A multihull is a ship, vessel, craft or boat with more than one hull. Multihull ships (vessels, craft, boats) include multiple types, sizes and applications. Hulls range from two to five, of uniform or diverse types and arrangements Catamarans are the most common type, with two symmetric hulls. They are used as racing, sailing, tourist and fishing boats. About 70% of fast passenger and car-passenger ferries are catamarans. About 300 semi-submersible drilling and auxiliary platforms operate at sea.