Native Balsa Raft Sketch by F.E. Paris (1841) showing construction of a native balsa raft from the north-west coast of South America. The maximum length of raft is 80-90 feet, maximum width of a raft is 25-30 feet with a freight capacity of 20-25 tons.
Searoutes to Polynesia:
http://www.bradshawfoundation.com/thor/
Stone technology on Easter Island:
http://www.mysteriousplaces.com/Easter_Island/html/tour3.html