A trimaran is a multihull boat that comprises a main hull and two smaller outrigger hulls (or "floats") which are attached to the main hull with lateral beams. Trimarans are most commonly sail-driven yachts designed for recreation or racing, but there are a few trimaran ferries and warships.
- 1 History
- 2 Multihull component terms
- 3 Comparison to monohulls
- 4 Safety
- 5 33rd America's Cup
- 6 World records
- 7 In naval ships
- 8 Image gallery sailing trimarans
- 9 Image gallery engine driven trimarans
- 10 See also
- 11 Notes
- 12 References
- 13 External links
The first trimarans were built by indigenous Polynesians and other Pacific islanders almost 4,000 years ago, and some of the current US terminology is derived from them. The name "trimaran" is a 20th-century word concocted from "Tri" and "(Cata)maran". Sailing catamarans and trimarans gained popularity during the 1960s and 1970s. Originally, many catamarans and trimarans were homebuilt, but there are now many production models available. Some trimarans in the 19–36-foot lengths (5.8–11.0 m) are designed as "day-sailers" which can be transported on a road trailer. These include the original Farrier - Corsair folding trimarans - and original John Westell swing-wing folding trimaran (using the same folding system later adopted also on Quorning Dragonfly) and like trimarans. Some designers have penned "demountable trimarans" that are able to be trailered (like the SeaCart 30 by Oceanlake Marine ).
The trimaran concept has been used for both passenger ferries and warships. In 2005 the 127-metre trimaran (417 ft) Benchijigua Express was delivered by Austal to Spanish ferry operator Fred Olsen, S.A. for service in the Canary Islands. Capable of carrying 1,280 passengers and 340 cars, or equivalents, at speeds up to 40 knots, this boat was the longest aluminum ship in the world at the time of delivery. A modern warship, the RV Triton was commissioned by British defence contractor QinetiQ in 2000. In October 2005, the United States Navy commissioned for evaluation the construction of an General Dynamics LCS trimaran designed and built by Austal. The DARPA is experimenting with the trimaran design, and in 2012 awarded SAIC a contract to perform Phases 2 through 4 of the ACTUV Program. The contract is expected to be completed by August 2015.
Multihull component terms
According to American usage, there are three terms that describe the main components of catamarans and trimarans, namely: “vaka”, “aka” and “ama”. These terms come from the Malay and Polynesian language group terms for parts of the outrigger canoe
- Vaka is the canoe or main hull.
- Aka is the framework member that connects the vaka (hull) to the ama (outrigger, or “float”).
- Ama is the outrigger, connected to the vaka by an aka.
(The above terminologies reflects only American usage. In the UK the main hull of a trimaran is called simply the main hull or centre hull. The outrigger hulls are floats. The structures between the main hull and the floats are called the wings and the structural portions thereof are beams).
In cruising trimarans the wings are solid and cabin accommodation extends over them, while in racing trimarans accommodation is limited to the main hull and the wings are open sheets of netting.
Comparison to monohulls
Two types of trimaran exist: the regular trimaran and the open trimaran, which features a trampoline between the hulls instead of plating.
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 wetted area, and is able to fly more sail area. In addition, because of the righting moment provided by the wide beam, trimarans do not need the weighted keel that is required in monohulls.. As a result of the wide beam, the trimaran offers much better straight-line performance than a monohull, is able to sail in shallower water, and maintains its stability in stronger winds. However, its wider beam requires more space to maneuver, so tacking and gybing can be trickier in confined areas. In the case of trimarans with open wings, the narrower hulls provide less living space than an equivalently sized monohull, but with solid wings the cabin accommodation can extend out over the wings providing a very roomy interior. Finally, trimarans require more docking space in marinas, unless the ama can be folded to reduce the beam.
