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post #5 of Old 03-29-2009 Thread Starter
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maine sail, thanks for the post!

The hull of my boat is dry (as evidenced by both moisture meter readings and inspection of laminate, as I had a chance to drill a few holes ). That said, something happened today that underscored for me the importance of barrier coats (and, let me post here something that suggests, to me anyway, that even a really bad barrier coat is better than none - see the end of this message).

I am somewhat torn on whether to hire someone or do it myself. The cost is not an issue. I am well aware what this would cost, and would not mind paying for a quality job. That said, I know that other than myself, no one else would care enough to do it as well (I've dealt with a few contractors before, as I mentioned ). It is a tough job though, and I am wondering if letting someone do it "good enough" is an easier way out.

I also do know that preparation (sanding/stripping or whatever method of paint removal that'd be chosen) is the hard part. I can roll barrier coat epoxy and time it like anyone else

My boat is currently on land and been there for over 6 months, so this is probably as good a time as any to do it. If I launch now, I do not plan to be out of the water for a long period of time and doing barrier coat during a relatively short haul out is probably not optimal.

Now, here is the interesting point.
I had in the past sanded and inspected a number of areas of my boat's bottom. There is no barrier coat now - only multiple layers of paint. Under it I found a gelcoat in reasonable condition - a few cracks here and there, a bit of osmotic pinhole occasionally, but no blisters, generally high quality laminate underneath and overall everything looked good enough that I did not consider barrier coat to be necessary until now.

Today I removed the old ground plate, planning to replace it. Unlike other hull fittings, ground plates are not supposed to be sealed (according to installation manual) and this one was not. It was applied to bare hull and bolted, so water could (and did) enter behind it. Here is what I found there:

Larger image is here:

I am sure it is evident even from this cell phone photo that this is NOT a gelcoat in good condition. In fact, the entire area under the ground plate is completely cracked. Worse yet, there are a few holes in fiberglass surface where resin was completely washed out and all that remains are dry glass fibers. This area is in stark contrast to anywhere else on the bottom, including area directly adjacent to it (you can see white decent gelcoat just outside the edge of the ground plate). Some of this can be explained by water entering through bolt holes (which were also not sealed) and penetrating laminate sideways through the fibers. But this does not explain the entire area condition and the fact that the damage is specifically limited exactly to the shape of the ground plate.

Unless there is some electric weirdness going on (which I doubt) the only real difference here that I can see, is that this area of gelcoat was not covered by bottom paint. So - even ablative bottom paint provides a measure of protection to gelcoat, that is not available otherwise. While this may not be entirely scientific, I think barrier coat should work at least as well as ablative paint
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