GRP Repairs - Some Helpful Tips
Firstly confirm the extent of the damage, it may be necessary to remove deck hardwear to gain full access. Ensure correct personal protective equipment is worn when carrying out repairs.
Surface (Gelcoat) Damage only
Where not extended through the gelcoat into the laminate, for cracks v-out the crack. Otherwise remove loose gelcoat and chamfer edges. Clean with acetone or styrene then fill with colour-matched gelcoat paste, letting it bulge slightly. When it begins to cure seal the surface with plastic or PVA. Fair and polish when cured.
For deck voids, break away the cracked gelcoat then use a rotary grinding point to grind the interior surface of the cavity. Chamfer the gelcoat edges. Clean with acetone or wipe with styrene (better), fill cavity with a putty of polyester (laminating not epoxy) resin and chopped glass. When hard, fill with gelcoat, overfilling slightly. Roll a piece of plastic into the repair and seal edges with tape. Sand flush and buff when cured.
Shallow gouge - use a scraper to open up the damage putting a smooth chamfer on each side of the gouge. Wipe the V with styrene to reactivate the surface then fill the V with polyester resin thickened with chopped glass. When the resin kicks fill the remaining depression with colour-matched gelcoat paste, letting it bulge slightly. When it begins to gel seal it with plastic or a coat of PVA. Fair and polish when cured.
Deep gouge (deeper than upper two or three layers) - grind the damaged area into a depression with a 12-1 chamfer. Wipe with styrene and coat with polyester resin. Position and wet out increasingly large areas alternating mat (first layer) and cloth to the bottom of the gelcoat layer. When resin kicks brush on (or spray) 500 microns gelcoat paste. Fair and polish when cured. Consider applying additional laminate on the inside with epoxy to provide further strength.