Osmosis treatment

[andyb]

Hi eveyone,
Have just had the hull grit blasted, to remove anti fouling, the survey when I purchased the boat, reported osmosis, as you would expect in a 1964 hull.

The blasting has revealed the true extent, with the bottom very badly pitted and blistered.
I do not want to peel the gel coat, so I was wondering that if I gave the hull a coat of epoxy resin, to seal the pitting and the blisters, then filled any inperfections before painting this would remedy the problem

Thans Andy

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[Guest]

Are you serious - or is this a wind-up ?

Seal in the blisters ?????

OK - maybe grind out the blisters - wash out and dry - then fill ..... a poor substitute for real work .... but to spend out on epoxy and seal them in ??????


<hr width=100% size=1>Nigel ... and of course Yahoo groups :
http://groups.yahoo.com/group/gps-navigator/

 

[boatmike]

No Andy. You will make things worse that way. Either remove all Gel coat or grind back affected areas to substrate. Then DRY OUT (this can take some time) before recoating. When breaking through blisters be sure to wear a face mask or you will risk getting a high pressure jet of toxic chemical in your face..

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[andyb]

I did plan to grind out the blisters first, there are very few actual blisters.
The gel coat is flaky in appearance and having ground out these areas I planned to treat it then.
The boat has been out of the water since last December and is dry with no weeping from any blisters


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[boatmike]

Difficult to comment without seeing it but suggest you try using a fairly course flap wheel on an angle grinder rather than a grinding wheel and work slowly. Dont "melt" the gel coat or it will clog your wheel. For large areas the gel coat should be "peeled" Best done professionally. For small areas work carefully with an angle grinder and stop before you come to the upholstery.......
What has to be recognised is that a full professional peeling and re-coating job will probably cost more than the boats value justifies at this age. You can do a perfectly adequate job if you use common sense yourself but work slowly and make sure you have removed all of the problem before coating with Gelshield or similar. Also recognose that international recommend at least 6 coats....

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[andyb]

Thanks for you constructive an helpfull reply
Andy

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[Guest]

Final coating ...

If you grind out and fill ..... I would suggest that you do not overcoat 6 coats of epoxy .... but keep to a minimum, reason is that you can guarantee that you will have this job repeating on and off for years as it is impossible to cure with this regime. In fact it is not possible to cure absolutely 100% anyway - only control it.

If you carefully check - no-one claims to 100% seal the hull against recurrence - its impossible. What priofessional systems do ... peel/ hot-vac / dry-out / epoxy etc. is to put the best onto a dry hull to give the longest and most impermiable barrier humanly possible and practical.

Later on - you will probably end up with the peel and epoxy properly job - but you can certainly add some years before that by a careful private grind out / fill policy ........ in fact you could see many years if done with real care.

BUT the main point is - It is not a full substitute for professional work.

PS - I am not connected to any Osmosis centre or co. involved in it - other than my own independent services as surveyor.


<hr width=100% size=1>Nigel ... and of course Yahoo groups :
http://groups.yahoo.com/group/gps-navigator/

 

[silverseal]

How many boats have sunk due to osmosis?

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[andyb]

Re: Final coating ...

Thanks Nigel,
thats the main idea, if I can get a few years out of her then I will be happyas I paid 7K for her and a full blown peel and epoxy would not be cost effective.
Any good suppliers on the south coast for the epoxy?

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[Guest]

Re: Final coating ...

You can go direct to Blakes or International ...... BUT - you may find that prices are discounted via some chandlers .....

I am not suggesting this so only remark on this as what I have seen ..... some boats have been ground out blisters, filled, fine-filled to give nice final surface ..... then given a good coat of anti-foul primer particular if you can get an epoxy one. Another is VC-Tar primer and top anti-foul ...... Why - the answer given tome was why spend out on expensive epoxy Gel-shield etc., if later down the road I have to grind some more etc. The primer / VC-tar give a sort of barrier that slows it down .... I will not say I agree - but I cannot disagree completely ....

You also have to remember that it is not unknown for epoxy coat to interfere with Moisture Meter readings .....

The choice finally is always yours and I wish all the best.


<hr width=100% size=1>Nigel ... and of course Yahoo groups :
http://groups.yahoo.com/group/gps-navigator/

 

[Mollari]

Having a 36 year old boat, I have a few blisters myself. I investigated the various opinions of hull peels and other treatments.

I then stumbled onto a book called Fibreglass boats by Hugo du Plessis. Read it thoroughly before you prematurely sentance your boat to the death by peeling.

Due to the age of your boat some blisters may be due to the moulding of the hull as boat manufacturers did not have the tech they do today and may have given you a very thick gel-coat on to of a very thick hull, the styrene vapours mix with the water drawn in through the gelcoat by osmatic action, hence the blister, are the blisters acidic, alkali, or do they smell of resin.

