Outhaul

An outhaul is a control line found on a sailboat. It is an element of the running rigging, used to attach the mainsail clew to the boom and tensions the foot of the sail. It commonly uses a block at the boom end and a cleat on the boom, closer to the mast, to secure the line.^[1][2]

The outhaul on a US Yachts US 22 sailboat. This design uses a braided steel cable, with a swaged thimble and clevis to attach to the sail clew grommet.

The outhaul is loosened to provide a fuller camber or tightened to give the sail foot a flatter camber. Depending on the wind, this will increase or decrease boat speed.^[3]

Sailboat designer and sailing theorist, Frank Bethwaite, recommended that the outhaul, along with the other sail controls on a racing sailboat, should be knotted and the boom marked with the settings for different wind speeds.^[4]