GRP Layer Composition / Mounting Hardware

[globetrot]

I have scoured the forum and, perhaps I missed it, can't find information on the actual layer composition of the GRP deck on a BR20. Specifically, can anyone clarify the layer composition of the aft deck above the transom, on both sides of the mizzen mast? What is the core composition?

I am mounting a ladder in this area, and when drilling the pilot holes, I distinctly felt the drill bit go through at least two layers. I could also see two types of drill cuttings around the borehole. I assume there is a more rigid GRP exterior and a structural core.

Of course, I could always take the easy route and use a silicone sealant to coat the bolt and the underside of the hardware. But this is not the best way if there is a core that could absorb water. If the core can absorb water (even a little), I will drill the holes a bit larger than needed, fill them with epoxy to create a water-tight seal, let it cure, and then re-drill the holes for the actual bolts and use sealant.

[Llafurio]

As far as I can remember there is no water absorbing core like foam or balsawood. Of course, there is the outer cream colour gelcoat surface, and underneath the blue-green-grey GRP. In any case, when bolting something onto the deck, I recommend a spot of sealant/adhesive on the contact area surrounding the hole. not just for sealing but also for fastening against pulling forces.

BTW, there was a generation of "GRE" BRs, Glass Reinforced Epoxy. They had a hull of reinforced epoxy resin with a foam core, but then also a normal solid GRP cockpit and deck.
C.