As the righting moment (the force that resists the opposite torque of the wind on the sails) is produced by a float, or ama, rather than a heavy protruding keel, trimarans are lighter and faster than a monohull of equivalent length. A lightweight retractable keel or foil, referred to as a centerboard or Daggerboard is often employed to resist lateral movement, making many models easily beachable. Most trimarans are difficult to flip sideways given a reasonable degree of caution, however, trimarans can reach speeds so great in high winds that they can plow into the back of a wave and flip end-over-end (Pitchpole). This hazard is especially dangerous for a multihull that is using a spinnaker in high winds and large seas. To avoid this unfortunate scenario trimaran sailors are advised to reduce sail and to always have all sails easily released. The use of trampolines with a large weave, to allow water to easily pass through, and the deployment of parachute anchors drogues and sea anchors whenever appropriate should reduce the risk to an acceptable degree.
The father of the modern sailing trimaran is Victor Tchetchet, a Russian émigré and a strong proponent of multihull sailing. Mr. Tchetchet, who was a fighter pilot during the First World War in the Czar's Air Force, lived in Great Neck, New York from the 1940s until his death. He built two trimarans while living in the US, Eggnog 1 and 2. Both boats were made of marine plywood and were about 24 feet long. Mr. Tchetchet is credited with coining the name trimaran. Aside from boat design Mr. Tchetchet earned his living as a landscape and portrait painter. About the same time, Arthur Piver was also building trimarans in the USA and created many early plywood designs to which amateurs built their boats. Many successfully crossed oceans despite being relatively heavy and inferior compared to those of more modern design. The homebuilt cruiser movement survived his death in 1968, with designers Jim Brown, John Marples, Jay Kantola, Chris White, Norman Cross and Richard Newick bringing the trimaran cruiser to new levels of performance and safety.
Several manufacturers build trimarans in which the floats can be folded near to the main hull. This allows them to be trailerable and/or to fit in a normal monohull space in a marina. At least 6 technologies are in use:
- Trimax trimarans use a hightech folding mechanism 
- Weta Trimaran use tubes to connect the floats to the main hull using a canvas trampoline.
- Astusboats use telescopic tubes to connect the floats to the main hull.
- W17 tris use a strong hinge and latch system, that allow the amas to fold over the main hull to reduce width for trailing. Suitable for craft under 18ft only unless waterstays are added.
- Farrier Marine use a vertical folding mechanism, first used on the Trailertri and subsequently on most of his designs. All Farrier designed boats are known as Fboats (F22, F24, F27 etc.).
- Whisper also uses a vertical folding mechanism 
- Corsair Marine trimarans use the vertical folding mechanism designed by Ian Farrier. When Farrier resigned from the company in 2000, the "F" (for Farrier) designation was replaced with a "C" (for Corsair) designation on their trimarans.
- Dragonfly Trimarans use a nearly horizontal articulation called SwingWing. The slight angle makes the floats fold into the narrower, lower part of the central hull and also increases stability when in the folded position. A similar horizontal articulation design is also used in the Seaon 96CRB. This kind of system was first used in Ocean Bird trimarans designed by John Westell and built by Honnor Marine Ltd of Totnes.
- Telstar trimarans uses a unique horizontal folding design along with a simple mast raising system to facilitate trailer sailing. It can be powered easily with the amas folded in or extended.
DEMOUNTABLES Some trimarans are built demountable to allow them to be trailered to a launch site and then assembled before launching. This takes longer than a folding system but is typically lighter and less costly, and can also be used for craft with too much beam for a folding system. The original Dragonfly Trimarans were once like this and so still is the contemporary W22.
Although it is possible for a trimaran to capsize, this is less frequent than with monohull boats because of the greater resistance to rolling that the amas offer. Most trimaran designs are considered nearly unsinkable because even when filled with water, the flotation of one ama is enough to keep the entire vessel afloat. Because of their stability and safety, special trimarans such as the Challenger, have become popular with sailors who have restricted mobility.
The greater speed compared to monohulls can also become important for safety when weather conditions are bad or threaten to deteriorate because the boat can leave the area of danger faster.
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.
