Red dashed line indicates up position; blue, down position. Downswing is controlled by a tang protruding aft and attached at the upperleftmost corner of the red outline. In the full down position, tang rests atop a stop pin through the keel to allow freeswing in shallow depths or over obstructions. Two schools of thought seem to exist. Officially, the centerboard should rest against the stop pin when fully extended. Others feel this puts undue stress on the stop pin, which then fails. They retract the CB back up a few inches from full down position to put the CB weight on the pendant, which is more easily (or at least cheaply) replaced, using the stop pin as a fail-safe. The debate rages on. Note pendant attachment (blue line to winch at cockpit sole.)