A catamaran (From Tamil 'kattumaram')[1] is a type of multihulled boat or ship consisting of two hulls, or vakas, joined by some structure, the most basic being a frame, formed of akas. Catamarans can be sail- or engine-powered. The catamaran was first discovered being used by the paravas, a fishing community in the southern coast of Tamil Nadu, India. Catamarans were used by the ancient Tamil Chola dynasty as early as the 5th century AD for moving their fleets to invade such Southeast Asian regions as Burma, Indonesia and Malaysia.
Catamarans are a relatively recent introduction to the design of boats for both leisure and sport sailing, although they have been used for millennia in Oceania, where Polynesian catamarans and outrigger canoes allowed seafaring Polynesians to settle the world's most far-flung islands.
In recreational sailing, catamarans, and multihulls in general, have been met by a degree of skepticism from Western sailors accustomed to more "traditional" monohull designs[2], mainly because multihulls were based on, to them, completely alien and strange concepts, with balance based on geometry rather than weight distribution. However, the catamaran has arguably become the best hullform for fast ferries, because their powering characteristics and spacious arrangements are valuable.
History
While the English adventurer and buccaneer William Dampier was traveling around the world in the 1690s in search of business opportunities, he found himself on the southeastern coast of India, in Tamil Nadu on the Bay of Bengal. He was the first to write in English about a kind of vessel he observed there. It was little more than a raft made of logs.
On the coast of Coromandel," he wrote in 1697, "they call them Catamarans. These are but one Log, or two, sometimes of a sort of light Wood ... so small, that they carry but one Man, whose legs and breech are always in the Water.
Although the name came from Tamil, the modern catamaran came from the South Pacific. English visitors applied the Tamil name catamaran to the swift, stable sail and paddle boats made out of two widely separated logs and used by Polynesian natives to get from one island to another.
The design remained relatively unknown in the West for almost another 200 years, until an American, Nathanael Herreshoff, began to build catamaran boats of his own design in 1877 (US Pat. No. 189,459), namely 'Amaryllis', which immediately showed her superior performance capabilities, at her maiden regatta (The Centennial Regatta held on June 22, 1876, off the New York Yacht Club's Staten Island station[2]). It was this same event, after being protested by the losers, where Catamarans, as a design, were barred from all the regular classes[2] and they remained barred until the 1970s.
This ban relegated the catamaran to being a mere novelty boat design until 1947[5]. In 1947, surfing legend, Woodbridge "Woody" Brown and Alfred Kumalae designed and built the first modern ocean-going catamaran, Manu Kai, in Hawaii. Their young assistant was Rudy Choy, who later founded the design firm Choy/Seaman/Kumalae (C/S/K, 1957) and became a fountainhead for the catamaran movement. The Prout Brothers, Roland and Francis, experimented with catamarans in 1949 and converted their 1935 boat factory in Canvey Island, Essex (England), to catamaran production in 1954. Their Shearwater catamarans won races easily against the single hulled yachts.
The speed and stability of these catamarans soon made them a popular pleasure craft, with their popularity really taking off in Europe, and was followed soon thereafter in America. Currently, most individually owned catamarans are built in France, South Africa, and Australia.
In the mid-twentieth century, the catamaran inspired an even more popular sailboat, the Beach Cat. In California, a maker of surfboards, Hobie Alter produced the 250-pound Hobie Cat 14 in 1967, and two years later the larger and even more successful Hobie 16. That boat remains in production, with more than 100,000 made in the past three decades.
The Tornado catamaran is an Olympic class sailing catamaran, with a crew of two. It has been in the Olympic Games since 1976. It was designed in 1967 by Rodney March of Brightlingsea, England, with help from Terry Pierce, and Reg White, specifically for the purpose of becoming the Olympic catamaran. At the IYRU Olympic Catamaran Trials, it easily defeated the other challengers.
Other important builders of catamarans are Austal and Incat, both of Australia and best known for building large catamarans both as civilian ferries and as naval vessels.
Usage and Application
Sailing Beach Catamarans
Although the principles of sailing are the same for both catamarans and monohulls, there are some "peculiarities" to sailing catamarans. For example:
- Catamarans can be harder to tack if they don't have dagger boards or centre boards. All sailboats must resist lateral movement in order to sail in directions other than downwind and they do this by either the hull itself or else dagger boards or centre boards. Also, because catamarans are lighter in proportion to their sail size, they have less momentum to carry them through the turn when they are head to wind. Correct use of the jib sail (back-filling the jib to pull the bow around) is often essential in successfully completing a tack without ending up stuck in irons (pointing dead into the wind and sailing backwards, see: No-Go Zone).
- They have a higher speed than other sailboats of the same size. This is because they can have a much larger sail area due to the larger righting moment. They can reach over 1.5 times the speed of the wind.
- Catamarans are less likely to capsize in the classic 'beam-wise' manner but often have a tendency to pitchpole instead - where the leeward (downwind) bow sinks into the water and the boat 'trips' over forward, leading to a capsize.[citation needed]
Teaching for new sailors is usually carried out in monohulls as they are thought easier to learn to sail, a mixture of all the differences mentioned probably contributes to this.
Catamarans, and multihulls in general, are normally faster than single-hull boats for three reasons:
- catamarans are lighter due to the fact there is no keel counterweight;
- catamarans have a wider beam (the distance from one side of the boat to the other), which makes them more stable and therefore able to carry more sail area per unit of length than an equivalent monohull; and
- the greater stability means that the sail is more likely to stay upright in a gust, drawing more power than a monohull's sail which is more likely to heel (lean) over.
A catamaran is most likely to achieve its maximum speed when its forward motion is not unduly disturbed by wave action. This is achieved in waters where the wavelength of the waves is somewhat greater than the waterline length of the hulls, or it is achieved by the design piercing the waves. In either case pitching (rocking horse-like motion) is reduced. This has led to it being said that catamarans are especially favourable in coastal waters, where the often sheltered waters permit the boat to reach and maintain its maximum speed.
Catamarans make good cruising and long distance boats: The Race (around the world, in 2001) was won by the giant catamaran Club Med skippered by Grant Dalton. It went round the earth in 62 days at an average speed of eighteen knots.
Nema komentara:
Objavi komentar