My triton slaps fairly loudly... not terrible unless you get stuck under the cockpit
I'm wondering, since the noise
is being transfered through the fiberglass
... and not from the outside and down the hatch
(At least on my boat) if this isn't a place where energy absorbing mat could come in handy? On cars there are various audiophile grade insulators that take sound energy and turn them into heat, instead of just adding mass to the panel. In addition to mat, there are spray on rubber mastic products with ceramic balls that dampen sound with very little weight.
Do cored hulls have similar noise
issues, or are they quieter than solid laminate? Steel
boats supposedly have less noise from the many inches of spray foam.