Outhauls

Outhauls are control lines used to tension the foot of a sail along the boom, most commonly on the mainsail. The line runs from the sail’s clew, along the foot to a control point on the end of the boom—typically a block or fairlead—and then aft to a winch, cam cleat, or cleat on the boom. By adjusting the outhaul, the sailor changes the sail’s shape, affecting draft, fullness, and performance.

The primary purpose of an outhaul is to control sail shape under different wind conditions and points of sail. In lighter winds, easing the outhaul increases fullness along the foot, enhancing power. In stronger winds or when sailing higher angles, hauling the outhaul tight flattens the sail, reducing draft and improving upwind efficiency. The exact effect depends on sail cut, rig, and the boat’s configuration.

Outhaul systems vary in complexity. A simple setup uses a single line with a block at the boom end and a winch or cleat for tension. Racing rigs often employ a multi-part or purchase-based arrangement (two-to-one or four-to-one) to provide greater mechanical advantage and finer control. Some installations route the line through additional blocks or fairleads to optimize trim and reduce friction.

Proper adjustment contributes to overall sail trim in conjunction with halyards, sheets, and downhauls. Excessively tight outhauls can crease the foot or distort the sail’s shape, while an overly slack outhaul can leave the sail too full for the given conditions.

Outhauls are common on mainsails across many rig types and are adapted for certain headsails or gaff rigs to influence foot tension and performance.