South Shore, The Sisu hulls are balsa cored to the keel, so make sure to check all thu-hull fittings for moisture, proper de-coring, and no de-lamination. the bulkhead is also cored and so is the lobster top, so be sure to check them as well. If you take a look at my photo album in my user profile you can see the balsa core removal. everything I've done to the hull is up in that gallery. Good Luck.