Transom side of empty hole. What you are seeing is the balsa core of the transom, followed by the forward fiberglass skin of the transom, and then the (white) filler that fills the gap between the splashwell molding and the forward transom skin.
Transom side of empty hole. What you are seeing is the balsa core of the transom, followed by the forward fiberglass skin of the transom, and then the (white) filler that fills the gap between the splashwell molding and the forward transom skin.