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Old 14-05-2017, 18:56   #1
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Blisters in barrier coat.

I pulled the boat after several years and as I was scraping the barnacles I started to notice small blisters.....

The boat was epoxy barrier coated in 2008 and has been in the water until this march, in Florida. There were a few hundred blisters about 1/4 inch. I sanded each one and they went into the gel coat but never penetrated into the laminate.

I call them barrier coat blisters. They were sanded out and filled with West System epoxy. I used just the resin and then came back with a resin and micro balloon filler. I sanded the spots and the thickness is very thin.

Now the bottom has a lot of spots but is otherwise ready for paint. I am wondering what to, do if anything.

-----A little more history: The boat is a 1974 Tartan 34. It never had a blister as far as I know. I have owned it for 20 years. The bottom was
"washed out" and was peeled and re laminated with vinylester in 2001. Gel coat was applied over the new laminate and anti fouling over that. The boat was in the water, in South Florida until 2008. Then it was hauled and there was no sign of blisters.

There were lots of tenacious barnacles that were scraped and sanded off. The gel coat was thinned in many places, so I decided to do an epoxy barrier coat as a primer to protect the gel coat (and laminate) from future wearing from sanding. I used rolled on West System epoxy, cant say how many coats or the thickness. I will say that I did a terrible job, with runs and sags all over the place. I did not know this until the haul out. I spend the entire month sanding the hell out of the bottom. The epoxy cured with a "mottled" finish. I sanded and sanded and would sand thru one layer of epoxy, yet still not have the anti fouling sanded off. Picture attached. Anti foul layers are brown and grey. Gel coat is whit and grey.



SO what should I do? I am thinking I need to use a primer to protect the bottom. But I am worried that I will have the same issue with blisters. I could use a non epoxy primer but epoxy is very hard.
I was thinking of Sea Hawk Tuff Stuff. I looked at a Sea Hawk video of the Tuff Stuff application, but was not impressed. The epoxy went on with a texture and not at all smooth....

Any ideas, experiences, and recommendations?

thanks!!!
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Old 14-05-2017, 19:00   #2
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Re: Blisters in barrier coat.

I'll bite. If it were mine, I would not skimp and do a proper job. Sand down as far as needed. Then go from there. If from there means a whole new fiber layup then it means just that. If it doesn't sand through the gel, then even better!
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Old 14-05-2017, 19:20   #3
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Re: Blisters in barrier coat.

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Originally Posted by hobopacket View Post
I'll bite. If it were mine, I would not skimp and do a proper job. Sand down as far as needed. Then go from there. If from there means a whole new fiber layup then it means just that. If it doesn't sand through the gel, then even better!
Maybe I was not clear..
The lay up is fine, no blisters are in the lay up. The gel coat had blisters and were sanded and filled. I just need to pick a coating next...

thanks for your reply.
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Old 15-05-2017, 05:15   #4
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Re: Blisters in barrier coat.

Ah, so am epoxy barrier coat? I have no idea what to recommend.
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Old 15-05-2017, 06:02   #5
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Re: Blisters in barrier coat.

Do not use micro ballon filler underwater!!!! Im having the same issue with my boat. Use cabosil.....do it right...
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Old 15-05-2017, 06:57   #6
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Re: Blisters in barrier coat.

I have a very similar issue, PO had the boat barrier coated. I am sure it was because he was told that is the best bottom job.
A year or so later when I pull the boat for survey, I notice many .25" blisters, "pox" I call them that do not penetrate into the laminate, just into the gelcoat.
I did nothing and every year there are far fewer of them, this year there were almost all gone.
I feel sure that what happened was the yard pulled the boat in one day, pressure washed and next day sanded it to Gelcoat, then epoxy barrier coat and bottom paint, job finished in less than a week, yard got paid, owner happy to get his boat back before the weekend.

However I believe what happened was the Epoxy barrier coat sealed in moisture in the gel coat, which led to these tiny shallow pox.
Gelcoat is not a water barrier I don't think.
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Old 15-05-2017, 08:14   #7
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Re: Blisters in barrier coat.

Quote:
Originally Posted by a64pilot View Post
I have a very similar issue, PO had the boat barrier coated. I am sure it was because he was told that is the best bottom job.
A year or so later when I pull the boat for survey, I notice many .25" blisters, "pox" I call them that do not penetrate into the laminate, just into the gelcoat.
I did nothing and every year there are far fewer of them, this year there were almost all gone.
I feel sure that what happened was the yard pulled the boat in one day, pressure washed and next day sanded it to Gelcoat, then epoxy barrier coat and bottom paint, job finished in less than a week, yard got paid, owner happy to get his boat back before the weekend.

However I believe what happened was the Epoxy barrier coat sealed in moisture in the gel coat, which led to these tiny shallow pox.
Gelcoat is not a water barrier I don't think.
This situation as well as that of the OP seems to confirm an opinion of mine that has been criticized elsewhere in this forum. That is, if you have an older boat, mine is 1979, that doesn't have any blisters or other hull issues it makes little sense to then barrier coat it as an "extra precaution" against something that hasn't happened in the 30+ years it's already been in the water.
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Old 15-05-2017, 08:19   #8
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Re: Blisters in barrier coat.

I have done two blister repairs on 36' boats. One was a a bunch of bigger blisters, some requiring cloth, and the other was like yours, what I call pox. After the blisters are repaired, like you did, you need to build up a pretty thick barrier coat over them. With West it is like 6 or 8 coats. I used all West System the first time, but the second time I started with West System and during the process found a product at epoxyproducts.com that they advertise as staying waterproof forever ish. I put 3 coats of their epoxy over the West epoxy. They say on the website that if you ever get water into your polyester/glass lay up again it will be from the bilge. It was easier to use than West System. Good luck, it is hard, shoulder wearing work.
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Old 15-05-2017, 08:20   #9
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Re: Blisters in barrier coat.

