: I'd be interested to hear comments from others who might know for sure if
: there is a strength penalty from not doing a fill coat. My original idea
: for this layup came from the builder formerly known as... sorry, I can't
: even use the initials - it's bad luck

I seem to remember that discussion.
I think the idea was that the second layer was sacrificial.
If you stopped sanding when you hit the second layer, the first would remain
intact.
One Ocean Kayaks has a comparison of various epoxies on their site, and
the article also addresses the issue of fill coats. Vaclav seems to think
fill coats are very important, since if the fabric is not buried deeply enough
you get more stressed areas, or something to that effect.