I put my two cents into this in the Ask Bud section.
But again, Westsail always used a foam fillet on the edge of the three main structural bulkheads. It is not necessary for the furniture bulkheads because they do not go across the hull.. An angular filet between the plywood face and the hull on the rest of the bulkheads is good so the fiberglass lays in well and is easier to wet out with resin.