A fore-and-aft rig is a sailing vessel rig with sails set mainly along the line of the keel, rather than perpendicular to it as on a square rigged vessel.[2]
The fore-and-aft rig is believed to have been first developed independently by the Austronesian peoples some time around 1500 BC with the invention of the crab claw sail. It is suggested that it evolved from a more primitive V-shaped "square" sail with two spars that come together at the hull. Crab claw sails spread from Maritime Southeast Asia to Micronesia, Island Melanesia, Polynesia, and Madagascar via the Austronesian migrations.[3] Austronesians in Southeast Asia also later developed other types of fore-and-aft sails, such as the tanja sail (also known as the canted square sail, canted rectangular sail, or the balance lug sail).[3]
The square rig had predominated in Europe since the dawn of sea travel, but in the generally gentle climate of southern Europe and the Mediterranean Sea during the last few centuries before the Renaissance the fore-and-aft began to replace it. By 1475, its use increased, and within a hundred years the fore-and-aft rig was in common use on rivers and in estuaries in Britain, northern France, and the Low Countries, though the square rig remained standard for the harsher conditions of the open North Sea as well as for trans-Atlantic sailing.
The triangular lateen sail was more maneuverable and speedier, while the square rig was labor-intense but seaworthy.