Two hulls fully cored (no need for thick solid glass at the keels) with freeboard higher than yours, a 15'x20' cored bridgedeck, a 15'x10' cockpit fully cored, a fully cored 30'x23' deck containing a large cored deckhouse, a substantial miscellaneous amount of cored deck completing the forward and stern parts of the hulls not connected by decking, all cored furnishings, soles and bulkheads to fit a 42x23' platform (in two hulls, so double the number of furnishings, bulkheads and soles of a single hull) - and you don't think that is much more core than yours? I can easily see it being double the amount.

Mark