Re: looking for information on hulls
One of the reasons that the less expensive mass market boats have not cored hulls is because they are more expensive to build. The current First 40 had initially a cored hull then they called it CR in a more basic version, lowered the price and made it with a monolithic hull. They don't advertise but they make more expensive cored versions if someone wants a more fast and rigid boat, mostly for racing.
Dehler, for instance on the new 41 offers only cored boat: with a balsa core in the cheaper version and on the more expensive an epoxy boat with airex core.
All Salonas (as many other brands) are cored boats but on the areas of the hull that will slam they use monolithic. To my knowledge all cored boats have monolithic fiberglass in all zones of the hull that have through the hull passages.
A hull of an old cored boat should be checked with a lot of care. Any water infiltration in one point will spread to a large area and with time it will give origin to delamination.
Cored hulls are not only lighter but more rigid and resistant than monolithic hulls, except probably in what concerns impacts with rocks or containers were a monolithic hull, if strong, will have an advantage.