I have repaired fiberglass boats and even fabricated a fiberglass canoe from scratch. Your repair is fairly easy, because you will have access to both sides of the repair. You will need polyester resin, catalyst, fiberglass cloth, body filler, and a grinder or sander as well as some application tools. Start by using the grinder or sander to sand down the surface around the hole. You need to completely sand the outer surface to get a dusty looking finish. There are often vapor suppresants used when new fiberglass products are originally made. These can leave a residue that must be removed to get a good bond.
A new canoe is made in a mold. The smooth outer side is against the mold, which is sprayed with a gelcoat, then laminated with fiberglass and resin. You need to re-create this mold by applying a sheet of fairly rigid plastic over the outside surface of the hole. Coated with wax (release agent) this is your mold. You can then laminate from the inside by applying fibergalss strips saturated with catalyzed resin. Be sure to roll out all air bubbles and voids. When the repair has set, remove the piece you used as a mold. Sand the surface and apply more resin and glass if there is a large void, or just use body filler to smooth the surface. This can take several coats to get right. Final step is painting to match.
Depending on your experience, it can be a good investment to just have a body shop or fiberglass repair shop do the work for you, but if cosmetics are not a critical issue, no reason not to DIY.
.
