Sanding, Re-Coating, Sanding, Coating Again

After all the excitement of flipping the hull over and seeing the smooth epoxy coating on the bottom, the hard (one might call it tedious) project of fairing the bottom and topsides was a little harder to get into. I (Drew) started right away though, wanting to get it over with and to move along to more interesting tasks.

I've spent a good deal of time sanding and recoating the hull to get it smooth and fair (more or less). This is very time consuming. The first go-round I went over the whole bottom with 80 grit on the belt sander. There were bubbles under the coat of epoxy that I wanted to expose so that the next coat could fill them. The mylar trick was supposed to obviate the need for additional sanding and coats of epoxy, but because of the bubbles I decided to go about the sanding and re-coating process. I think that it needed to happen anyway, because the surface was somewhat uneven and needed fairing. I ended up sanding into the fiberglass in some places because of the bumpiness, and it became much more obvious when the low areas had their sheen and the high areas were all roughed up.

This prepared the bottom for the first (and I had hoped, only) coat of epoxy after the wetting out of the glass. I coated the bottom, hoping to come back and do some sweet finish sanding and be more or less done with it. As mentioned, it didn't really work out that simply.

I hadn't realized how far we were from a smooth, fair bottom. Also, this coat picked up some dust or something and ended up pretty rough. Thankfully when I sanded again I didn't go through the epoxy to the fiberglass except where I was feathering out the glass on the garboards. The feathering looks good by the way. I scraped all the rough spots out with the scraper, then went back over everything with the orbital sander and 80 grit paper. Then I rolled on one more coat of epoxy on, which I think with a sanding to get all the whatevers out will be all we need. I sure hope so, because sanding all this epoxy and glass feels like turning expensive glue into dust (and cancer).

After reading a little more about glassing I learned that all the problems with bubbles and less than perfect transparency can be dealt with by raising the temperature of the epoxy. This makes it thinner, which in turn allows the bubbles to work themselves out before the glue starts to set up.

Apparently 70 degrees is like the absolute minimum for a perfectly clear fiberglass layup. That's probably about where we were when we did ours. Our epoxy consistency was more or less like a thick syrup. This thing I read said that it should be about as thin as water for the best wet-out results. So, on the next boat we need to remember to get the epoxy up to about 85 degrees when we're doing fiberglass so we get better flow. Also, we should spend more time sanding prior to putting anything on. I think everything post-layup would have gone much better if the surface was better smoothed out to begin with.

To say it mildly, I'm super tired of sanding and sweeping and vacuuming, but there's still a lot more cleanup left to do. I've got a hair dryer now to warm up the epoxy in all those fills on the sides. The wood flour mix becomes super hard with the epoxy fully cured (I should have scraped them off when I knew it was the right time, when the glue was still a little elastic), so it's too easy to dig in on either side of the fill. The hair dryer warms and softens so I can scrape the stuff off. Baah!
Well, we're getting there. Soon another part of the boat will be presenting problems of its own.