uh, was it? I've read different.. basically that people knew about it, but as you say, had no real reason to take that route. But now we have someone deliberately trying to get from east to west, and we have a route that is known. Which also bring up the question of just how well known the ocean currents were known for the north Atlantic... if Columbus doesn't go the Viking route, do people know enough to take the other sailing routes?
Maybe if Columbus goes to the king Copenhagen, he could study old records of Greenland. The explorer Didrik Pining had been in Greenland and possibly Newfundland just a few decades earlier. Records must have existed also in Iceland. Maybe Columbus tries to find a west passage to India through Greneland and then the coast of Markland und Vinland.