Most production boats built after 1970 have balsa core sandwiched in their deck structure. Balsa is a great engineering material providing a light and strong panel. However, when water migrates into the core, usually from improperly bedded hardware, the effects can be disastrous. Most times the repairs are done from the top surface of the deck due to liners, bulkheads and lockers that obstruct access underneath. On this particular job though, with nothing in the way, we were able to cut away the fiberglass from the effected area and excavate the wet balsa from underneath. With the help of a vacuum bag we were able to install new core and bottom skin while leaving the nonskid surface of the cabin top untouched.