I'd say barrier coat an older boat, just be sure you not sealing water between two impermeable layers.
In other words, make sure its dry before you do.
I feel sure my PO was sold on the better bottom job, I can hear it now, better barrier coat it before you have problems, look over here. I bet this guy wishes now that he had, salesman showing a boat undergoing blister repair.

I feel sure it made my boat harder to sell, probably would have been better to just have slapped on another coat of bottom paint
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Old 15-05-2017, 17:03   #10
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Re: Blisters in barrier coat.

The best barrier coating that I have encountered, and used by many of the shops in the Annapolis area, is actually made by Sherwin Williams. It was originally developed for the Navy and restricted for application by certified pros and only available in large quantities. It's identified as follows and is available in 1 gal cans: Formula 150 Type III, N10V00350, Part A, #640182580 & Part B, #640182168. You can roll it on. I previously had 2000E and after 5 years it became osmotic and I ended up with a massive blister problem. Have this on since '07 and the bottom is dry! You can get it thru your local S/W retail store. Check your hull first with a moisture meter before applying to be sure your dry, sand bottom and then apply. JMHO
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Old 15-05-2017, 18:14   #11
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Re: Blisters in barrier coat.

Quote:
Originally Posted by Scrimshaw4 View Post
The best barrier coating that I have encountered, and used by many of the shops in the Annapolis area, is actually made by Sherwin Williams. It was originally developed for the Navy and restricted for application by certified pros and only available in large quantities. It's identified as follows and is available in 1 gal cans: Formula 150 Type III, N10V00350, Part A, #640182580 & Part B, #640182168. You can roll it on. I previously had 2000E and after 5 years it became osmotic and I ended up with a massive blister problem. Have this on since '07 and the bottom is dry! You can get it thru your local S/W retail store. Check your hull first with a moisture meter before applying to be sure your dry, sand bottom and then apply. JMHO
I'll second the Sherwin Williams product. It's a commercial marine barrier coat...it's puke green, and it's less than half the price of the Interlux/Pettit/Etc. products. It's certainly cheaper than going the West Systems route, which will bankrupt you. That said, the last coat should be a barrier product by the same manufacturer of whatever bottom paint you're putting on, just to ensure compatibility.

lostsoul, if I'm reading your post correctly it sounds like you have epoxy on top of old antifouling paint. Is that correct? And you left the boat in the water for 9 years straight?

Personally, I would do one of two things A) do it right and take everything off, down to the gelcoat, and rebarrier coat it properly. I'd let it sit after being stripped for a month or two before reciting. B) Slap some anti-fouling paint on it and go sailing.

I think given the fact that you have this cluster$*%& of different coatings and filler in different layers that putting anything on top of it other than anti-fouling would be a waste of money and make any future stripping job all the more difficult.
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Old 15-05-2017, 20:01   #12
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Re: Blisters in barrier coat.

Quote:
Originally Posted by Bluemansailor View Post
Do not use micro ballon filler underwater!!!! Im having the same issue with my boat. Use cabosil.....do it right...
Blueman, what is the issue with micro ballons vs cabosil?
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Old 15-05-2017, 20:06   #13
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Re: Blisters in barrier coat.

Quote:
Originally Posted by a64pilot View Post
I have a very similar issue, PO had the boat barrier coated. I am sure it was because he was told that is the best bottom job.
A year or so later when I pull the boat for survey, I notice many .25" blisters, "pox" I call them that do not penetrate into the laminate, just into the gelcoat.
I did nothing and every year there are far fewer of them, this year there were almost all gone.
I feel sure that what happened was the yard pulled the boat in one day, pressure washed and next day sanded it to Gelcoat, then epoxy barrier coat and bottom paint, job finished in less than a week, yard got paid, owner happy to get his boat back before the weekend.

However I believe what happened was the Epoxy barrier coat sealed in moisture in the gel coat, which led to these tiny shallow pox.
Gelcoat is not a water barrier I don't think.
Sounds like my boat. Mine may have been wet. probably it was wet. At least the laminate is fine. I would not usually overcoat vinylester with epoxy but wanted to preserve the hull shape from future sanding.

I guess I will use another epoxy barrier for the same reason. What else can I do?
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Old 15-05-2017, 20:10   #14
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Re: Blisters in barrier coat.

Quote:
Originally Posted by billdre View Post
This situation as well as that of the OP seems to confirm an opinion of mine that has been criticized elsewhere in this forum. That is, if you have an older boat, mine is 1979, that doesn't have any blisters or other hull issues it makes little sense to then barrier coat it as an "extra precaution" against something that hasn't happened in the 30+ years it's already been in the water.
Bill, I agree with your opinion of not barrier coating a good boat. But I dont think my boat applies since it was peeled and relaminated with vinylester. Although the theory is similar. My boat did not have blisters after the bottom job.

thanks!
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Old 15-05-2017, 20:13   #15
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Re: Blisters in barrier coat.

Quote:
Originally Posted by a64pilot View Post
I'd say barrier coat an older boat, just be sure you not sealing water between two impermeable layers.
In other words, make sure its dry before you do.
I feel sure my PO was sold on the better bottom job, I can hear it now, better barrier coat it before you have problems, look over here. I bet this guy wishes now that he had, salesman showing a boat undergoing blister repair.

I feel sure it made my boat harder to sell, probably would have been better to just have slapped on another coat of bottom paint
Yes, I have an old boat with a new bottom. But I am pretty sure that the boat was wet when I applied the barrier coat. In my case it was applied as a primer/sealer for the gel coat to keep it fair for future sanding. I have the same issue now...LOL.
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