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A Jangada is a traditional fishing boat made of wood used in the northern region of Brazil. Some claim the historical legacy of the jangada dates back to the ancient Greeks and that it was Ulysses' vessel in The Odyssey.〔Lima, Paul (The raft men of Brazil ) Retrieved 25 April 2008〕 The construction of the jangada incorporates some improvements in neolithic handcraft - better materials were found and the physics of sailing was better observed through experimentation. The details are closely guarded by artisans. Its triangular sail makes use of some effects of fluid dynamics. Also known as a "latin" (lateen) sail, it allows one to sail against the wind, taking advantage of the pressure difference on the air that rises on its external face (the one that becomes convex for the internal wind pressure) and its internal face (the one that becomes concave, the side where the sailor goes). Some big watercraft also used the Latin sail, but in a limited manner, because its successful use was crucially dependent on the presence of the sailor, who must be aware of the wind movements: the pressure difference is manipulated constantly whilst sailing against the wind. The same principles are used to keep a plane in the air, thanks to its wing geometry. In the jangada, there is a gracious curve almost parabolic on the upper part of the triangle, and another one more extended and short, below. This asymmetry is due to the manipulation high of the mast, that turns gently - this time using the lever mechanic principle - around its axis. ==Construction== Its construction depends on the correct use of materials such as fluctuation woods (like the Brazilian balsa, and other rare species), artisan tissues and ropes. The traditional Jangada doesn't have any metallic elements like nails; its structure is completely put together with joints and lashings using ropes made of hand-woven fibers. The jangada is typically made using 6 wooden logs rafted together in parallel: two in the center (called "meios", or central ones), 2 more on either side of those (called "mimburas", a Tupi word), and 2 on the outside, called "bordos". The 4 most central logs ("meios" and "mimburas") are united using hard wooden pegs, made of stronger wood than the logs. The "bordos" are then bound to the "mimburas" using more wooden pegs, so they can be more elevated. On this basic platform, two wooden seats are installed, each one supported by 4 elegant wooden rods, locked on the "mimburas". On these rods, a piece of wood is fixed to make the seat. The most central seat supports the jangada's mast. The other seat, also called the "master seat", because the man who sits on it sails and steers the jangada with an oar. The master's oar is fixed between one of the "mimburas" and one of the "meios". There is another opening between the two meios, to allow for the "bolina" board (from the English "bowline"). This board acts as a centerboard, and can be adjusted in height and angle (in a more limited way, on the medial plan of the watercraft). The "bolina" board reduces the sideways motion of the jangada when it is sailed close-hauled. All of the traditional jangada's components are handmade, from the mast to the sail, the ropes to the sailing seat, fishing nets, fishing hooks, anchors, and the boxes used to keep fish and belongings. Its crew, on the traditional versions of the jangada, ranges from 3 to 5 people. This group works on a space of approximately 5 to 7 meters, on average (although there are jangadas larger than 8 meters), and a space of 1.4 to 1.7 meters on its smaller extension. Its dimensions are the results of a series of nautical limitations, including: the size of the available wood, the resistance of the joints and lashings, the necessary strength to move it over the waves, the size of the sail and the work the wind makes over them, the human force needed, so that just one man (once a time, taking turns) can operate it. It is ergonomically designed and administrated, when this artisan watercraft is examined through the eyes of modern designers. The traditional fisherman always obeyed the known rules of the use of the tides, the wind rules, the currents and the seasonal effects on fishing. Due to these factors the incursions on the sea vary much in relation to the duration of the voyage, the course followed and the type of fish netted. A common voyage used to last three days to a week (sometimes more, according to old fishermen) on the high seas, up to 120 km from the coast. This type of voyage is getting rarer as the jangada sailer now rarely sails for more than three days and will sail no farther than 50 km out from the coast. At the same time groups of jangadas voyaging together are getting rarer; the most common voyage now is a single fishing crew on a single jangada. However, in many points along the coast especially Ceará, there are jangada races, being very famous the one that occurs on the Mucuripe port, Fortaleza. Dozens of jangadas take part on popular competitions, in a single spectacle on the broad Brazilian coast. 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「Jangada」の詳細全文を読む スポンサード リンク
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