Sadly there are a number of surveyors who condem a boat to the peeler when gradual monitoring and maintenance are all that is needed.

by the book, read it then decide.

For example a moonraker was given the epoxy treatment after an unrequired peel, 4 years later his epoxy coat has all but fallen off. The boat was surveyed by a very well known surveyor and the treatment was done by a very well known company.

Osmosis is the process in which the hull draws water though it. For example when a drug addict takes ecstacy it is Osmosis that draws water from the body into the brain, and kills them. No way would they want to peel a skull /forums/images/icons/smile.gif

All joking aside, get the book and read it. (no I am not on commision, but it has saved me a fortune)

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[Scarron]

Hi Andy,

I am in a similar position with my 1969 Triana, the surveyor found a few small blisters and his recommendation was to sand and fill them and overcoat with epoxy [ it has already been epoxied in the past tho.]

However I have spoken to two very knowledgable people on the trade and they both said that even tho' it has been out of the water for three years it still won't be dry - you do have to remove the gel and allow it to dry over time. Also that its probably not worth doing much other than a few coats of epoxy and anti foul. Gel peeling is approx £500 and may be a rocky road as suggested by others on here.

I reckon I might do the minimum to mine, after all - it might be a little heavier but so what, it was built to Lloyds A1 by Tylers so it weighs a ton, well four actually and it definately won't be sinking due to Osmosis any time soon.

What they also suggested was not to buy marine epoxy, apparently if your on a budget a good quality industrial epoxy floor paint is a very acceptable alternative, probably identical in fact! We've just painted some floors at work and the stuff we been using for a while now is virtually indestructible and even better its only £28.50 + VAT for 5 litres. [try www.regalpaints.co.uk] Someone else recommended an industrial epoxy called Sigma [www.sigmacoatings.com] used for painting oil rigs apparently.

Hope this is useful - for what its worth and having done a lot of research a significant consensus considers the whole osmosis thing to be somewhat overblown.

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[Mollari]

Too true again.

It has been overblown, I have used Sigma is Mossel bay on an Oil rig, It worked for that, I should have remembered that. Thanks for reminding me.

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[boatmike]

Re: Final coating ...

If you are indeed a surveyor you should know that less than 6 coats of epoxy will not do the job properly. If the chap already has osmotic blisters you should know that removing the gel coat leaves an already suspect substrate structure even more exposed needing the protection of Gelshield or something similar even more than a new vessel would. Why NOT give it maximum protection? Under these circumstances it would be foolhardy to skimp on the manufacturers recommendations. By all means put VC Tar or any other product over the top but dont skimp on the protective coat of epoxy or all the work will be for nothing. It is true that there are no guarantees that in time the problem will not occur but all he is trying to do is get a few more years of useful life out of an old hull at lowest cost. What is the cost in time or money of adding extra coats of epoxy? The time and effort is (or should be) in the preparation. Personally I would give it more not less.

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[Guest]

Re: Final coating ... reply to Boatmike

I did not advise to do as you are implying I did ..... I passed on an observation of what others have done. Second the owner is already saying that he will not conduct fuill osmosis treatment - which recc'ds the 6 coats are based on ....

I do not condem them for what they did - in fact I can see their point in not spending out and time on Gelshielding etc.

As a Surveyor I would of course in my duty to a client advise best route and then its up to them to decide. I would not actually get involved professionally in a Grind and fill policy - as that is against professional reccomendations - the real way to do the job is to get it done properly and final.

My reason for passing it on is to illustrate the different attitudes of owners and their remedy's /actions - if you cannot accept that - then I am sorry - I shall not change for you.

The point about covering up an incomplete job - which in all fairness is what this is ... is valid, but brings other factors into play. The epoxy wil effectively be sealing in a problem and not as you say ..... Why ? because the remianing strata is already suspect. It doesn't need any more to create it. Also the fller used can be epoxy based and in itself seal the points that are ground out and flushed - allowing the rest of the hull to be treated later without wasting large amounts of cash on possibly wasteful application.
Why mention VC Tar / epoxy based a/f primers etc. - that is what others I have seen use and I have to admit that I have seen no real adverse effects of the policy - as some years later - in what appears similar time frame as those who thought to go a more expensive route - have had to grind and fill other areas as well.

It is remembered that a while ago on possibly this forum - a guy complained that he had spent hours grinding / filling etc. and then a few year later had to re-do all again .... and I remermber that he had epoxied etc as well to recc'd levels etc.

You also have to remember that application of epoxy can seriously upset any metering of the hull later and underlying problems can be missed or even exaggerated ....

Sorry but my stand is to get it done professionally at a suitable time. Any interim actions should not interfere or cause error in later judgement / solution to the problem - but hopefull delay the inevitable treatment that will be required. The interim actions should also not delude the owner into thinkiing that he has cured the problem - which I am sorry - your post may do .....

If the original postee can extend his sailing by another 5 years - which is not unreasonable - that gives him 5 years to sort out where, how and what cost etc. to do a proper job.

