Spritsail

The spritsail is a form of three or four-sided, fore-aft sail and its rig. Unlike the gaff where the head hangs from a spar along its edge, 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 but bisects the face of the sail, with the after end of the sprit spar attaching to the peak and/or the clew of the sail. It is said to be the ancestor from which the common gaff rig evolved in 16th-century Holland. Historically, spritsails were the first fore-and-aft rigs, appearing in Greco-Roman navigation in the 2nd century BC.

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 from the mast at an angle of about 30° from vertical, near the mast's foot, with the foot of the sprit to the starboard side of the mast, in a kind of basket, called a muzzle. 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.

The spritsail rig was normally used without a boom. (The latter was usually found on fore-and-aft rigged vessels to keep the mainsail in an aerodynamically efficient shape.) Such loose-footed sails can also be found on the Norfolk wherry and the bawley class of vessels and was a feature of the Cromster. In this last example, the ability to furl the foot of the sail cleared the deck of the sheet while the sail could still be controlled by the vangs. This made gunnery much more readily possible.

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