Mast aft rig

A mast aft rig, alternately referred to as aft-mast rig, is a sailboat sail-plan that uses a single mast set in the aft half of the hull. The mast supports fore-sails that may consist of a single jib multiple staysails, or a crab claw sail. The mainsail is either small or completely absent. Mast aft rigs are uncommon, but are found on a few custom, and production sailboats.

Many mast-aft rigs utilize a small mainsail and multiple staysails that can resemble some cutter rigs. A cutter is a single masted vessel, differentiated from a sloop either by the number of staysails, with a sloop having one and a cutter more than one, or by the position of the mast, with a cutter's mast being located between 50% and 70% of the way from the aft to the front of the sailplan, and a sloop's mast being located forward of the 70% mark. A mast aft rig could, based on headsail count, be considered a variation of the sloop or cutter, or, based on mast position, a unique rig.

In the typical Bermuda rig, the sails located in front of the mast generally deliver a higher percentage of the driving force. The stay that supports the leading edge of the sail causes far less turbulence than a mast, resulting in better airflow across the lee side of the sail. To take advantage of this fact, Bermuda rigs are shifting towards larger fore-sails and smaller mainsails. Fore-sails include jibs, genoas and staysails. The cutter, with its use of multiple foresails, achieves the same goal of placing a higher percentage of the sail area in staysails.

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