This is a tricky question. Fiberglass is a man-made material and like plastic, each manufacturer uses a different formula.  This will be a trial and error application.  I recommend roughing up, or sanding the surface of the fiberglass first, to give the glue something to adhere to; then follow the standard directions.

Something else to consider would be Gorilla Tape for a temporary fix, however, you would want to check the tape occasionally since it will breakdown over time when exposed to the sun and rain.

The Gorilla