Jason - thanks for the comprehensive post and techniques. My thought on re-coring the transom on the inside was that the finished surface wouldn't need the extensive work that would be required on the outside, thus it would reduce labor (and materials). Lumpy edges are ok. I do understand that the access isn't as easy, but I figure by opening the cockpit lockers and removing the Yanmar engine panel, and wooden sides on engine compartment I'd be able to get good enough access to do the work.

Hull painting above the waterline and topsides may not come this year, so it will allow time to defer that expense if the work is done from the inside. I figure any work done below the waterline on the rest of the boat will be done inside where I can, and outside where I can't.

Topside, I don't have a lot of bad areas. I know the area by the anchor locker needs work, the stbd side where the foot rest / original traveler cleat was installed, near the chain plates, and by a few stanchion bases. Since the areas seem to be isolated, and easily sized, I'll see about the inside approach. I may need to reassess this after dealing with the cuts, core layup and refill.

On reusing old skin - would it be worthwhile to use some small screws with holes drilled in the skin to hold it in place? The heads could later be ground off and area faired smooth. Someone also suggested taping plastic around the patch and drawing a vacuum with a pump while the epoxy kicked in on the patch.

On the engine exhaust and cockpit drain through hulls - Did people reuse these, or get new ones to glass in?

Thanks for the vinegar suggestion - the acetone is a ***** to continuously use!