My Osmosis

[pcatterall]

Sorry to raise this so soon after all the other comments.

I knew that there were some blisters on my boat (she is 30 years young! ) if there had not been too many then I would have gone for the option of grinding them out, washing, drying filling then epoxying.

After exposing blisters over a few square metres I dug out a few but found no liquid at all ( I have seen and smelt the osmosis liquid on other boats) The gelcoat under the blisters was solid (no cavity)

The meter readings are fairly similar above and below the water line.
My current thinking is to epoxy the test area and monitor this for a couple of seasons.

Any ideas on blisters and no liquid or cavity
Regards

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[longjohnsilver]

You say The gelcoat under the blisters was solid (no cavity). I suspect that you could well have blisters in the antifouling. Otherwise the gel coat wouldn't be UNDER the blister, it would be the other way around, surely?

And if the hull is all dry then it's not osmosis.


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[Guest]

Read "The Fibreglass Boat Repair manual"

Author Allan Vaitses

Publisher Adlard Coles

ISBN 0-229-11855-0

Frank Marsden

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[pcatterall]

Thanks,guys for the responses.
The blisters are from the gelcoat, they are about 5mm accross and about 1 mm high. when I grind them out they appear to be solid gel coat ie no cavity as I have found on another boat.
Perhaps I need to go deeper than the 3 to 4 mm which I dug out (I hadn't got to the fibres)
Will check out the book, put it on my Christmas list!
Thanks again

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[graham]

I have exactly the same on my boat .The problem only seems to become crucial if the boat is for sale .I have never heard of a boat sinking from it.have a look at this website http://marinesurvey.com/yacht/BuyingBlisterBoat.htm

Sorry not clever enough to do a link.

Personally I will grind out blisters as they appear clean and dry then fill with epoxy filler.A proffessional repair on my boat would be about equal to its resale value .Eventually I will either sell her on cheaply or look into a DIY repair.

In my opinion the problem has been over exagerated by boatyards making lots of money .

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[oldsaltoz]

G'day Peter,

You need to grind deeper and expose the fibreglass, look for a brownish stain, it may be very small and as you grind it may change direction, so just grind a little at a time and check for the stain, when you see whitish or a larger brown stain you are close to the cavity.

Make sure you have eye protection as it may squirt out under pressure.

Andavagoodweekend.........



<hr width=100% size=1> Old Salt Oz /forums/images/icons/cool.gif Growing old is unavoidable. However, growing up is still optional.

 

[cliff]

"In my opinion the problem has been over exagerated by boatyards making lots of money . "

Praise be....... Finally a voice of reason from the gloom.

I often wonder if there was no such thing as osmosis what the buzz word would be or what folk would find to worry about?

Got a few blisters - take them out and fill the holes with epoxy after washing and drying. Why is there such a song and dance made over repairing osmotic blistering?

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[staugur]

hey don't be so flippant. We all know the over reaction from the yards-Oh my god it's rampant but we can fix it!!I used to skipper a $15,000,000 aluminium yacht built at one of the premier yards in Holland and on it's first survey for insurance purposes in Fort lauderdale the surveyor took one look at the hull and screamed OSMOSIS. He calmed down a bit when I explained it was in his terminology"aluminum" and passed us off.But is was pocked and after researching things I found it was painted outside in holland in february.Wasn't long befoer the topsides went the same route and we got it all done for free. As for glassfiber(excuse me) go ask some of the major builders in the earlier years such as sos,swan.They had terrible problems with their resins and whilts most of the water incursion was between the gel coat and the grp some hulls suffered terribly with almost unbelievable water saturation and delamination.I don't remember whats acceptable to a surveyor or insurance company but if that little meter reads above a certain percentage you are in the shit and I've seen it 3 or 4 times over.I've seen hulls with blisters under the antifouling that are perfect and I've seen them under the gell but you better make sure it's not into the glass.

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