Columbus was considered insane because his measurements of the earth's circumference was incorrect. If he never came back people may just assume that the ocean is too big to cross all the way to asia.
If he was considered so insane in his estimates, why did Magellan try a circumnavigation at the time, and why did explorers keep trying to find a northwest passage to Asia up to 200 years later?
The Portuguese would using the winds to swing west on way to India and discover Brazil in and around the same time 1500.
Didn't the Volta Do Mar move mean that the Portuguese approached closest to Brazil on the return leg from India and the Cape rather than the outbound journey to the Cape and India?
I think this map illustrates an important fact to reference, within fifty years after Columbus a majority of America's tropical and temperate shores were charted. By 1542, fifty year after Columbus hit the Bahamas, all of the American coasts from Labrador and the St. Lawrence in the northeast, around Cape Horn and the whole southern continent, and then the west coast of North America up to the latitude of northern California were known to Europeans and charted. Only the Arctic coasts of North America and the Pacific Northwest remained to be discovered after that 50-year spurt.
But this raises the question- did the speed of the initial navigation (which also sponsored permanent and non-permanent colonial efforts every couple hundred miles) depend on the initial landfall being in the Caribbean, so we would expect follow-up to not be so fast if first landfall was in cold Newfoundland, or in Brazil, which some interesting trees but no gold on the coast? Were the coasts explored so fast within fifty years only because the first natives Columbus happened upon had ornamental gold, and then Mexico turned out to have so much?
Or ,would public announcement of a landfall *anywhere* on the American coast, even if there were no gold or rich cities to plunder (like in Newfoundland or Brazil), have caused the Europeans to explore the American coasts so comprehensively, simply because of the Europeans readiness to take risks, the prospect of potential profit from any commodities, or of a another route to Asia, and because navigational tech was up to the task in the late 1400s early 1500s?
Map illustrating OTL's first fifty years of exploration is below: