Ply construction - Interior finishing.

Hi guys!

I’m building a self-designed 26ft sailing catamaran. Construction is good quality exterior grade 6mm ply over solid frames/bulkheads and adequately spaced stringers.

The exterior will be glassed with bi-axle and epoxy resin and interior joints filleted with epoxy and glass tape. However, I’m a bit uncertain about the interior. I’m not going for a natural wood finish and will probably paint the interior.

Question: To effectively seal the interior, should I use something like a polyester resin or a good quality primer and then a couple of coates of paint. Your input, as always, is highly valued.

Thanks lads!

 

The fact that you already using epoxy on the exterior lamination and the taping of the joints inside leads to using epoxy to seal and protect the whole interior surface. Use the same resin as for the lamination but try to obtain a compatible viscosity reducing compound (not solvent based) to add which allows greater penetration into the timber fibres. Lightly sand then use a second coat of epoxy at normal strength. Lightly sand again and use a high build polyurethane one pot undercoat. Sand until fairly smooth and paint with one pot polyurethane gloss paint until you get satisfactory coverage, probably two coats. This treatment should last almost indefinitely for an interior.

 

i vote for using high build epoxy primer and then a polky 2 pack over the top worked for me, also why biaxial? surely you are just using the external glass for waterproofing as your ply should have plenty of strength already if you are wanting strength from the biax then you should glass the inside as well
sean