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.

[1][2] 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.

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.