can be any where, pay strict attention to all structural angles 90 and 45 degree etc, look at any and all stress cracks and thru-hull fittings and around areas where screws have been placed to hold the rigging, look for bulges and bubbles, pound the surfaces with a rubber or hard plastic hammer, listen for hollow sounds, the balsa coring can soak up water and moisture, then delaminates over time if penetrated. and good luck !