Opinions on gelcoat condition, please

[moonie5961]

Hey all,

I realize that these pictures aren't the greatest- but would you guys please let me know what you think of the condition of this gelcoat?
There are discolorations everywhere-dark blemishes, and I'm not sure what they are.

I have a hunch that they are old blisters which have shriveled up- and this is what is left. I searched high and low to find out what dried blisters look like, but couldn't find anything like this. My other thought is that the old barrier coat was applied to a hull which was not allowed to dry-and this is the result of moisture being trapped between the gelcoat and the epoxy.

This was found beneath many layers of antifouling, a poorly applied barrier coat-which was actually applied over one layer of ablative paint, and a mystery pink/purple layer. There are absolutely no places where it looks as if blisters were ground out and filled with epoxy- so this leads me to believe that this may have been an attempt at a pre-emptive barrier coat, albeit a very poorly executed one.

I'd very much appreciate hearing what you all think. If you are so inclined, please click on the picture to zoom in. I think that they show the situation pretty clearly.

Thank you!

PS I feel that it is important to note that these discolorations do not extent into the laminate at all, I don't think. There are a few spots in the photos where it is apparent that I sanded through the gelcoat, and the fiberglass is exposed. In these places, it looks to me as if the chopped strand mat is in good condition, and shows no sign of un-saturated fibers or anything of that nature.

[moonie5961]

anybody? por favor?

[bcooke]

As you suggested in your posting, the pictures really don't show enough detail to make a real diagnosis. Sometimes you just have to see it in person to get a good sense.

Various colored layers are pretty typical. Exactly what those layers are can be very difficult to identify.

Since there is no evidence of structural failure I wouldn't be too concerned about it. Maybe there are/were some blisters but they clearly are not causing a problem.

Since your thread topic asked for opinions on the gelcoat I will say that like most any older boat, the gelcoat is ugly. Gelcoat is a cosmetic layer so what that means is up to you to decide. If you don't like it, sand it off and apply your bottom paint. If you are not bothered by it, slap on some bottom paint and go sailing.

[Case]

The gelcoat in the pictures look to be of the bottom...

Its common for sailboats to have more than one layer of gelcoat at the bottom, especially at the very bottom (for sailboats with internal ballast).

My sailboat had 2 layers of gelcoat at the bottom of the hull. They were chunky and pitted at the very bottom (I have a full keel). I even had blisters between these two layers of gelcoat! I popped the blisters and filled them with epoxy. No problems since then.

I would say this much: Don't worry about it. Just fill in, paint over and go sailing. I bet your house is in worse shape if you look really, really closely...

- Case

[moonie5961]

Thank you guys very much!

I was just questioning whether these were hibernating blisters, or just discolored spots. My concern is that if these are latent blisters, I might need to grind and fill them all. There are a LOT of them! I have this vision in my head of these hundreds of little spots blossoming from innocuous boat freckles into full blown boat pox as soon as it hits the water. But, they don't go far into the laminate or appear to be trouble makers.

I'm really conflicted. Part of me thinks that a barrier coat is necessary, but most of me hates the thought of it after reading all of the advice here. And, ALL of me hates the thought of stripping another failed barrier coat from the hull with a sander.

I will be putting the boat into the warm Gulf of Mexico eventually, and it will be in the water year around-so no drying out time over the winter.

I would really rather just slap on some bottom paint and see what happens...
I have heard such great cases made both in favor and against barrier coats that I don't know what to do. blah!

Thanks for taking a look, fellas

[sail_fix]

I once fixed about 30 or 40 large gel coat blisters, on my former boat. This was in the 80's. While some were a couple inches across, none went beyond the thin layer of mat that was under the gel coat (beyond that were multiple layers of roving).
I got a lot of advice, all well meaning, and some rather contradictory. At that time several local yards were pushing a spendy scheme of grinding off the gel coat and coating the whole bottom with epoxy. As the years passed, the flaw turned out to be that only some of their work held up well, and when it failed (sometimes spectacularly) due to poor prep or application. No matter what your opinion of how frp boats were constructed originally, an outdoor dusty, hot, cold, wet, dry (etc.) boat yard is not necessarily an improvement in laminating ambience!

I got some good advice from one of the founders of Cascade Yachts about blisters. He said, basically, to not agonize so much and just fill 'em with good quality stuff (no clay filler like the old Bondo) whether poly or epoxy based. If the blister went into the laminate, fair back the divot and lay in some cloth circles to built it up.
Fair it all out with a "da" sander and ... move on.

He was against removing any more gel coat than needed for the spot repair at hand, since the gel coat is there is seal the laminate and has an important job to do.

So I fixed all the ugly-looking blisters.
I admit to a moment of high tech weakness for the then-current newest blister prevention idea, and overcoated a section of bottom on one side with the newest product at the time, "Interprotect." Stuff hardened into a very rough surface that took a lot of fairing. That was on less than a quarter of the bottom.
Years later there was no recurring blistering on any of the bottom.
Lessons learned.... there's a bit of magic along with some quantifiable science in all this stuff!
:)

L