Twin-hull ship

A catamaran (/ˌkætəməˈræn/) (informally, a "cat") is a multi-hulled watercraft featuring two parallel hulls of equal size. It is a geometry-stabilized craft, deriving its stability from its wide beam, rather than from a ballasted keel as with a monohull sailboat. Being ballast-free and therefore lighter than a monohull, catamarans often have a shallower draft (draught) than comparably-sized monohulls. The two hulls combined also often have a smaller hydrodynamic resistance than comparable monohulls, requiring less propulsive power from either sails or motors. The catamaran's wider stance on the water can reduce both heeling and wave-induced motion, as compared with a monohull, and can give reduced wakes.

Catamarans range in size from small (sailing or rowing vessels) to large (naval ships and car ferries). The structure connecting a catamaran's two hulls ranges from a simple frame strung with webbing to support the crew to a bridging superstructure incorporating extensive cabin and/or cargo space.

Catamarans from Polynesia and Maritime Southeast Asia became the inspiration for modern catamarans.

Catamaran-type vessels were first developed as early as 1500 BCE by the Polynesian peoples. These early examples were likely related to outrigger canoes and consisted of two canoes bound together with a wooden frame, sometimes accompanied by a sail. Despite their simplicity they were nonetheless effective, allowing seafaring Polynesians to voyage to distant Pacific islands.

Catamarans were seldom constructed in the West before the 19th century, but they were in wide use as early as the 5th century by the Tamil people of Tamil Nadu, South India. The word "catamaran" is derived from the Tamil word, kattumaram, which means "logs bound together." The 17th-century English adventurer and privateer William Dampier encountered the Tamil people of southeastern India during his first circumnavigation of the globe. He was the first to write in English about the primitive watercraft he observed in use there. In his 1697 account of his trip, A New Voyage Round the World, he wrote,

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