Tropical Monsoon and Chang Ho's Voyages to the West of Indian Ocean

Chang Ho's voyages to the west of India Ocean had close relationship with Asian tropical and subtropical monsoon. The seventh voyage of Chang Ho's fleet, started in 1432 and ended in 1433, was recorded in Qian Wen Ji, the book compiled by Yuan-yi Mao in the Ming Dynasty. Based on this record, Chang Ho's voyage was reconstructed and analyzed. The research shows that the real starting point of Chang Ho's voyages was Chang Le port in Fu-kien province. In this area, steady subtropical northeast monsoon was prevailing in winter and early spring, the fleet could fully take advantage of it for its marine mission. Whether Chang Ho's voyages went to Calicut or Ormuz, it would take one and half year to complete the journey. This travel schedule was mainly determined by Asian monsoon. Because the limitation of monsoon, the fleet had to stayed at several special places for a quite long time to wait for wind changes. For the same reason, the fleet had to send branches at several points for sailing to countries in different direction.Surabaya was the first wind waiting spot, where the fleet stayed waiting for tropical southeast monsoon. Atcheh was the second wind waiting spot, where the fleet waited for northeast monsoon coming again. Atcheh was also the first divergent spot, at this place the branch fleet were sent to Bengle in the north. Calicut was the second divergent spot, from there the branches were sent to Aden, Djofar in Arabian Peninsula and Mogedoxu , Malinde in East Africa, were the places where the main fleet kept sailing for Ormuz in the northwest meanwhile.The convergent place was considerably set up at Malacca, where the main fleet and the branches met again and sailed back China with the southwest monsoon.