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Frogwatch 05-25-2013 01:56 AM

Blisters, OMG
Just read the stupidest article in BOAT US magazine about hull blisters saying you should immediately repair osmotic hull blisters. BS, almost all "repairs" make things worse and the effect of blisters on performance is so small you'll never notice it There is not ONE documented case of normal osmotic blistering leading to any hull failures. It is nothing more'n a way to sell expensive "repairs" that do nothing. I know, I been there'n and done that and wasted the money.
My advice, ignore em and put on new bottom paint and go sailing secure in the knowledge that anything you do will make it worse and achieve nothing. My 1981 S2 has gazillions of blisters that do not affect her at all.

SchockT 05-25-2013 03:33 AM

Re: Blisters, OMG
Well, if you race, or at all care about sailing performance then you DON'T want a gazillion blisters. If it were my boat I would repair them if for no other reason than resale value. If you are selling your boat, and the hull looks like it has the pox, people WILL walk away, or at least want a big discount. As for the idea that repairs make it worse, I disagree again. Poor repairs could make it worse, but that goes for just about anything. If blisters are repaired properly they never come back. I repaired a lot of blisters on my Hotfoot years ago. I got some expert advice, repaired them correctly, and then I never saw another blister.

I don't know about hull failures, but a boat that is covered in blisters rather than just spots here and there has a problem, and that problem should be addressed.

jameswilson29 05-25-2013 05:19 AM

Re: Blisters, OMG
I read the article, too. I believe it was written by Don Casey, who is not too concerned about osmotic blistering. He advocates a small scale approach of pop, grind and fill each time you haul. That seems reasonable to me.

I agree with you. Too many folks get overly concerned about osmotic blistering, to the point of paying for expensive repairs and/or selling their boats. There is a whole industry out there preying on the gullible.

KeelHaulin 05-25-2013 04:23 PM

Re: Blisters, OMG
Blisters occur in the strand-mat layer which is a cosmetic layer above the cloth layer of fiberglass. I would only be concerned with blistering if the below waterline hull is balsa or open-cell foam cored. Having said this; I did do a blister job on my boat when I purchased it; at the time thinking preventative maintenance of them was the proper thing to do.

After getting the hull stripped down to gelcoat I found even more blisters that were not visible beneath the paint; as well as many poorly repaired blisters. Fixing all of them was a chore. I did it following the procedures given by MAAS epoxies. Go to their website; learn how to mix epoxy with fillers and do it yourself if you want it to be done right. All you need for tools is an angle grinder to remove the blister and a good sander after you fill them.

If you sand down to gelcoat I also recommend painting the entire hull with several layers of epoxy to prevent blistering in the future. My boat was in the water for 6 years after barrier coating with 5 coats of epoxy, 1 coat of Pettit barrier coat to tie to the bottom paint. No blisters after hauling again.

I found some blisters on the rudder; but I think the surveyor was a little too aggressive with the hammer because you could see a visible pattern of them. Which makes me wonder if hull blisters on many boats could be a result of one or multiple hull surveys :rolleyes:

deniseO30 05-25-2013 06:45 PM

Re: Blisters, OMG
No OMG here since we did the barrier coat on my boat over 3 yrs ago. :) She had a mess of waterline "pimples" and a few dozen blisters below the WL that were dry when I broke them out.

arvicola-amphibius 05-25-2013 08:05 PM

Re: Blisters, OMG
My boat just had her 50th birthday. No sign of osmosis in the hull, but a few small blisters are in the fiberglass that encapsulates the keel. They can stay there.

My sister has a fiberglass swimming pool which is now about 40 years old. Because where she lives it never freezes, the pool never gets drained in winter, so has never dried out or been treated in any way. It has had two or three quite large blisters in it for as long as I can remember, but they have not got worse over the years.

I favor doing nothing unless delamination is occurring.

SloopJonB 05-25-2013 11:48 PM

Re: Blisters, OMG
I've never had one but if I found some when hauling for bottom paint I'd spot repair them, just like I would a cracked keel fairing or a grounding ding in the keel. In my view, that's what haulout is for, not just to slap on a new coat of paint.

Way too much is made of blisters - in nearly all cases they are a minor, easily correctable flaw.

KeelHaulin 05-26-2013 03:00 AM

Re: Blisters, OMG

Originally Posted by Frogwatch (Post 1035288)
My 1981 S2 has gazillions of blisters that do not affect her at all.

If it's a balsa cored hull model (as many S2's were) I'd be checking more closely for wet core than carrying the assumption that the blisters don't affect the hull of your particular boat. If the boat is non-cored you are OK but if it's cored I would suggest stripping it down, fairing the blisters (or re-glassing the strand mat with a layer of cloth) and then barrier coating with epoxy.

Frogwatch 05-27-2013 11:11 PM

Re: Blisters, OMG
The entire concept of racing sailboats eludes me so whatever a racer thinks makes his boat go faster is fine with me. However, for us cruisers, even with blisters the size of watermelons I think my boat could be made to sail better than I am able to sail her so I don't worry about many small ones affecting her cruising performance.
My boat is very old and looks like crap but works great. OK, I have very low standards of comfort and my entire reason for going sailing is cuz I like to solve unexpected problems but I've managed to cruise a lot with a poxed boat.
So yer boat has blisters. Slap a coat of bottom paint on, shrug your shoulders and put her back in the water where you can't see em, problem solved.

KeelHaulin 05-28-2013 01:24 AM

Re: Blisters, OMG
All of that is fine; but as I said before if the hull has balsa or open cell foam and some of the blisters wick water through the skin layer of cloth you could end up with a hull that is not structurally sound. It makes little difference to me if a boat has blisters (in a solid glass hull) or the topsides are not polished; to each their own. The important part is the structural components and if those are failing or in danger of failing the underlying problem should be addressed otherwise the boat is not very seaworthy.

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