[harbin2]

After I removed all the paint off the bottom of my West system barrier coated bottom, I found about 25 of these little pin holes in the barrier coat. I drilled them out and filled them with epoxy filler. They ranged from 1/16" to 1/8" in depth. I think they were probably holes in the barrier coat caused by bubbles when it was applied that popped as the epoxy cured. Can anyone please confirm or deny that?

 

[brak]

yes. run for your life

It is a void, for sure. It may be a "blister" (i.e. void caused by water intrusion that subsequently washed out the resin) or a result of initial layup problem.

 

[Capnblu]

I agree.

 

[bubb2]

Harbin, you say you found them in the barrier coat? If they are in the barrier coat then they are NOT blisters and nothing to be worried about. If they are in the gel coat or deeper then they are blisters.

 

[sailingdog]

It also could be a fisheye in the barrier coat caused by improper preparation of the hull prior to barrier coating the boat.

 

[PorFin]

Yeah, if they're 1/16"(+) they are almost certainly deeper than the barrier coat since most barrier coats are recommended to be between 20-30 mils (i.e., up to 1/32" give or take.) Of course, whoever applied the barrier may have gotten all fired up and gone really heavy with the epoxy but I wouldn't bet on it.

Did any fluid drain out of the holes when you drilled them?

 

[harbin2]

There was no fluid in any of them. The depth varied but all appeared to be filled with dried bottom paint. The boat has been out of the water since November so they have had a chance to dry.
I know blistering is a gelcoat phenomena but I believe I read somewhere (I think in the Interlux Interprotect literature) that barrier coat can also blister. And anything is porous with time and pressure.

SD - what is a fisheye?

I now have them all filled but my interest is in not ending up with the same thing after I apply the additional barrier coats I'm planning on applying next. So I'm trying to figure out what caused them.

 

[St Anna]

harbin
I found a similar thing recently. What it turned to be was that the re-apply time was not 'adhered' to for the barrier coat. It seperated in places causing an appearance of minute bubbles.

I sanded the old coat off, epoxied, sanded, painted etc.

 

[sailingdog]

SD - what is a fisheye?

I now have them all filled but my interest is in not ending up with the same thing after I apply the additional barrier coats I'm planning on applying next. So I'm trying to figure out what caused them.

A fisheye is a defect usually found in a coating, like paint or in this case barrier coat, that is caused by some oil, wax, grease or silicone residue left behind on the surface from improper preparation. It usually has this appearance:

 

[PorFin]

There was no fluid in any of them. The depth varied but all appeared to be filled with dried bottom paint. The boat has been out of the water since November so they have had a chance to dry.
I know blistering is a gelcoat phenomena but I believe I read somewhere (I think in the Interlux Interprotect literature) that barrier coat can also blister. And anything is porous with time and pressure.

SD - what is a fisheye?

I now have them all filled but my interest is in not ending up with the same thing after I apply the additional barrier coats I'm planning on applying next. So I'm trying to figure out what caused them.

Sounds like you're safe for now. If they were allowed to thoroughly dry before you filled them, and you filled them properly, you shouldn't have any surprises next time you haul.

Blistering under the barrier coat is my major headache this winter. A PO apparently applied the BC over a wet hull. I've got hundreds that I ground out, and I'm waiting a few more weeks to fill and fair. Fortunately, I've had the hull in heated storage. Had I known the extent of the problem when I hauled, I would have gone for a full peel instead of just addressing them individually.

 

[sailingdog]

A gelcoat peel is usually the best solution for serious osmosis blistering..but a very drastic step.