Levathes details the construction of Zhu Di’s ships that came to be known as the “treasure fleet,” built at a pair of shipyards in Nanjing called Longjiang. In early 1403, only a year after he claimed the throne as the Yongle Emperor, Zhu Di ordered a huge project of shipbuilding that would entail the resources of the entire empire. As Levathes writes, “A frenzy of shipbuilding activity followed from 1404 to 1407, with the construction or refitting of over 1,681 ships” (76). Timber was sent from a number of provinces as craftsmen from Fujian moved to Nanjing.

The design of the treasure ships, the largest vessels in the fleet, were a combination of ships called shachuan, from the Yangzi delta region, and fuchuan, from Fujian. The latter were better suited for deep, open-ocean sailing and featured several elements for added stability, such as a keel running the length of the hull. In keeping with the emperor’s idea of grandeur, the ships were enormous, with four decks, nine masts, and 12 sails. Their exact size is unknown because the unit of measure used, the chi, varied from a minimum of nine and a half inches to more than a foot.