Kon-Tiki was the raft used by Norwegian explorer Thor Heyerdahl from Larvik, in his 1947 expedition across the Pacific Ocean from South America to the Polynesian islands. It was named after the Inca sun god, Viracocha, for whom “Kon-Tiki” was said to be an old name. Kon-Tiki is also the name of Heyerdahl´s book; the Academy Award-winning documentary film chronicling his adventures; and the 2012 dramatised feature film nominated for the Academy Award for Best Foreign Language Film.
Heyerdahl believed that people from South America could have settled Polynesia in pre-Columbian times. Although most anthropologists as of 2010 had come to the conclusion they did not, in 2011, new genetic evidence was uncovered by Erik Thorsby that Easter Island inhabitants do have some South American DNA, lending credence to at least some of Heyerdahl´s theses.
His aim in mounting the Kon-Tiki expedition was to show, by using only the materials and technologies available to those people at the time, that there were no technical reasons to prevent them from having done so. Although the expedition carried some modern equipment, such as a radio, watches, charts, sextant, and metal knives, Heyerdahl argued they were incidental to the purpose of proving that the raft itself could make the journey.
The Kon-Tiki expedition was funded by private loans, along with donations of equipment from the United States Army. Heyerdahl and a small team went to Peru, where, with the help of dockyard facilities provided by the Peruvian authorities, they constructed the raft out of balsa logs and other native materials in an indigenous style as recorded in illustrations by Spanish conquistadores.
The trip began on April 28, 1947. Heyerdahl and five companions sailed the raft for 101 days over 6900 km (4,300 miles) across the Pacific Ocean before smashing into a reef at Raroia in the Tuamotu Islands on August 7, 1947. The crew made successful landfall and all returned safely.
The main body of the float was composed of nine balsa tree trunks up to 45 ft long, 2 ft in diameter, lashed together with 1¼ inch hemp ropes. Cross-pieces of balsa logs 18 ft long and 1 ft in diameter were lashed across the logs at 3 ft intervals to give lateral support. Pine splashboards clad the bow, and lengths of pine 1 inch thick and 2 ft wide were wedged between the balsa logs and used as centreboards.
The main mast was made of lengths of mangrove wood lashed together to form an A-frame 29 ft high. Behind the main-mast was a cabin of plaited bamboo 14 ft long and 8 ft wide was built about 4–5 ft high, and roofed with banana leaf thatch. At the stern was a 19 ft long steering oar of mangrove wood, with a blade of fir. The main sail was 15 by 18 ft on a yard of bamboo stems lashed together. Photographs also show a top-sail above the main sail, and also a mizzen-sail, mounted at the stern.
The raft was partially decked in split bamboo. The main spars were a laminate of wood and reeds and Heyerdahl tested more than twenty different composites before settling on one that proved an effective compromise between bulk and torsional rigidity. No metal was used in the construction.
The original Kon-Tiki raft is now on display in the Kon-Tiki Museum in Bygdøy.