The largest ships of the Ming fleet dwarfed Columbus' flagship the Santa Maria. In fact the Chinese ships were the largest wooded sailing vessels ever built. Their water tight compartment structure was more than four centuries ahead in design to that of the European ships of the time.
For reasons still unclear, the Ming Dynasty not only suddenly stopped the expeditions, they actually destroyed all craft capable of ocean travel in the Empire, burned most of the records of the voyages and forbid Chinese from any future trade, exploration or colonization outside the current boundaries of the Ming lands. A major turning point in Chinese and World history had been reached; the greatest most advanced naval power of the age turned its back on the World and destroyed its superiority, choosing self imposed exile from the World stage. China would become an isolationist nation locked in the 15th Century for the next four centuries, all the while the rest of the World would continue to advance in technology and knowledge. The long age of Chinese technological superiority had ended