Raft

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Traditional raft, from the 1884 edition of Adventures of Huckleberry Finn Huck-and-jim-on-raft.jpg
Traditional raft, from the 1884 edition of Adventures of Huckleberry Finn

A raft is any flat structure for support or transportation over water. [1] It is usually of basic design, characterized by the absence of a hull. Rafts are usually kept afloat by using any combination of buoyant materials such as wood, sealed barrels, or inflated air chambers (such as pontoons), and are typically not propelled by an engine.

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Human-made rafts

Sketch by F.E. Paris (1841) showing construction of a native Peruvian balsa raft Raft guara.jpg
Sketch by F.E. Paris (1841) showing construction of a native Peruvian balsa raft

Traditional or primitive rafts were constructed of wood or reeds. Modern rafts may also use pontoons, drums, or extruded polystyrene blocks.[ citation needed ] Inflatable rafts up to the 20th century used flotation chambers made of goat- or buffalo-skins, but most now[ when? ] use durable, multi-layered rubberized fabrics. Depending on its use and size, it may have a superstructure, masts, or rudders.

Timber rafting is used by the logging industry for the transportation of logs, by tying them together into rafts and drifting or pulling them down a river.[ citation needed ] This method was very common up until the middle of the 20th century but is now[ when? ] used only rarely.

Lumber rafts on the Peter I Canal. Early 20th-century picture by S. Prokudin-Gorsky. Gorskii 04417u.jpg
Lumber rafts on the Peter I Canal. Early 20th-century picture by S. Prokudin-Gorsky.

Large rafts made of balsa logs and using sails for navigation were important in maritime trade on the Pacific Ocean coast of South America from pre-Columbian times until the 19th century. Voyages were made to locations as far away as Mexico, and many trans-Pacific voyages using replicas of ancient rafts have been undertaken to demonstrate possible contacts between South America and Polynesia. [2]

The type of raft used for recreational rafting is almost exclusively an inflatable raft, manufactured of flexible materials for use on whitewater.

Natural rafts

In biology, particularly in island biogeography, non-manmade rafts are an important concept. Such rafts consist of matted clumps of vegetation that has been swept off the dry land by a storm, tsunami, tide, earthquake or similar event; in modern times[ when? ] they sometimes also incorporate other kind of flotsam and jetsam, e.g. plastic containers. They stay afloat by its natural buoyancy and can travel for hundreds, even thousands of miles and are ultimately destroyed by wave action and decomposition, or make landfall.[ citation needed ]

Rafting events are important means of oceanic dispersal for non-flying animals. For small mammals, amphibians and reptiles in particular, but for many invertebrates as well, such rafts of vegetation are often the only means by which they could reach and if they are lucky colonize oceanic islands before human-built vehicles provided another mode of transport.[ citation needed ]

See also

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Vital Alsar Pacific raft expeditions

Between 1966 and 1973, Spanish explorer Vital Alsar led three expeditions to cross the Pacific Ocean by raft - La Pacífica in 1966, La Balsa in 1970 and Las Balsas in 1973. Travelling from Ecuador, South America, to Australia, the first expedition failed, but the second and third succeeded, both setting the record for the longest known raft voyages in history - 8,600 miles (13,800 km) and 9,000 miles (14,000 km) respectively.

Pre-Columbian rafts plied the Pacific Coast of South America for trade from about 100 BCE, and possibly much earlier. The 16th century descriptions by the Spanish of the rafts used by Native Americans along the seacoasts of Peru and Ecuador has incited speculation about the seamanship of the Indians, the seaworthiness of their rafts, and the possibility that they undertook long ocean-going voyages. None of the prehistoric rafts have survived and the exact characteristics of their construction and the geographical extent of their voyages are uncertain.

References

  1. G. & C. Merriam Co., Websters New Collegiate Dictionary, 1976, ISBN   0-87779-339-5
  2. Smith, Cameron M. and Haslett, John F. (1999), "Construction and Sailing Characteristics of a Pre-Columbian Raft Replica", Bulletin of Primitive Technology, pp. 13–18
  3. Thomas T. Taber, III "Williamsport Lumber Capital", 1995, page 13