White Dolphin has a 10" memory foam mattress in the v-berth that the PO installed. Its basically a Sams Club mattress that he cut to fit.
It is kind of ridiculous: outrageously heavy but also outrageously comfortable.
We remove it for racing which is a giant pain in the butt (you should hear the crew complain), but it makes our non-racing weekends in Charleston very enjoyable.