I recently was given a 1975 O'Day Javelin that had been sitting on a trailer in a woods for several years. I put in a new transom drain plug before putting it in the water, but water came rushing up thru the drain opening in the cockpit area near the back of the boat. That plug was not in at the time. There don't appear to be any cracks in the hull. Are there other areas where it could be leaking heavily? Does water come in thru the center board area? Plz help!