So here's my update for the weekend, lessons learned so far for anyone trying this in the future, and some questions for Okie and the board...
Took about an hour to get the boat covered (kind of windy, so lots of fun). Definately over did it as not all that much dust has landed on the plastic. I'd say at least 95% stays in the bilge area, but gets ALL OVER the bilge. I had plastic covering down past the top of the transmission, but dust is caked all over the engine anyway, and some rug areas next to the front of the engine got hit pretty bad too. I guess in hindsight, this should have been obvious, but I pictured dust flying up and settling more instead of shooting the length of the bildge in each direction. Oh well.
Grinding went well overall. Turns out Okie had the OEM shaft log. The boat is designed beautifully in a lot of ways, but supra seems to have dropped the ball on this one spot. They did not use a shaft log big enough to cover the hole through the hull. Also, at the aft end of the cutout, the hull is extremely thin, but you can see in the picture that they don't put the woven glass over that part. This boat is a family boat bought new, with no major accidents or previous repairs in this area. So it seems to have been built this way for some reason, or whatever they put in that hole area doesnt stick.
In next post, you can see an approx 1" x 3" strip of epoxy (I think its epoxy) that the aft end of the log sits on. That piece seems to have been formed separately from whatever covers the hole. No pic, but looking at the cutout from under the boat before any grinding you could see the 1" piece which dips down a little, and the part covering the hole was flat and higher than the 1" strip.
Pictures:
I was able to pry off most of the glass on top of the log...
IMG_7153.jpg
Amazing what a little acetone and elbow greese can do! Next 2 pics show the area around the log cleaned up pre-grinding. If you look closely you can see the ouline of the fiberglass area as installed from factory...
IMG_7155.jpg
IMG_7156.jpg
Went full hazmat mode like Okie. Wasn't taking any chances. Highly recomend the full face respirator if you don't have one. Very comfortable and no fogging. Also essentially seals twice. Well worth the hundred bucks...
IMG_7173.jpg
The Epoxy and fiber glass keeping the log in place were tinted same bluish grey color as the bilge paint. Here I get down to the hull at the aft end of the log. You can see from the little bits of blue paints that the hull fiberglass didnt cover this area...
IMG_7177.jpg