Are you looking at buying a boat that is Airex cored or are you planning on building one. If buying it will depend on the specific manufacturer and how it was done. If building that is a different issue and there are many options including balsa which is stronger and not subject to heat deformation which the foam cores exhibit in a warm climate. The link I provided gives a good explanation of modern cores and shows test results of same. Here's a link to a discussion on Boat Design Forum about Airex vs others.
Airex and any foam based hull materials - Boat Design Forums