multihull

thumb|150px|The relationship between monohulls & multihulls

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 (with two hulls), and trimarans (with three hulls). There are other types, with four or more hulls, but such examples are very rare and tend to be specialised for particular functions.