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. [1]
Counter-intuitively, it is unhelpful to think of the design progression to be "1-2-3", namely monohull - catamaran - trimaran; rather, it is "1-3-2". A sailing trimaran is, in effect, a modified monohull with lightweight outrigger hulls (or "amas") for stability instead of a heavy deep keel; so it follows that a sailing trimaran will be lighter and faster than a sailing monohull. [2] A sailing trimaran will have a centre hull that may comprise up to 90% of total hull volume, and 95% of total deadweight.
A sailing trimaran at rest will have both amas out of the water and, when heeled, will only ever have one of the amas immersed. As a trimaran heels further, that leeward ama will submerge even more deeply, providing increased stability and buoyancy. A monohull will heel much more than a trimaran, which will in turn heel a little more than a catamaran which typically heels up to 5° or 10°. For leisure cruising, a catamaran is more spacious than an equivalent monohull or a trimaran, but a cruising trimaran can have a greater load-carrying ability than a catamaran, due to its monohull-like centre hull. [3]
Single-outrigger boats, double-canoes (catamarans), and double-outrigger boats (trimarans) of the Austronesian peoples are the direct antecedents of modern multihull vessels. They were developed during the Austronesian Expansion (c. 3000 to 1500 BC) which allowed Austronesians to colonize maritime Southeast Asia, Micronesia, Island Melanesia, Madagascar, and Polynesia. These Austronesian vessels are still widely used today by traditional fishermen in Austronesian regions in maritime Southeast Asia, Oceania and Madagascar; as well as areas they were introduced to by Austronesians in ancient times like in the East African coast and in South Asia. [4] [5] [6] [7] [8]
Greek sources also describe large third-century BC catamarans, one built under the supervision of Archimedes, the Syracusia , [9] and another reportedly built by Ptolemy IV Philopator of Egypt, the Tessarakonteres . [10] [11]
Modern pioneers of multihull design include James Wharram (UK), Derek Kelsall (UK), Tom Lack (UK), Lock Crowther (Aust), Hedly Nicol (Aust), Malcolm Tennant (NZ), Jim Brown (USA), Arthur Piver (USA), Chris White (US), Ian Farrier (NZ), LOMOcean (NZ), Darren Newton (UK), Jens Quorning (DK) and Dick Newick (USA).
A single-outrigger canoe is a canoe with a slender outrigger ("ama") attached by two or more struts ("akas"). This craft will normally be propelled by paddles. Single-outrigger canoes that use sails are usually inaccurately referred to by the name "proa". While single-outrigger canoes and proas both derive stability from the outrigger, the proa has the greater need of the outrigger to counter the heeling effect of the sail. The outrigger on a proa can either be on the lee or windward side, or in a tacking proa, interchangeable. However, more recently, proas tend to keep the outrigger either to leeward or to wind which means that instead of tacking, a "shunt" is required, whereby the bow becomes the stern, and the stern becomes the bow.
A catamaran is a vessel with twin hulls. Commercial catamarans began in 17th century England. Separate attempts at steam-powered catamarans were carried out by the middle of the 20th century. However, success required better materials and more developed hydrodynamic technologies. During the second half of the 20th century catamaran designs flourished. Catamaran configurations are used for racing, sailing, tourist and fishing boats.
The hulls of a catamaran are typically connected by a bridgedeck, although some simpler cruising catamarans [12] simply have a trampoline stretched between the crossbeams (or "akas"). [13] Small beachable catamarans, such as the Hobie Cat, also have only a trampoline between the hulls.
Catamarans derive stability from the distance between the hulls—transverse clearance—the greater this distance, the greater the stability. [14] Typically, catamaran hulls are slim, although they may flare above the waterline to give reserve buoyancy. [15] The vertical clearance between the design waterplane and the bottom of the bridge deck determines the likelihood of contact with waves. Increased vertical clearance diminishes such contact and increases seaworthiness, within limits. [16]
A trimaran (or double-outrigger) is a vessel with two outrigger floats attached on either side of a main hull by a crossbeam, wing, or other form of superstructure. They are derived from traditional double-outrigger vessels of maritime Southeast Asia. [4] [5] [6] Despite not being traditionally Polynesian, [7] [8] western trimarans use traditional Polynesian terms for the hull (vaka), the floats (ama), and connectors (aka). [17] The word trimaran is a portmanteau of tri and (cata)maran, [18] a term that is thought to have been coined by Victor Tchetchet, a pioneering modern multihull designer, born in Ukraine (at that time part of the Russian Empire). [19]
Some trimaran configurations use the outlying hulls to enhance stability and allow for shallow draft, examples include the experimental ship RV Triton [20] and the Independence class of littoral combat ships (US). [21]
Some multihulls with four (quadrimaran) or five (pentamaran) hulls have been proposed; few have been built. [22] A Swiss entrepreneur is attempting to raise €25 million [23] to build a sail-driven quadrimaran that would use solar power to scoop plastic from the ocean; the project is scheduled for launch in 2020. [24] A French manufacturer, Tera-4, produces motor quadrimarans which use aerodynamic lift between the four hulls to promote planing and reduce power consumption. [25]
Design concepts for vessels with two pair of outriggers have been referred to as pentamarans. The design concept comprises a narrow, long hull that cuts through waves. The outriggers then provide the stability that such a narrow hull needs. While the aft sponsons act as trimaran sponsons do, the front sponsons do not touch the water normally; only if the ship rolls to one side do they provide added buoyancy to correct the roll. [26] [27] BMT Group, a shipbuilding and engineering company in the UK, has proposed a fast cargo ship and a yacht using this kind of hull. [28] [29]
