A trimaran is a multihull boat that comprises a main hull and two smaller outrigger hulls which are attached to the main hull with lateral beams. Most modern trimarans are sailing yachts designed for recreation or racing; others are ferries or warships. They originated from the traditional double-outrigger hulls of the Austronesian cultures of Maritime Southeast Asia; particularly in the Philippines and Eastern Indonesia, where it remains the dominant hull design of traditional fishing boats. Double-outriggers are derived from the older catamaran and single-outrigger boat designs.
USA-17—a 90-foot-long (27 m) trimaran, type BOR90.
A traditional paraw double-outrigger sailboat (bangka) from the Philippines
An Iranun lanong, a double-outrigger warship from the Philippines used in the navies of the Sultanates of Maguindanao and Sulu from the 18th to late 19th centuries. They were also commonly used for raids and piracy.
The Balatik, a paraw, a functioning replica of a traditional Austronesian sailing trimaran from the Visayas Islands of the Philippines
A multihull is a boat or ship with more than one hull, whereas a vessel with a single hull is a monohull. The most common multihulls are catamarans, and trimarans. There are other types, with four or more hulls, but such examples are very rare and tend to be specialised for particular functions.
A Polynesian catamaran
Model of a wa, a single-outrigger vessel, from Woleai in the National Museum of Ethnology (Japan)
A 60' trimaran with high aspect fractional Bermuda rig
A catamaran ferry in Salem, Massachusetts
