1. In the fiberglass world, fair means sand/polish flush with the surrounding area and/or proper profile?
Yes, smooth it out, make it flush. Generally speaking in this case, make a nice flat area so that the new glass has something to attach to. A flange of sorts.
2. Doesn't it go without saying that if the that outside sustained that kind of damage and is now slightly flexible that the inside layer is now compromised?
Not necessarily, you have to look. But if the inner skin is compromised...
Basically, what I'm saying is do the repair exactly the same as in the article, but instead of using the fishing line and going from the inside, since it's on a flat area of the hull, just glue the new cloth to the outside of the inner skin. Fiberglass noobs have much better luck bonding this way. The "fishing line" technique is very cool, but it isn't the easiest way to get a solid bond and it takes longer. From memory, I think in Rick's article he repaired the bottom of a hull, which doesn't have a layer of foam. It's necessary to go from the inside on that one.
3. You reference the "blind repair" article but even in that one they ground through all layers, probably biggest confusion.
Yes. What I'm suggesting is leaving the inner skin so you have a solid backing to glue new glass to. You can absolutely do it that way, but I'm giving you a fool proof way that's less technical. I would get rid of some of the broken glass on the inner skin, but generally leave it for backing. There is no benefit to gluing the new glass to the inside of the skin on your particular repair other than to impress your friends...which might be worth it.
