Bill, The stop pin is easily seen inside the centerboard slot when viewed from below. It is located about 1" forward of the aft end of the slot and about 1" up from the bottom (or about 5" forward of the lowest aft point of the keel). The ends of the pin are also vaguely visible as depressions or irregularities in the outside surface of the keel. By the way, magnetic devices won't detect stainless steel. Mark Dvorscak