A reefing pennant (or pendant) is a strong line used in sailboat rigging to pull the reefing cringle (a reinforced hole) on the leech of the mainsail down to the boom. By hauling this line tight, the sail is secured at a lower point, reducing the sail's surface area for improved stability in high winds.

Key Aspects of a Reefing Pennant:
Purpose: It replaces the job of the main sheet/outhaul by pulling the leech down and back, maintaining sail shape and tension when shortened.

System Usage: In slab/jiffy reefing, each reef point has a dedicated pennant running from the boom, through the cringle, and often back to the cockpit.

Securing: The line is often made off with a timber hitch or passed through blocks and back to a winch/clutch for adjustment.

Alternatives: While the pennant handles the aft corner (leech), the forward corner (tack) is secured via a hook or a separate line at the gooseneck.

Reefing is critical when the wind increases to keep the boat "on its feet".