The top bolt goes through
the sail tack cringle and the bottom one holds the gooseneck onto the mast.Remove the top bolt through the sail. Buy a reefing hook at your local chandlery. The thickness of the new hook may require a longer bolt. Replace the bolt, washer and the nut with the reefing hook. You can install one on each side for two reef points.Reefing hooks can be found in any boating catalog, try West marine online, too. They consist of a piece of steel rod bent with a loop for the bolt and a bend for the hook.In lieu of that, use line reefing so you don't have to go to the mast to reef. That's explained in the C30 manuals on the C30 Association website at www.catalina30.com