Lynn Tegrity wrote:

Polyester resin cannot be used on a boat using Epoxy resin. Epoxy resin
cures and stays flexible. Polyester resin cures and becomes much
stiffer. The resin that you buy at a auto supply house will be polyester
risen.

This is not exactly true. Polyester products such as gelcoat can be
applied successfully over fully cured epoxy that has been cleaned to
remove any amine blush. I do this all the time on repairs and have never
had any adhesion problems.

IMO, epoxy should be used for repairs and other bonding applications,
since it creates a stronger bond than polyester resin will. For
sacrificial layers such as keel strips, either will work, but epoxy is
more abrasion resistant.