Example of weight differences for some of cut panel parts
on Grainger Barefoot 45.
lower hull side foam 51kg balsa 68kg - 33% diff in weight of core
upperside hull foam 106kg balsa 141kg - 33% diff
It doesn't mean foam vessel is 33% heavier. presuming resin, tapes etc the balsa core alone is 33% heavier than foam core for that particular vessel.