information:extraction
Nautical considerations

Though Columbus was wrong about the number of degrees of longitude that separated Europe from the Far East and about the distance that each degree represented, he did take advantage of the trade winds, which would prove to be the key to his successful navigation of the Atlantic Ocean. He planned to first sail to the Canary Islands before continuing west with the northeast trade wind. Part of the return to Spain would require traveling against the wind using an arduous sailing technique called beating, during which progress is made very slowly. To effectively make the return voyage, Columbus would need to follow the curving trade winds northeastward to the middle latitudes of the North Atlantic, where he would be able to catch the " westerlies " that blow eastward to the coast of Western Europe.

The navigational technique for travel in the Atlantic appears to have been exploited first by the Portuguese, who referred to it as the volta do mar ('turn of the sea'). Through his marriage to his first wife, Felipa Perestrello, Columbus had access to the nautical charts and logs that had belonged to her deceased father, Bartolomeu Perestrello, who had served as a captain in the Portuguese navy under Prince Henry the Navigator. In the mapmaking shop where he worked with his brother Bartholomew, Columbus also had ample opportunity to hear the stories of old seamen about their voyages to the western seas, but his knowledge of the Atlantic wind patterns was still imperfect at the time of his first voyage. By sailing due west from the Canary Islands during hurricane season, skirting the so-called horse latitudes of the mid-Atlantic, he risked being becalmed and running into a tropical cyclone, both of which he avoided by chance.