Barrier Coat and Blisters

[Andy]

I'm in the process of completely striping the paint of the bottom and getting rid of the many blisters on my 1981 Catalina 30. I am going to put a barrier coat on and was wondering if I should fill in all the popped blister holes with an epoxy, or if I can just paint on the barrier coat over them. There is about 75 blister the size of a quarter after I have cleaned them out. There is also one spot where there were several in one area and ended up scraping of a 12"x12" section of the gell coat.Also, can anyone recommend a good brand of barrier coat?

 

[David Sandowich]

blisters

the blisters need to be filled with a marine epoxy and flared to the hull.three to five coats of barrier coat needs to be applied depending on the quality you buy. Make sure the hull is dried out. See a marine store you trust for specifics. I'm in the process of doing the same with my '85 cat 30. only other option is to shave off the layer of fibergalss and gel coat and relas the boat. big job , lots of money and not one for handyman.

 

[Jon Kellams]

Blisters

Just went through same with my 1990 C-30. I had the hull sandblasted, ground out the blisters, filled and faired them. Then did 4 coats of Interlux Interprotect 2000 Barrier coat followed by 4 coats of Interlux Micron CSC Extra. Looks great and I am told I shold be blister free for many years.

 

[LaDonna Bubak - Planet Catalina]

Watch out for small blisters!

You can see problems in the future if there are any teeny tiny blisters that haven't really formed yet. If you don't fix every blister before you put the barrier coat on, you could get big old blisters not too long after you splash her. The reason is that the water is trapped in a tiny little pocket & once the barrier coat is on, it has no place to go but sideways. This can make a big blister that otherwise wouldn't have been that big of a deal if you hadn't barrier coated. As far as filling the blister holes - ABSOLUTELY! Fill them with epoxy filler & fair them VERY well, otherwise your boat will suffer in performance cuz the bottom has a craterous (is that a word?) surface. When I barrier coated my boat, I used West Systems with their barrier coat additive. Seems to have worked well so far (2 years). Good luck!LaDonna

 

[joe martinez]

barrier coat

the key to a good blister repair job is drying out the hull, and there's no real shortcut.(except skirting it and renting a dehumidifier) humidity under pieces of reynolds wrap taped to the hull is a generally good indicator of moisture -- if you see condensation under it, there is still moisture. be patient and let it dry. i prefer fiberglass mat to fill repairs, thats what the boat is made of, and a top coat of polyester resin, faired poperly. the moisture barrier that i prefer is vc coal tar epoxy. 1 coat on all repairs first, then 5 coats on the rest of the bottom. it rolls on really smooth if you keep a little thinner on the roller, it dries fast, and most bottom paints adhere well to it. remember, be patient, and good luck.

 

[Dave Ullrich]

Beware of pencil point blisters and use a Moisture

I just went through the blister thing with my 83 Cat 30. Make sure you look for what seems like little "pencil dots" or periods. These are tiny blisters that need to be taken care of before sealing. If not, they will be grapefruit sized in no time. If you've got a lot of these small blisters, it time to tink about a full jellcoat peal. Also I would at minimum dry out the boat for 4 months thecn check it with a moisture meter. Don't seal if it reads above 3%!

 

[Carey Curtis - DOWN EAST]

blister repair

There is an excellent article on blister repair at www.yachtsurvey.com. Above all, I would NOT sandblast - many boatyards do it because they don't have the expertise to do anything else. Peeling is the correct procedure if you are willing to make the investment.