Multihull designs may have hull beams that are slimmer at the water surface ("waterplane") than underwater. This arrangement allows good wave-piercing, while keeping a buoyant hydrodynamic hull beneath the waterplane. In a catamaran configuration this is called a small waterplane area twin hull, or SWATH. [30] While SWATHs are stable in rough seas, they have the drawbacks, compared with other catamarans, of having a deeper draft, being more sensitive to loading, and requiring more power because of their higher underwater surface areas. [31] Triple-hull configurations of small waterplane area craft had been studied, but not built, as of 2008. [32]
Each hull of a multihull vessel can be narrower than that of a monohull with the same displacement [33] and long, narrow hulls, a multihull typically produces very small bow waves and wakes, a consequence of a favorable Froude number. [34] [35] [36] Vessels with beamy hulls (typically monohulls) normally create a large bow wave and wake. Such a vessel is limited by its "hull speed", being unable to "climb over" its bow wave unless it changes from displacement mode to planing mode. Vessels with slim hulls (typically multihulls) will normally create no appreciable bow wave to limit their progress.
In 1978, 101 years after catamarans like Amaryllis were banned from yacht racing [37] they returned to the sport. This started with the victory of the trimaran Olympus Photo , skippered by Mike Birch in the first Route du Rhum. Thereafter, no open ocean race was won by a monohull. Winning times dropped by 70%, since 1978. Olympus Photo's 23-day 6 hr 58' 35" success dropped to Gitana 11's 7d 17h 19'6", in 2006. Around 2016 the first large wind driven foil-borne racing catamarans were built. These cats rise onto foils and T-foiled rudders only at higher speeds.[ citation needed ]
The increasing popularity of catamaran since the 1960s is down to the added space, speed, shallow draft, and lack of heeling underway. The stability of a multihull makes sailing much less tiring for the crew, and is particularly suitable for families. Having no need for ballast for stability, multihulls are much lighter than monohull sailboats; but a multihull's fine hull sections mean that one must take care not to overload the vessel. Powerboats catamarans are increasingly used for racing, cruising and as workboats and fishing boats. Speed, the stable working platform, safety, and added space are the prime advantages for power cats.
"The weight of a multihull, of this length, is probably not much more than half the weight of a monohull of the same length and it can be sailed with less crew effort." [38]
Racing catamarans and trimarans are popular in France, New Zealand and Australia. Cruising cats are commonest in the Caribbean and Mediterranean (where they form the bulk of the charter business) and Australia. Multihulls are less common in the US, perhaps because their increased beam require wider dock/slips. Smaller multihulls may be collapsible and trailerable, and thus suitable for daybooks and racers. Until the 1960s most multihull sailboats (except for beach cats) were built either by their owners or by boat builders; since then companies have been selling mass-produced boats, of which there are more than 150 models. [39]
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A sailboat or sailing boat is a boat propelled partly or entirely by sails and is smaller than a sailing ship. Distinctions in what constitutes a sailing boat and ship vary by region and maritime culture.
A catamaran is a multi-hulled watercraft featuring two parallel hulls of equal size. It is a geometry-stabilized craft, deriving its stability from its wide beam, rather than from a ballasted keel as with a monohull boat. Catamarans typically have less hull volume, smaller displacement, and shallower draft (draught) than monohulls of comparable length. The two hulls combined also often have a smaller hydrodynamic resistance than comparable monohulls, requiring less propulsive power from either sails or motors. The catamaran's wider stance on the water can reduce both heeling and wave-induced motion, as compared with a monohull, and can give reduced wakes.
A trimaran is a multihull boat that comprises a main hull and two smaller outrigger hulls which are attached to the main hull with lateral beams. Most modern trimarans are sailing yachts designed for recreation or racing; others are ferries or warships. They originated from the traditional double-outrigger hulls of the Austronesian cultures of Maritime Southeast Asia; particularly in the Philippines and Eastern Indonesia, where it remains the dominant hull design of traditional fishing boats. Double-outriggers are derived from the older catamaran and single-outrigger boat designs.
An outrigger is a projecting structure on a boat, with specific meaning depending on types of vessel. Outriggers may also refer to legs on a wheeled vehicle that are folded out when it needs stabilization, for example on a crane that lifts heavy loads.
A monohull is a type of boat having only one hull, unlike multihulled boats which can have two or more individual hulls connected to one another.
Outrigger boats are various watercraft featuring one or more lateral support floats known as outriggers, which are fastened to one or both sides of the main hull. They can range from small dugout canoes to large plank-built vessels. Outrigger boats can also vary in their configuration, from the ancestral double-hull configuration (catamarans), to single-outrigger vessels prevalent in the Pacific Islands and Madagascar, to the double-outrigger vessels (trimarans) prevalent in Island Southeast Asia. They are traditionally fitted with Austronesian sails, like the crab claw sails and tanja sails, but in modern times are often fitted with petrol engines.
