Multihull

A watercraft with two or more parallel hulls. Catamarans have two hulls, while trimarans have three.

Catamaran: A watercraft with two parallel hulls joined by a deck or framework. The two-hull arrangement is the most common multihull configuration.
Initial stability: A vessel’s resistance to small angles of heel or tilt. The wide spacing between hulls gives many multihulls strong resistance to small tilts.
High-speed craft: Vessels designed to operate at high speeds relative to their size. Multihulls are used when slender hulls and broad decks suit fast operation.
Monohull: A watercraft whose buoyancy is provided by a single main hull. It contrasts with multihulls in hull count, beam, stability, and available interior volume.
Trimaran: A watercraft with a central hull and two smaller outrigger hulls. Its central hull and outriggers create a three-hull multihull layout.
Righting moment: The torque that tends to return a tilted vessel toward upright. Hull spacing creates leverage that resists or corrects multihull heeling.
Ferry: A vessel that carries passengers, vehicles, or goods on a regular route. Catamaran ferries use separated hulls for speed and a broad passenger deck.
Outrigger canoe: A canoe stabilized by one or more lateral floats connected to its main hull. It shares the multihull principle but commonly uses a narrow canoe and smaller stabilizing float.
Ama: An outrigger hull positioned beside a vessel’s main hull. A trimaran’s side hulls are amas, stabilizing the central hull.
Hull speed: A traditional estimate of the speed at which a displacement hull’s wave-making resistance rises sharply. Narrow multihull hulls can reduce the wave-making limits associated with conventional hull speed.

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