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Author Topic: What to Do About Gel Coat Voids  (Read 512 times)

November 29, 2018, 05:46:05 PM
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mshugg

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What to Do About Gel Coat Voids
« on: November 29, 2018, 05:46:05 PM »
Been working on the bottom off my CCP rebuild, and I'm running into a problem with tiny voids in the gelcoat over the aft 4 to 6 feet of the hull bottom.  They're about the size of a pencil tip, or a bit larger. They're not blisters.  There's no indication of them every being wet, and there's no discoloration of the underlying glass.  They appear to have been there since the boat was built.  I'm not sure if they were caused by air in the laminate or gel, or outgassing as the hull cured, or even contaminates between the hull and gel when the hull was laid.










I've been treating them like blisters, grinding them out with a Dremel and filling with thickened epoxy, but every time I sand the hull flush, more appear.  So the question is:  What should I do? 

1.   Continue grinding and filling until they stopped appearing, then prime, fair and paint?

2.    Sand the gel off, then prime, fair and paint?

3.   Sand the gel off and sheath section of bottom with a layer of glass?  1708?  12 ox Biax?   10 oz Cloth?  (I'm using epoxy at this stage.)  Then prime, fair and paint?

4.   Sand the gel off and sheath the whole bottom with a layer of glass?  Then prime, fair and paint?

If I'm correct that they're a flaw in the original  layup, the hull lasted almost 40 years without the problem surfacing.  How obsessive should I be?

November 29, 2018, 06:39:22 PM
Reply #1

dirtwheelsfl

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Re: What to Do About Gel Coat Voids
« Reply #1 on: November 29, 2018, 06:39:22 PM »
Waterline down or whole hull??

November 29, 2018, 06:42:59 PM
Reply #2

mshugg

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Re: What to Do About Gel Coat Voids
« Reply #2 on: November 29, 2018, 06:42:59 PM »

Waterline down or whole hull??

Only below the waterline, really between the chines, and mostly aft.

November 29, 2018, 06:58:54 PM
Reply #3

RickK

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Re: What to Do About Gel Coat Voids
« Reply #3 on: November 29, 2018, 06:58:54 PM »
This is in front of the work you're doing in the aft?
I used Duraglass and then moved on to high dollar fiberglass bondo from auto supply houses to get stuff that didn't get pinholes (there is not one that is perfect).
Rick
1971 "170" with 115 Johnson (It's usable but not 100% finished)

1992 230 Explorer with 250 Yamaha

November 30, 2018, 09:49:41 AM
Reply #4

mshugg

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Re: What to Do About Gel Coat Voids
« Reply #4 on: November 30, 2018, 09:49:41 AM »
This is in front of the work you're doing in the aft?
I used Duraglass and then moved on to high dollar fiberglass bondo from auto supply houses to get stuff that didn't get pinholes (there is not one that is perfect).

Yes,  It's the gel in front of the hook.  They're not really pin holes in that I haven't applied any fairing yet.  I don't want to jump in to fairing without doing something to assure that the underlying glass/gel is sound. 

November 30, 2018, 12:26:29 PM
Reply #5

dirtwheelsfl

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Re: What to Do About Gel Coat Voids
« Reply #5 on: November 30, 2018, 12:26:29 PM »
I would just take the gel down til you get thru the pock marks then...

Then commence with some fairing compound then prime. Prolly gona take a couple fills to get it all of course...

November 30, 2018, 12:36:47 PM
Reply #6

mshugg

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Re: What to Do About Gel Coat Voids
« Reply #6 on: November 30, 2018, 12:36:47 PM »
Thanks Dirtwheels.  That’s where I landed.  I think, after I’m down to glass, I’ll roll on a coat or two of untickened epoxy, then sand fair and prime.  Sound good?

November 30, 2018, 06:36:29 PM
Reply #7

dirtwheelsfl

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Re: What to Do About Gel Coat Voids
« Reply #7 on: November 30, 2018, 06:36:29 PM »
Do the unthickened then mix up a homemade microballon slurry and go wet on wet. Itll really fill all the pock marks and the combination of the 2 will make it alot less pinhole-y.    Let the unthickened tack up a bit first...

December 01, 2018, 07:43:50 AM
Reply #8

mshugg

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Re: What to Do About Gel Coat Voids
« Reply #8 on: December 01, 2018, 07:43:50 AM »
Thanks, Dirt.  That's the plan.

 

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