The best way to ignore Osmosis...?

M

matnoo

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First of all my boat was a freebee. It was so knackered when I got it that my uncle said 'if you can be arsed to fix it you can have it!'

And so I have a small 1960s fibreglass transatlantic yacht. It most definatley has Osmosis. Many 5p to 50p sized bubbles which stand proud around 1 to 2mm. The hull is 6mm thick on deck so I am pretty sure the hull will be thicker and is not going to sink because of these bubbles! I simply do not have the time or money anymore to fix it to as good as new. Ive had enough of boat fixing for one lifetime!

I am resolved to leaving them, so my question is what is the best way to live with osmosis? So far its been stripped back to a rainbow hull and very few of the bubbles are burstable.

Should I
1. Leave the bubbles, Gel coat, undercoat and antifoul
2 burst the bubbles gel coat undercoat and antifoul
3. Just antifoul the damn thing (thats what id like to do)

Will a gel coat stop the bubbles getting any bigger?

Mat
 
Most advice seems to be that putting gel coat on top of the blisters will seal the water in, which ultimately may make the situation worse. Full treatment requires grinding or peeling back and drying for a long time, effectively putting an end to sailing for 2008. In your situation I would do nothing other than apply antifouling and keep an eye on the blisters.
 
The comment that very few will burst is a little strange. With osmosis the point of a knive will normally pop any of the blisters and the liquid that comes out has a very distinctive smell if it is osmosis. I would investigate a bit more in a limited area and perhaps consider grinding out the blisters and filling with epoxy filler before antifouling. Don't bother with a gelcoat unless the go the whole way of peeling, drying and epoxy coating the whole hull.

Yoda
 
3. Just antifoul the damn thing (thats what id like to do)

Will a gel coat stop the bubbles getting any bigger?
**************************************************

ANy process to improve is time consuming and you no doubt would like to go sailing this season so why not just antifoulf and sail away while you consider and plan the future...

The action going on under the blisters will continue wether you apply gelcoat ...gelshield.....or best hombrew antiosmotic gunge!!!!1

Some folk would say go the shaving process where you decimate the hull with an oversized planer and then apply varios mixtures of epoxy and fillers to restore the shape.

This makes you feel good cos you know you got rid of all the osmosis but if not well done then you may also lose an awful lot of hull strength where the planer reached fresh air on the inside of the hull...


The american budget solution can be perfectly satisfactory.

They would recomend you countersink each blister and I have read of some owners dealing with thousands!!!! and then allowing the hull to as they say dry out. This so called drying out is not getting rid of trapped water but the products of osmosis that will give a distinct vinegar smell as soon as you burst the first blister. This drying out process is accelerated by spraying the affected areas with hot water at least once a day if possible. A large garden sprayer is perfect when filled with hot tap water..

The washing drying continues till no more vinegar smell is present and could take several months. Once all blisters are removed,countersunk and wash/dried then get a suitable International or West epoxy filler and restore the hull surface.

Prepare the whole hull and give it a few coats of Gelshield followed by your favourite shade of antifoul.

Just remember that the first coat of antifoul should be applied to the Gelshield before it is fully hardened or the antifoul wont take.

This wont restore the hull to a perfect state but it will look better and who knows it could be 15 years before the blisters dare show themselves again.

Just be aware that you need to arrange this process to give as much time as possible for the drying. If you do not spray the hull the drying gets arrested as a layer encrusts the surface until washed off.
 
[ QUOTE ]
No boat has ever sunk due to osmosis !

[/ QUOTE ]
I have the same feeling, but is it true?
Or maybe it is true because people actually do something about it...
 
So find me evidence of a boat that has sunk due to osmosis - I have seen loads of boats hacked to within inches of distruction with peelers and blasted with grit all for no reason because the osmosis will probably come back 5 years later anyway.
Buy an old heavy lay up and ignore it - only my opinion -spend thousands of pounds if it makes you feel better
 
[ QUOTE ]
So find me evidence of a boat that has sunk due to osmosis - I have seen loads of boats hacked to within inches of distruction with peelers and blasted with grit all for no reason because the osmosis will probably come back 5 years later anyway.
Buy an old heavy lay up and ignore it - only my opinion -spend thousands of pounds if it makes you feel better

[/ QUOTE ]
No, no, you don't understand, I strongly believe the same and this is my opinion when the discussion leads there. But are there any surveys,statistics or other facts that would back-up this feeling? My main argument is "I never heard of a boat sunk due to osmosis" but is it enough?
 
A good movie quote, I think it was John Candy "there is not a problem in the world that you can't ignore if you try hard enough".
Have a season, see how much you like it, then decide how much to spend
 
I'd like to think that no boat has ever sunk from osmosis too! I don't want to worry you, but, some years ago I was crawling around the Norfolk Broads and got chatting with the crew of the Conservancy launch. I was admiring a particularly smart looking large motor cruiser nearby which was for sale. The officer assured me that it was not worth considering as a survey had discovered severe osmosis, and the vessel was actually de-laminating under water and in some places the hull could be moved by hand!. So, presumably, it could have folded in the middle and gone down. All you need to know is here - http://www.aegisyachts.co.uk/osmosis.html
 
Use for the summer. Haul out and grind out all blisters. LEave to dry all winter. Rinse out blisters in the spring and fill and fair with epoxy filler. Antifoul and use. Repeat as necessary until you sell the boat!
 
Osmosis can damage the laminate and therefore could ultimately lead to sinking but in most cases it doesn't get anywhere near that. If your blisters don't burst it is possible the cause is something else altogether.
I'm with the majority here, antifoul and go sailing. Try and do anything serious about the problem and you'll lose the whole season.
It might be worth taking some close up photos of several areas underwater and carefully noting exactly where they are. At the end of the season you can compare the same areas with the photos to see if the blisters have increased in size or number.
 
Sailed my boat last season with osmosis. It is not likely to get any worse over one season. Speaking from experience, get an expert to diagnose that it is osmosis in the first place. The blisters should be fairly easy to break and will contain a brownish liquid that smells distictly of vinegar (styrene?). Even then, check that you do not have blisters from an earlier preventative epoxy treatment, not under the original gelcoat. A good indicator will be a wet hull reading on a moisture meter. If your boat is more cheap and cheerful and not too big then nothing lost next winter by grinding out the blisters, allowing them to dry etc as PCUK says. Just remember, blisters could be in just the antifoul or some underwater paint system applied back in the dark ages!!
 
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