: Epoxy will bond to vinylester, but leave a roughly sanded surface for the
: best bonding.

: The yellow color looks like Kevlar to me, it could be that the resin has
: yellowed over the years, but the weave also looks like something you would
: expect of Kevlar. If when you sand it, it gets all fuzzy and hard to sand
: you will know for sure, but I'm willing to bet it is Kevlar and you will
: hate sanding it.

Another tip-off is that it's on the inside of the hull. Except for racing boats Kevlar is usually the innermost layer to get it's benefits without subjecting it to abrasion. If Kevlar is abraided it gets all fuzzy and nasty looking and is hard to repair neatly. It's always yellow,too.