What was the key to the success of Columbus?

I would say that there were two, which one is more important is a matter of opinion. One was the trade winds. Columbus had figured out that there were strong, steady winds blowing east to west and then west to east according to the season, that would take ships all the way across the Atlantic Ocean. Without those nearly continuous winds the ships of the day could not have made the voyage. The other one was the existence of the Americas. Columbus wasn't trying to discover America, he was trying to sail to Asia. He had greviously understimated the size of the globe. That was the real reason that there was so much opposition to his voyage, not because scholars thought the Earth was flat, but because they knew that it was about 12,000 miles from Europe to Asia while Columbus was claiming it was only about 3,000 miles. Caravelles could never have sailed all the way to Asia. Even if they could have withstood the journey physically (doubtful) they could not carry enough food and water for a voyage that long. Had the American continents not been where they were, Columbus's crews would have died of thirst in the middle of the vast ocean. Also may I add that none of the portrits that we see today of him are all fake he never posed to be painted just a fun fact..