Araft is any flat structure for support or transportation over water.[1] It is usually of basic design, characterized by the absence of ahull. Rafts are usually kept afloat by using any combination of buoyant materials such aswood, sealedbarrels, or inflated air chambers (such aspontoons), and are typically not propelled by an engine. Rafts are an ancient mode of transport; naturally-occurring rafts such as entwined vegetation and pieces of wood have been used to traverse water since the dawn of humanity.
Sketch by F.E. Paris (1841) showing construction of a native Peruvian balsa raft
Traditional or primitive rafts were constructed of wood, bamboo orreeds; early buoyed or float rafts use inflated animal skins or sealed clay pots which are lashed together.[2]: 15, 17, 43 Modern float rafts may also usepontoons,drums, orextruded polystyrene blocks. Depending on its use and size, it may have asuperstructure, masts, or rudders.
Timber rafting is used by thelogging 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.
Large rafts made ofbalsa 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 andPolynesia.[3]
Rafts used for recreationalrafting are almost exclusively inflatable rafts, manufactured of flexible materials such as PVC, hypalon, polyurethane, and nylon.[4] These materials are resistant to the collisions and heavy wear the boats experience when traveling throughwhitewater.[4] Whitewater rafts are also designed with high rocker, a raised bow and stern which allows them to pass over waves and obstacles more easily.[5] Most have drain holes in the floor to prevent the boat from becoming swamped with water.
Inbiology, particularly inisland biogeography, non-manmade rafts are an important concept. Such rafts consist of matted clumps ofvegetation that has been swept off the dry land by astorm,tsunami,tide,earthquake or similar event; in modern times[when?] they sometimes also incorporate other kind offlotsam and jetsam, e.g. plastic containers. They stay afloat by its naturalbuoyancy and can travel for hundreds, even thousands of miles and are ultimately destroyed bywave action anddecomposition, or make landfall.[citation needed]
Three Arks for a log drive onPine Creek, in Lycoming or Tioga County, Pennsylvania. The left ark was for cooking and dining, the middle ark was the sleeping quarters and the right ark was for the horses. The arks were built for just one log drive and then sold for their lumber. The line of the Jersey Shore, Pine Creek and Buffalo Railway can be seen on the eastern shore: the mountainside behind it is nearly bare of trees from clearcutting.[6]
^G. & C. Merriam Co.,Websters New Collegiate Dictionary, 1976,ISBN0-87779-339-5
^McGrail, Sean (2014).Early ships and seafaring : water transport beyond Europe. Barnsley: Pen and Sword Books Limited.ISBN9781473825598.
^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
