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A catamaran ("cat" for short) is a multihulled watercraft consisting of two parallel hulls of equal size. A catamaran is geometry-stabilized, that is, it derives its stability from its wide beam, rather than having a ballasted keel like a monohull. Being ballast-free and lighter than a monohull, a catamaran can have a very shallow draught. The two hulls will be much finer than a monohull's, the reduced drag allowing faster speeds in some conditions, although the high wetted surface area is detrimental in lower wind speeds. A sailing multihull will heel much less than a sailing monohull of the same length, so on a windward course its sails spill less wind and are more efficient. The limited heeling means the ride may be more comfortable for passengers and crew, although catamarans can exhibit an unsettling "hobby-horse" motion and have a violent unsettling diagonal pitching motion that is unpredictable and makes moving around hard in rougher conditions; the noise is also much more than a monohull experiences. A catamaran's two hulls are joined by some structure, the most basic being a frame, formed of akas. More sophisticated catamarans combine accommodation into the bridging superstructure. Catamarans may be driven by sail and/or engine. Originally catamarans were small yachts, but now some ships and ferries have adopted this hull layout because it allows increased speed, stability and comfort. Although the catamaran configuration was not used for Western vessels until recently, it has long been use by the Tamil people, in Tamil Nadu, South India. Catamarans were developed independently in Oceania, where Polynesian catamarans and outrigger canoes allowed seafaring Polynesians to voyage to the remotest Pacific islands. In recreational sailing, catamarans and trimarans initially met some skepticism from Western sailors versed in traditional ballasted monohull designs. ==Multihull component terms== The word ''catamaran'' is derived from the Tamil word ''kaṭṭumaram'' (கட்டுமரம்), literally "tied wood" (from ''kaṭṭu'' "to tie" and ''maram'' "wood, tree").〔 〕〔 〕 A "kattumaram", a geometry-stabilized rowboat used by the Tamil people ancient TAMIL NADU, shares component part-names with the proa, a multihull sailboat used by the Oceanic people. Although the original "kattumaram" included a monohull raft, the modern word ''catamaran'' exclusively means a twin-hulled vessel. In the United States, there are three terms that describe the main components of catamarans and trimarans, namely: "vaka", "aka", and "ama",〔(【引用サイトリンク】title=The Tridarka Raider )〕 terms derived from the Malay and Micronesian language group terms for parts of the outrigger canoe. These terms, which reflect only American usage, are unknown in the UK, where English words are used instead. *Vaka – the canoe or main hull〔 〕 *Aka – the framework member that connects the ''vaka'' (hull) to the ''ama'' (outrigger, or “float”)〔 *Ama – the outrigger, connected to the ''vaka'' by an ''aka''〔 In Hawaiian, the main difference is the main hull or canoe is a ''wa'a'' pronounced like ''va ah''. There is no plural in Hawaiian and so a double canoe, or two canoes joined together by ''aka'' is a ''wa'a wa'a''. An area in lower Puna is called ''wa'a wa'a''. A comprehensive list of Hawaiian words for a boat is published by the Polynesian Voyaging Society. For a craft with more than two hulls, ''"cata-"'' is replaced with the Greek numerical prefix for the number of hulls (e.g. trimaran, pentamaran). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「catamaran」の詳細全文を読む スポンサード リンク
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