Valiants are infamous for their blister problems. Here’s my take.
Blisters form on the hulls of many different boats, for different reasons, and no one anywhere seems to have all the answers. I am just learning about boat blisters, so I have little qualification to talk about them. But I’m going to anyway. Sometimes blisters take the form of same-sized tiny little bubbles that are probably just spots where the paint is bubbling up. Other times they can become hand-sized. They can form on just the topsides (out of the water) and not the hull. Or vice versa. This is the important thing: most of the time blisters are merely cosmetic–they don’t affect the integrity of the hull whatsoever. They will not cause your boat to sink, bottom line. I am told that occasionally blisters can get so bad that they pass entirely through the hull, causing the entirely thickness of the hull to delaminate in a particular area. I have never seen a blister like this, I’ve never heard of a boat sinking from blisters, and honestly it’s hard for me to imagine how exactly that would happen. Even if the blister formed a weak area in the hull, it’s not like it ever gets weak enough to spontaneously form a hole and let the ocean into the boat. One thing is certain: blisters are very good business for surveyors and boatyards. I would guess that people spend more money on getting blisters ground out and reglassed and faired and repainted than any other single item of boat maintenance except bottom paint. In the case of the Valiant, the most popular theory is that the blisters were caused from the particular kind of fire-retardant resin that Uniflite used. Eventually they caught on and fixed it, but not before building a few hundred boats that seem cursed with an unfixable blister problem.
From experience, I can attest that the fiberglass in our boat oozes a black gooey pus. When I crawl way back in the lazarette where the fiberglass is bare and undisturbed, I can see some spots of black ooze, which I studiously try to avoid. The ooze is not very runny, but neither is it dried and solid. It’s the consistency of a really thick partially dried honey. And it’s really black. Nasty looking. Like someone spilled something on our boat five years ago and never cleaned it up. Captain Bob has said that it’s either really basic or really acidic, because he says it burns a little bit on the skin. Anyway, my guess is that this is the stuff that causes the blisters. If there’s a little pocket of it in the fiberglass near the hull, then it can pull water in through the gagillion waterproof layers of barrier coat and bottom paint (how it accomplishes that no one can explain) via osmotic pressure, forming a blister.
I have known Valiant owners that took their boat to the factory in Texas (after Uniflite closed up shop in Bellingham), had the entire hull ground down to bare fiberlass, glassed over it, epoxy barrier coated it, bottom painted it, and STILL had the blisters come back within 10 years. Now tell me how that’s possible.
In 2005 at Marina Real in San Carlos, MX, Syzygy (then Sunshine) had its hull ground down to bare glass, a heavy layer of fabric glassed on, 5 layers of epoxy barrier coat painted on top of that, and then a couple coats of an ablative antifouling bottom paint on top of that. The previous owners had a guy named Arturo do it, and said that his work was top notch. No blisters have reappeared (YET).