Finally - 6 coats of GelShield is recc'd by Manufacturer based on the job being done properly - not grind and fill actions. In properly - I mean either before water touches hull or after peeling / blasting etc and drying out. It would be intersting if you contacted the manufacturers and asked them for their recc'd after only spot grind and fill ..... I hink the answer would be a lot different .......

I take it you have no objection to me having personal views .....


<hr width=100% size=1>Nigel ... and of course Yahoo groups :
http://groups.yahoo.com/group/gps-navigator/

 

[Guest]

So there we are a good range of answers ...

I have now been remionded of epoxy from commercial work .... the Sigma I should have remembered from my Tanker days ....

Peeling / treatment - your choice - many havent, many have.

Grind and fill - can be a delaying tactic that can give you some reasonable extra years .... (not that osmosis actually stops a boat from sailing anyway)

A good read through, check out some books .... be careful though - there are books out there by some very well known names that are just plain garbage when it comes to this .... sadly I cannot name for legal reasons as you can imagine.

Me my boat has heavy 'wet' hull - do I treat it .... no. I'm a surveyor yes .... but doesn't change that I also look at cost vs risk / boat value etc.

Good luck and let usall know what you do. Don't be scared off by the scare-mongers ....


<hr width=100% size=1>Nigel ... and of course Yahoo groups :
http://groups.yahoo.com/group/gps-navigator/

 

[boatmike]

Re: Final coating ... reply to Boatmike

I believe you have missed that this guy has an old boat on a low budget. This boat, like many like it will NEVER get a full gel coat peel and professional re-coat as it would not be cost effective. The best he can do is grind out the problem as he sees it and replace the gel coat removed with epoxy. How long a life this will give the boat will depend on how good a job he does. The majority of time and effort will go in to preparation. The cost of giving it 6 full coats of Gelshield or something similar is small. It's only a small boat anyway. The cost of launching without a proper coating will be that all that work will be wasted. He will have exposed the CSM layer by removing the gel coat and not replaced it with an effective protection which could actually make matters worse than they are now.
Yes I have no problem with you having an opinion of course! That's what this forum is for. Do you have a problem with me saying I disagree with you?

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[celandine]

In skilled hands and the right settings, a grit-blaster can be made to remove most of the thickness of the gelcoat, whilst litterally blasting open all the blisters. It might be worth finding out if whoever did the anti-foul removal has the ability to do this. It will produce a more thorough job than grinding ever will, and will save you a heck of a lot of time. You will then need to leave the boat out of the water for as long as you can stand it. (The optimum length of time is too depressing to contemplate) and she will require periodic pressure washing. Once dry, the subsequent filling, faring and coating is not really skilled work - just long and boring. Good luck with it.

Mick

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[Guest]

Blimey ... we agree on something !

I was posting in terms of his limited budget / older boat / not doing a full peel and epoxy job - that is precisely my point ....

I have no problem whatsoever with opinions or views etc. - but you satrted with the ...... If you are a Surveyor stand - what am I supposed to do with that ?

I am saying that the grind and fill tactic - which I have used nyself when I considered that full remedy could be put off till later - is NOT a real remedy - it is a delaying tactic. I was also saying that the cost of full blown epoxy treatment is money wasted in this and similar cases - as the hull is not dried out not opened up sufficiently to do a full epoxy job.

I certainly would NEVER advocate unsealed CSM or hull lay-up be exposed to launching - other than when a boat is transferred to a treatment place after blasting / peeling ..... which IS possible .... If you read properly - I mentioned epoxy fillers and agreed that a barrier of some description be applied - it now so happens that I have been reminded about tank coatings ... one name of which is Sigma .... which is cheap and effective.

Are you seriously suggesting that full blown re-coat of a hull that has not been treated properly shouild be done ? The cost and time involved in that route with such as GelShield etc. is debatable. Are you suggesting that the re-coat after grind and fill will be enough ????

My honest opinion and I repeat this is not what I should advise professionally - but is what I would do on my boat ..... grind out and fill with epoxy filler. Fine fill surface to be able to sand back smooth ..... give it then a patch coat of epoxy ... but certainly would think very seriously before coating all the hull.

We are actually not far apart on the subject - the difference lies in this insistence by you of the 6 coats on the untreated hull that I have a differing opinion on.

So ?

<hr width=100% size=1>Nigel ... and of course Yahoo groups :
http://groups.yahoo.com/group/gps-navigator/

 

[boatmike]

Re: Blimey ... we agree on something !

I would rather not argue with you. You were the one trading on your credentials not I. Lets just stop arguing in public shall we? It's not what this forum is for and if I have offended you I am sorry. I started by trying to answer the original question rather than ridicule it as a wind up as you did. The poor chap needs advice. We have both now given it and he can choose from all the advice given as he sees fit. OK? Enough!

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