Catamaran
A Catamaran is a vessel with two parallel hulls of equal size joined by a deck or structure, as opposed to a conventional single-hull (monohull) ship. The wide, twin-hull form gives a catamaran great transverse stability, a large deck area, and shallow draft, and lets it achieve high speed for relatively low resistance.
These qualities make catamarans popular as fast passenger and vehicle ferries, crew-transfer and offshore-wind support vessels, sailing and leisure craft, and workboats — a fast ferry catamaran can carry hundreds of passengers and cars at high speed. The related three-hull form is the trimaran. Catamarans and other multihulls are a distinct and growing class of vessel valued for speed, stability and deck space, alongside traditional monohull ships.
Two hulls give a catamaran stability, deck space, shallow draft and speed that a monohull can't easily match — which is why fast ferries, wind-farm crew vessels and leisure craft increasingly use the form. Multihulls are a distinct, growing class worth understanding alongside conventional ships.
What are the advantages of a catamaran?
Great stability, a large deck area, shallow draft and high speed for low resistance, thanks to its two parallel hulls.
What is a trimaran?
A related multihull with three hulls — a main hull and two smaller outriggers.