salt water then dries out ..what happens to the salt? is it left behind in the hull ? sorry for any spell mistakes..my pc is dyslexic..

<hr width=100% size=1>Bill

 

[boatmike]

Interesting question actually. I have to say I don't know the answer definitively but I can say that I have never detected any chrystalline deposits that could be salt when conducting repairs unless they were in a surface blister, in which case I would have ground them out.
What I "think" is that with such osmotic water take up the hull probably acts as a filter to a large extent and may well filter out the salt. After all this is what happens in reverse with reverse-osmosis desalination filters isn't it? In which case there would certainly be a reduced salt content in the water that gets into the structure if any at all... That's only a theory though and I always try to say when I don't know..... Does anyone else?

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[andy_wilson]

Surveys are normally non-distructive inspections.

Anti-foul is classed as a consumable but not an epoxy coating, which would require 5 or more applications to replace.

The surveyor would still scrape anti-fouling and look for signs of an intact epoxy coat, and signs of blistering, and report accordingly.

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[billskip]

intresting about the salt mike..i think salt is filtered out as you say..except where the blister has leaked while hull in the water and allowed the salt to get in..i know there are a lot of people that are experts in glass boat building and know all about osmosis..but i believe that a high percentage of osmosis is caused by moisture getting into the glass from the inside and when the moisture finds its way to the gellcoat (inside)it cant get out so it builds up and starts to react...i think that many boats are not kept dry on the inside and moisture will find its way into the glass because the "finnish" on the inside is very poor in places and often you get tufft ends of fiber unsealed about the bulkheads...just my own thoughts..maybe all this "ripping off the gellcoat and epoxy coating" on the outside may be better to repair the blisters and seal the inside..

<hr width=100% size=1>Bill