Helped build a 39' custom a few years back. Owner put a granite countertop next to the stove for hot pots. It's the same stuff the Lear jet folks use, about 1/4" of granite over an aluminum honeycomb. When he gets accused of having a go-fast racing machine, he just points out the granite countertop. Launch weight of the boat was 13,000# (with the granite) - of that, 6800# is keel, 7' draft. He has a 10' draft offshore keel designed that keeps the same stability but reduces displacement by 2000#.