1418 Admiral Zheng discovered America?

My opinion is Admiral Zheng did visit America, unfortunately due to internal politics China stopped visiting the outside world. It's amazing the difference in size between Admiral Zheng's ships, and the ones in Columbus's fleet.

Zheng's Fleet Vs. Columbus:
Zheng's ship was 400 ft. long vs.  Columbus's largest ship was only 85 feet long
300 ships, vs. 3 ships
28,000 men vs. 90

Does this map from 1418 prove historian's controversial claim that the New World was discovered by the CHINESE 70 years before Columbus? - Daily News