Kathy, if epoxy was used by a previous owner while installing or repairing a roof vent opening, around the edges, etc, then note:
Epoxy is frequently used to modify or repair molded
fiberglass structures and surfaces that were originally fabricated with polyester resin,
fiberglass and gel coat. If done right, the epoxy will be stronger than the original
fiberglass. Similar to polyester resin based fiberglass, the epoxy modification or repair can be removed using a grinding flap disc or blade or bit, or a power sander using coarse sandpaper.