Proas are various types of multi-hull outrigger sailboats of the Austronesian peoples. The terms were used for native Austronesian ships in European records during the Colonial era indiscriminately, and thus can confusingly refer to the double-ended single-outrigger boats of Oceania, the double-outrigger boats of Island Southeast Asia, and sometimes ships with no outriggers or sails at all.
Hobie Cat is a company that manufactures sailing catamarans, surfboards, sailboats, kayaks, stand-up paddle boards, and pedalboards as the Hobie Cat Company. It was founded in 1961 by Hobart Alter, who originally manufactured surfboards. Its line of products has included more than twenty sailing craft, plus a variety of other watercraft.
Canoe sailing refers to the practice of fitting an Austronesian outrigger or Western canoe with sails.
The beam of a ship is its width at its widest point. The maximum beam (BMAX) is the distance between planes passing through the outer extremities of the ship, beam of the hull (BH) only includes permanently fixed parts of the hull, and beam at waterline (BWL) is the maximum width where the hull intersects the surface of the water.
In dinghy sailing, a boat is said to be turtling or to turn turtle when the boat is fully inverted with the mast pointing down to the lake bottom, riverbed, or seabed. The name stems from the appearance of the upside-down boat, similar to the carapace of a sea turtle. The term can be applied to any vessel; turning turtle is less frequent but more dangerous on ships than on smaller boats. It is rarer but more hazardous for multihulls than for monohulls, because of multihulls are harder to flip in both directions. Measures can be taken to prevent a capsize from becoming a turtle.
The crab claw sail is a fore-and-aft triangular sail with spars along upper and lower edges. The crab claw sail was first developed by the Austronesian peoples by at least 2000 BCE. It is used in many traditional Austronesian cultures in Island Southeast Asia, Micronesia, Island Melanesia, Polynesia, and Madagascar. Due to its extraordinary performance and ease of operation, it has also become very popular in modern sport sailing. It is sometimes known as the Oceanic lateen or the Oceanic sprit, even though it is not restricted to Oceania, is neither a lateen sail nor a spritsail, and has an independent older origin.
A wave-piercing boat hull has a very fine bow, with reduced buoyancy in the forward portions. When a wave is encountered, the lack of buoyancy means the hull pierces through the water rather than riding over the top, resulting in a smoother ride than traditional designs, and in diminished mechanical stress on the vessel. It also reduces a boat's wave-making resistance.
A sailing yacht, is a leisure craft that uses sails as its primary means of propulsion. A yacht may be a sail or power vessel used for pleasure, cruising, or racing. There is no standard definition, so the term applies here to sailing vessels that have a cabin with amenities that accommodate overnight use. To be termed a "yacht", as opposed to a "boat", such a vessel is likely to be at least 33 feet (10 m) in length and have been judged to have good aesthetic qualities. Sailboats that do not accommodate overnight use or are smaller than 30 feet (9.1 m) are not universally called yachts. Sailing yachts in excess of 130 feet (40 m) are generally considered to be superyachts.
Telstar trimarans is a line of trimarans most recently built by the Performance Cruising Inc shipyard in Annapolis, Maryland.
VPLP design is a French-based naval architectural firm founded by Marc Van Peteghem and Vincent Lauriot-Prévost, responsible for designing some of the world's most innovative racing boats. Their designs presently hold many of the World Speed Sailing records.
The Ocean Bird is a class of trimaran sailboat designed by John Westell and produced by Honnor Marine Ltd. at Totnes, Teignmouth in the 1970s, featuring fold-in lateral floats on a webless steel-beam frame chosen to provide stability against heeling, yet allow a compact footprint in harbour.
Kaep is a traditional type of double-ended Proa sailboat native to Palau. Some of the essential design elements have also been adopted as a modern smaller multihull prototype variant.
Polynesian multihull terminology, such as "ama", "aka" and "vaka" are multihull terms that have been widely adopted beyond the South Pacific where these terms originated. This Polynesian terminology is in common use in the Americas and the Pacific but is almost unknown in Europe, where the Anglo-Saxon terms "hull" and "outrigger" form normal parlance. Outriggers, catamarans, and outrigger boats are a common heritage of all Austronesian peoples and predate the Micronesian and Polynesian expansion into the Pacific. They are also the dominant forms of traditional ships in Island Southeast Asian and Malagasy Austronesian cultures, where local terms are used.
The Austronesian vessels, are those devised by the Austronesian peoples of Taiwan, Maritime Southeast Asia, Micronesia, coastal New Guinea, Island Melanesia, Polynesia, and Madagascar that speak Austronesian languages. They also include indigenous ethnic minorities in Vietnam, Cambodia, Myanmar, Thailand, Hainan, the Comoros, and the Torres Strait Islands. The vessels have carried trade and migration across long distances in the region. They include monohulls, catamarans, outriggers, and proas. Sail types include a variety of crab-claw and tanja configurations.
