GRP/Fibreglass info needed

[mekanik]

What is the substrate and the application ?
If substrate is fairly substantial the plate could be drilled and countersunk to take woodscrews, edges of plate need a good chamfer possibly 30 deg so that you can get a decent layup when bonding the cover layers of glass(will prevent air pockets you might get with 90 deg interface). bond the plate to existing fiberglass using your epoxy and screw it to substrate, then apply your epoxy and glass to cover the assembly.

[Neale]

This is the kind of thing that boat-builders are doing all the time, but I can't think of case where I've ever seen a plate embedded in laminate. For one thing, polyester resin isn't a very good adhesive so it won't bond to the plate - I suppose that you could put holes in so that the laminate is bonded through the plate, or use an epoxy laminate? Fixings to take rigging loads on a GRP boat would generally be through-bolted and use a sealant like Sikaflex which would give a good working life and if properly made, guaranteed waterproof.