cc0080793 wrote:

I have a 12' x 50' Catamaran Cruiser Houseboat....
I was told when we first put it in the water to watch for "blisters" in the
fiberglass hull a few years down the road. Well... here I am a few years
down the road (3 years to be exact), and I DO see some half-dollar sized
places on the hull that must be the aforementioned blisters

uh-oh


Is this "blisters"?

Yep, it sure sounds like it.


What to do?

Are they above the waterline or below?

Either way, the answer is to pop one and see what comes out. If nothing,
then you're OK for now although you'll probably want to do at least a
cosmetic repair at some point.

If you get a slightly obnoxious odor and some colored gunk dribbling
out, then you've got a big problem... the classic hull-destroying
blister pox. What you *don't* want to see is a corresponding dimple
eating into the fiberglass under each blister. They can (and have) eaten
right through hulls. I've seen blisters the size of softballs... even
when repaired that hull wasn't worth much IMHO...


... Is this something I could fix myself, or does it need
"professional" work?

Either way you can fix it yourself if you're handy, and the cures aren't
that far apart. Besides, if you hire a pro to do it, you *still* need to
know how to do it yourself so you can check on him.


Some have said painting the glass hull with an anti-fouling paint will help
prevent this

No, it won't. Painting with a water barrier (usually epoxy) will help.
Antifouling prevents barnacles, not blisters. Starts with the same
letter though

The cure is to grind down each & every blister, fill it with putty, and
then repaint the hull. If you want to prevent the problem from
recurring, even if it's only cosmetic, you'll sand the whole hull and
paint on a "water barrier" type paint and then a nice refinish job over
that. The barrier coat will add to the life of the boat anyway and not
all that much (3 ~ 4 hundred$) to the cost of the job.

Good luck
Doug King