A question from Yahoo! Answers:
Why did china lose its edge in shipbuilding technology?
Because this edge did not serve any commercial interests. It rested on two pillars, admiral Zheng He and financial support given to him by the emperors of Ming dynasty.
Zheng’s missions resulted mostly in establishing diplomatic relations with faraway countries and exchange of royal gifts (such as zebras and giraffes for the imperial gardens) and were unbelievably costly (his fleet at its height included 300 ships and 20,000 men).
Zheng died during his last expedition, so there was no one else to lobby for maintenance and expansion of the fleet (partly because Zheng, being a Muslim, was always somewhat of an outsider in court). Moreover, many courtiers thought that private long-distance sea travel should be discouraged (just as any other private contact with foreign lands), and by 1500, no ship with two or more masts could leave a Chinese port without government permission; sailing a large ship without a permit became a capital offense…