A vessel with a narrow hull and large outriggers or floats giving the appearance of a three-hulled craft. The design gives great stability, thus permitting a large sail area which produces relatively high speed. It is mainly used for yachts.
A trimaran is a multihull boat consisting of a main hull (vaka) and two smaller outrigger hulls (amas), attached to the main hull with lateral struts (akas).
History
The first trimarans were built by indigenous Polynesians almost 4,000 years ago, and much of the current terminology is inherited from them. Modern recreational trimarans are rooted in the same homebuilt tradition as other multihulls, though there are a number of production models now on the market, such as the folding, trailerable trimarans from Corsair Marine, Quorning Boats, Performance Cruising Inc., and Ian Farrier, see also the new, 2005, fully Carbon autoclave build SeaCart 30 .
The Trimaran design is also becoming more widespread as a passenger ferry. In October 2005, the U.S. Navy commissioned for evaluation the construction of a General Dynamics Littoral Combat Ship (LCS) trimaran data page designed and built by Austal.
Construction
Trimarans have a number of advantages over comparable monohulls (conventional, single-hulled sailboats). Given two boats of the same length, the trimaran has a shallower draft, a wider beam, less hull area, and is able to fly more sail area. In addition, because of the wide beam, trimarans do not need the weighted keel required in monohulls.
As the righting moment (the force that resists the opposite torque of the wind on the sails) is produced by a float on either side called an ama and not a heavy protruding keel, trimarans are lighter and faster than a monohull of equivalent length. Most trimarans are nearly impossible to flip sideways given a reasonable degree of caution, however, trimarans can reach speeds so great in a storm that they can plow into a wave and flip end-over-end.
The father of the modern sailing Trimaran is Victor Tchetchet a Russian émigré was a strong proponent of multihull sailing.
Safety
Overall, trimarans are considered safer than a monohull as the lack of a heavy keel, combined with the two (usually sealed) amas makes for a nearly unsinkable boat. Because of their stability and safety, trimarans such as the Challenger class have become popular with sailors who have restricted mobility.
Potential buyers of trimarans should look for one that is designed with amas with multiple sealed partitions, controls that all run to the cockpit, a collision bulkhead, partial or full cockpit coverings or windshields, and drain holes in the cockpit that can adequately drain the cockpit quickly, among other things.
World Record
The British sailor Ellen McArthur set a new world record for solo circumnavigation of the world in her trimaran B&Q/Castorama, arriving in February 2005 after just over 71 days at sea.
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