These are some of the few true watertight deck plates, at a reasonable price. They do stand "proud" of the surface. The surface around the rim should be smooth, and one of the issues for the C Dory cockpit deck, might be the thickness of the deck. Generally I have seen them used for decks which are no more than 3/8" of an inch thick--often aluminum or solid fiberglass decking. The cockpit deck is over 3/4" thick. One could undercut, about the diameter or even 2 sectors, of the dimension of the backing bar, and then re-laminate that specific area to about 1/4" thickness, so the pressure of the backer could be used.