Trimarans capsizes are more likely to be of the pitch-pole type than a roll to one side due to their higher sideways stability and speeds. Capsized trimarans are harder to turn upright after they have turtled than monohull boats. A capsized trimaran should not be righted by sideways rotation as this usually causes heavy damage of the mast and rigging. Harnesses pulling on the stern toward the bow, or from the bow toward the stern of capsized trimarans have been shown to be able to successfully turn them end-over-end. Several design features reduce the chance of pitch-pole capsize. These include having wing nets with an open weave designed to reduce windage and decks and nets that shed water easily. The best way to avoid capsize is to reduce sail in heavy weather.
In their early days, trimarans were rather less robust than monohulls, and ran a greater risk of structural damage in heavy weather. Even today, ocean-going trimaran sailors remain wary of this risk.
Trimarans at anchor or on a mooring tend to follow the wind due to their light weight and shallow draft, whereas monohulls usually follow the tides. This can cause collisions if the trimaran is moored close to a monohull and their swing circles overlap. A correctly rigged bridle to the anchor line should reduce the swing to a minimum.
33rd America's Cup
Competing with a giant trimaran the BMW Oracle Racing team representing the Golden Gate Yacht Club won the 2010 America's Cup on February 14, 2010, off Valencia, Spain, beating the giant catamaran Alinghi 2-0 in the best-of-three series and becoming the first American syndicate to win the cup since 1992. The large rigid wing sail of the USA 17 trimaran provided a decisive advantage and the trimaran won the America's Cup by a considerable margin in each race.
Francis Joyon holds the new world record for solo circumnavigation of the world, set on January 20, 2008. The 51-year-old Frenchman circled the planet alone in 57 days, 13 hours, 34 minutes, 6 seconds in a trimaran. He beat British sailor Ellen MacArthur's record set in February 2005 for which she spent just over 71 days at sea.
French Sailor Loïck Peyron holds the current record for fastest circumnavigation in the trimaran Banque Populaire V. The crewed circumnavigation was completed in 45 days, 13 hours 42 minutes and 53 seconds.
Littoral combat ships built by General Dynamics at Bath Iron Works will be of a trimaran design. USS Independence (LCS-2) is the first of these ships. Littoral combat ships built by Lockheed will be of a monohull design.
First launched in 31 August 2012 at Bali Strait, 63M Carbon Fibre Composite Trimaran Fast Missile Boat (Indonesian: Kapal Cepat Rudal [KCR]) named KRI Klewang (625) - a traditional Indonesian single edge sword, will be the first stealth trimaran of the Indonesian Navy built by North Sea Boats at Banyuwangi, East Java, Indonesia. This ship combines a number of existing advance technologies into a single, unique platform; a wave-piercer trimaran hull from, constructed exclusively of infused vinylester carbon fibre cored sandwich materials for all structural elements, with external "stealth" geometry and features intended to reduce detection. Sadly, the KRI Klewang (625) caught fire because of electrical shortcut in engine room during a maintenance period on September 28, 2012 and was a total loss.
Image gallery sailing trimarans
Image gallery engine driven trimarans
- Collins English Dictionary - 2007 - Harper Collins - ISBN - 978-0-00-780072-8
- Trimaran SeaCart Home Page
- Delivery Benchijigua Express - Austal
- Defence - Littoral Combat Ship (LCS) - Austal
- Defense.gov - Contracts
- DARPA Tactical Technology Office
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- "SwingWing Presentation". Retrieved 2009-05-10.
- David Owen (1970). "Trimariner". Retrieved 2009-05-26.
- "Three Times Three". Retrieved 2009-08-08.
- Earthrace trimaran
- Though it was first announced the ship reached 61 kn: «Pointe de l'Hydroptère à 61 noeuds» (French)
- Les données officielles ont été récupérées, L'Hydroptère, 14 January 2009 (French)
- "Hydroptere: 61 knots and huge crash with 35-38 knots, gusts over 45". Fos-sur-Mer: Catamaran Racing. December 22, 2008. Retrieved November 19, 2013.
- Jim Howard, Charles J. Doane. Handbook of offshore cruising: The Dream and Reality of Modern Ocean Cruising.
- C. A. Marchaj. Aero-Hydrodynamics of Sailing. Tiller Pub. ISBN 1-888671-18-1.