Re: stringers
If your riding in boat try to listen to the hull for any rattling, or feel any vibration's when coming down off a wave, solid boat should have a nice clean thud when landing hard, also if boat has a walkthru windscreen, pay attention to the alignment from on side to the other and that the center portion closes and fits correctly. Check hull bottom for any signs of cracks along any strakes and or chines, this could be a good indication of a broken of rotted stringer also, but sometime's there is no way of knowing.