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[E32-3] What am I looking at here (material under gelcoat that isn't glass?)

Geoff W.

Makes Up For It With Enthusiasm
Blogs Author
Hi folks,

Getting some pics back from the guys currently redoing the bottom on my boat and whatever's going on looks super mysterious to me. For context, when I bought it, I knew it had a veritable rash of tiny blisters down the port side. Tiny ones, like goosebumps - not the kind I'd seen so often in all the "grind and fill" tutorials I obsessed over.

Pic here:

nefpre.png

Well, survey came back as "they're cosmetic, it's an old boat" and a blister never sank a boat so it didn't stop me from moving ahead with the purchase - and still no regrets. That said, the last round of bottom paint it had put on was not done very well, bubbling and flaking off all over the place:

rudder.jpg

So, I decided as part of my mental budget for "initial maintenance", I'd get the bottom stripped, see if there was anything to do about the blisters, and put a better coat of epoxy/paint put on it. So it's up at the shop, and they have ground the paint down to the gelcoat in a number of spots, and bad news - the blisters are beneath the gelcoat. But, the blisters aren't exactly in the fiberglass laminate, either -- it looks like under the white gelcoat is...green paint? Under which is....grey paint (or epoxy)? and the blisters are almost entirely located within this mysterious layer of...something.

Pics here:

IMG_0664.jpg
c3df79e7-6555-48fc-95c6-5d576c30bcf6.jpg
8c619d04-8c4c-435a-b2ba-549ee7c0f088.jpg

So my question to the group is, what's going on underneath the gelcoat? Is the green/grey factory finish or bottom paint from days gone by?

As far as the blisters go, the yard was going to grind out some initial spots to see how bad it would be to take it down to laminate but we've all decided that's pretty cost-prohibitive, given the age of the boat. I feel a little better knowing for sure that the blisters are more or less outside of the glass itself.
 
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Parrothead

Member III
I expect what you're seeing is either stripe gelcoat or backup gelcoat, maybe some of both.

Your hull had three applications of gelcoat. The stripes were masked off in the mold and the hull color was sprayed. The masking was pulled and the stripe color was sprayed, the only part that shows on the outside is where the masking was but the color overlaps the hull color underneath. Finally backup gelcoat was sprayed over the entire hull. It's there to bring the gelcoat thickness up to spec and to block light from coming through. It's pretty unnerving to see sunlight glowing through the hull.

I can't say for sure if Ericson did the same but most other manufacturers kept a drum in the mold shop where they would pour unused and uncatalyzed stripe and non-skid color gelcoat for use as backup. Better to do that than throw it away. Typically the amalgamation of colors would end up being somewhere between olive drab and gray in color.
 

Frank Langer

1984 Ericson 30+, Nanaimo, BC
What you are seeing in that grey/blue area is the actual laminate under the white gelcoat. This past year I also discovered blisters for the first time in our boat, chiseled off about 12 coats of bottom paint, then removed the gelcoat down to that grey /blue layer. We ground out all the blisters, filled all the voids with epoxy, then applied 5 coats of interprotect 2000 epoxy coating, then bottom paint.
A big job, but now I know my boat will be good for a long time yet.
Frank
 

Geoff W.

Makes Up For It With Enthusiasm
Blogs Author
What you are seeing in that grey/blue area is the actual laminate under the white gelcoat. This past year I also discovered blisters for the first time in our boat, chiseled off about 12 coats of bottom paint, then removed the gelcoat down to that grey /blue layer. We ground out all the blisters, filled all the voids with epoxy, then applied 5 coats of interprotect 2000 epoxy coating, then bottom paint.
A big job, but now I know my boat will be good for a long time yet.
Frank

Did you strip the whole bottom of gelcoat down to the laminate?
 

Frank Langer

1984 Ericson 30+, Nanaimo, BC
Yes, though after I chiseled off the 12 coats of bottom paint I was ready to have yard staff take over. They ground off the gelcoat with a grinder, then opened blisters with a Dremel tool. It was all very scary to watch, and took a long time. It was very expensive, but this is likely the last sailboat I buy, and I can't tolerate not having my boat in excellent condition.
Frank
 

Geoff W.

Makes Up For It With Enthusiasm
Blogs Author
Thanks Frank. The piece of mind you have about the bottom is worth every bit of it I'm sure. I have the same feeling that I want this to be a perfect boat, and considered the full gel strip. It bothers me that I'm NOT doing it, but it would also bother me to drop 1/3 or 2/3 of the value of the boat into it right now. We'll see what a couple years looks like with the bottom as it is..... I

'm just as good at convincing myself to spend money as I am at convincing myself to save it. Maybe better at the former. :) With a couple more year's experience I may be confident enough to do a bulk of it myself..... Now I'm just talking to myself...
 
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Frank Langer

1984 Ericson 30+, Nanaimo, BC
Hi Geoff,

There are quite a few factors that contribute to the development and growth of blisters, so it's hard to know in your case how that will go. I had essentially no blisters visible when I hauled the boat two years ago, but could see lots of small blisters when I hauled it after two years, so things had changed dramatically in that short period of time. I was not confident that leaving them for a few more years wouldn't create a much more expensive and problematic repair.

So I would suggest that unless you are fine with blisters of whatever size and shape given the age and condition of your boat, you may want to haul it regularly to inspect the hull to ensure it doesn't get away on you. That will be a bit more difficult to do once you coat everything with bottom paint, but I would guess that large blisters will show through the bottom paint.

Good luck, however you proceed!

Frank
 

toddster

Curator of Broken Parts
Blogs Author
I expect what you're seeing is either stripe gelcoat or backup gelcoat, maybe some of both.

Your hull had three applications of gelcoat. The stripes were masked off in the mold and the hull color was sprayed. The masking was pulled and the stripe color was sprayed, the only part that shows on the outside is where the masking was but the color overlaps the hull color underneath. Finally backup gelcoat was sprayed over the entire hull. It's there to bring the gelcoat thickness up to spec and to block light from coming through. It's pretty unnerving to see sunlight glowing through the hull.

I can't say for sure if Ericson did the same but most other manufacturers kept a drum in the mold shop where they would pour unused and uncatalyzed stripe and non-skid color gelcoat for use as backup. Better to do that than throw it away. Typically the amalgamation of colors would end up being somewhere between olive drab and gray in color.

Well that clears up... some of the mystery. About why I can see daylight coming through the stripes but not the “field.” At least I could before I painted the topsides. And little spots of light where the blisters were. It was a bit scary-looking. Apparently it must have to do with the order in which the masking was removed.
Actually, looking back at that old post is rather enlightening. I painted the new barrier coat up to the bottom of the boot stripe. But even back then, there were some blisters visible within the boot stripe. This year, the only blisters that I found were within the stripe. Should have painted the IP2000 all the way to the top of the stripe.
 
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