I have fiberglass integral fuel tanks in my Ingrid 38. Many other Ingrid's
were build with fuel and water tanks of fiberglass. (My water tanks are also
integral and are coated with gelcoat.)

Since the hull is polyester resin as well as the tank tops, I had some
concern regarding etching or leaching of the resin. This concern was stemmed
from some warning from a diesel manufacture about micoscopic glass fibers
reaching diesel injector pumps. I raise this concern with my fiberglass
supplier, Tacoma Fiberglass. They contacted some fiberglass resin chemist
and provided a recommendation to coat the interior with an epoxy product.
The material I used contained some graphite which, I have found makes for a
very slick surface that is basically self-cleaning. I have yet, in 3 year,
to find any film build up.

--
My experience and opinion, FWIW
--
Steve
s/v Good Intentions