Sprit

The spritsail is a four-sided, fore-and-aft sail that is supported at its highest points by the mast and a diagonally running spar known as the sprit. The foot of the sail can be stretched by a boom or held loose-footed just by its sheets. A spritsail has four corners: the throat, peak, clew, and tack. The Spritsail can also be used to describe a rig that uses a spritsail.

Historically, spritsails were the first fore-and-aft rigs, appearing in Greco-Roman navigation in the 2nd century BC.

The luff of the sail is bound to the mast, but unlike the gaff rig where the head is bound to a spar, this rig supports the leech of the sail by means of a diagonal spar or spars named a sprit. The forward end of the sprit spar is attached to the mast, with the after end of the sprit spar attached to the peak. The sprit is steadied and controlled from the deck by a pair of wire vangs attached to the peak of the sail. It is said to be the ancestor from which the common gaff rig evolved in 16th-century Holland. The foot of the sail may be bent to a boom, or be loose-footed and just controlled by its sheets.

The spritsail was best known from its use in the Thames sailing barge, which employs two similarly sized spars to form the framework for the sail area. In a barge, the mast is stepped vertically in a , whilst the sprit is suspended by chain stanliffs from the mast head at an angle of about 30° from vertical, with sprit to the starboard side of the mast. The heel of the sprit is secured to the mast, by the muzzle, which allows the sprit is free to move laterally, nearly as far to each side as the shrouds. This enables the vessel to reach and run. The instability caused by allowing such a weighty spar to extend too far away from the vessel's centreline, however, had to be borne in mind when designing hull and rigging. The peak of the sail is permanently attached to the head of the sprit, which is steadied by two sets of vangs.

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