Someone else can give the definitive answer but, 1) don't use silicone, whatever you use, 2) those are probably bronze screws, not brass, 3) if the screws are penetrating the fiberglass at all, I'd at least seal around the screws. I'd use butyl tape.
2000 Beneteau 331
Northern Chesapeake Bay
Ambition is a poor excuse for not having enough sense to be lazy ~ Steven Wright