Multihulls

Multihulls are boats or ships that use more than one hull. The most common forms are catamarans, which have two parallel hulls, and trimarans, which have three hulls. A proa is another form, typically with an outrigger and an asymmetric, shifting navigation orientation. Multihulls differ from monohulls in their geometry, stability, and hydrodynamics.

In design terms, the wide beam of catamarans and trimarans provides high initial stability, a large deck area, and the ability to carry substantial payloads. Because the hulls can be slender and lighter per length, multihulls often experience lower total hull drag and higher speed potential, especially when planing or using hydrofoils. Stability is dynamic and depends on hull configuration and sea state; these vessels can behave differently from monohulls in gusty conditions and may require careful handling. Modern racing versions frequently employ large rigs, twin rudders, and sometimes hydrofoils or other appendages to optimize performance.

Construction commonly uses fiberglass or other composites and aluminum, with interiors arranged to maximize the wide beam. Cruising catamarans emphasize comfortable living spaces and easy water access, while trimarans focus on lightweight construction and stability to support fast cruising.

Uses include recreational sailing yachts, racing boats, passenger ferries, and cargo operations. Multihulls have been prominent in fast sailing events and around-the-world races since the mid-20th century, driving developments in materials, rigging, and hull design. Their combination of speed, deck space, and payload makes them a distinctive family of boats throughout maritime history.