either of two papyrus boats with which the Norwegian scientist-explorer Thor Heyerdahl (Heyerdahl, Thor) crossed the Atlantic in 1969–70 to demonstrate the possibility of cultural contact between early peoples of Africa and Central and South America. The first was built in Egypt by boatbuilders Heyerdahl hired from Lake Chad, where reed boats are commonplace. Manned by seven men chosen from seven nations, “Ra” sailed from Safi, Mor., May 25, 1969, but defects in design and cargo loading, the result of inexperience, caused it slowly to founder in July after sailing 3,000 miles. With nearly the same crew, but with a boat (“Ra II”) built by Aymaro Indians of Lake Titicaca, Heyerdahl repeated his adventure in 1970, completing the crossing of the Atlantic from Safi to Barbados, West Indies, in 57 days (May 17 to July 12).