In the green area (2 carriage bolt fasteners) is a wood filler, no sealant or calking. The plate in the area of the next 2 fasteners is against the hull, with no sealant or calking behind it. The last fastener (the bottom one) has a backing of a small amount of sealant behind it. The sealant in that area extends just a short distance above the bolt and acts like a pad for the plate to sit on. The hull is solid FRP and the fasteners go through and are sealed on the inside. As far as I can tell, the plates can "breath" on the backside, I just can't see it.

Greg