Frank, A frp sailboat should gradually get thicker from the sheer on down. 338 is not much more than 1/8" at the seam. But seemingly only getting to 3/8" down in the keel. That is what is so disconcerting, 338 seems to be very conservatively layered, if you can call it that. Even the transom is barely 5/16 in the center, fattening out in the corners and the tabbing across the top.
The hull/deck seam is thickened by the mat tabbing. (On 338 the toerail molding is now filled flush to the inside of the deck.) A test hole thru the topside in a chainplate area yeilded 3/16"
There is considerable factory tabbing of the cabin decks, bulkheads, settees, stringers, although the tabs seldom go further than 4-5" from a joint, which may accouint for varying thicknesses of the hull in proximity. The old cockpit drain holes showed the hull to be around 3/8s.
I feel a little better that the keel cavity is filled with epoxy and there is now a built-in watertite tank running the length of the cabin over the ballast in the turn of the bilge. 338's (supposedly) lightly built hull will have all its furniture tabbed in and probably a layer of 20oz xmatt (about 1/16" thickness) most areas below the waterline. Insurance???
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Maybe somebody knows just how hard or sharp coral calcium is? Probably harder and sharper in the tropics! What will it do to the hull of an A/C? Has anybody seriously run onto rocks? What damage occured? Pictures? More than curious, would like to hear and see what the A/C hull can take!!!