Volta do mar

"Volta do mar", "volta do mar largo" or "volta do largo", (the phrase in Portuguese means literally turn of the sea but also return from the sea) is a navigational technique perfected by Portuguese navigators during the Age of Discovery in the late fifteenth century, using the dependable phenomenon of the great permanent wind wheel, the North Atlantic Gyre. This was a major step in the history of navigation, when an understanding of winds in the age of sail was crucial to success: the European sea empires would never have been established had the Europeans not figured out how the trade winds worked.

The volta do mar was a sailing technique discovered in successfully returning from the Atlantic islands, where the pilot first had to sail far to the west in order to catch usable following winds, and return to Europe. This was a counter-intuitive sailing direction, as it required the pilot to steer in a direction that was perpendicular to the ports of Portugal. Lack of this information may have doomed the thirteenth-century expedition of Vandino and Ugolino Vivaldi, who were headed towards the as yet unknown Canary Islands and were lost; once there, without understanding the Atlantic gyre and the volta do mar, they would have been unable to beat upwind to the Strait of Gibraltar and home. Discovering this technique was crucial for returning from future discoveries; for example Christopher Columbus would never have returned from America without applying the volta do mar by sailing northwards from the Caribbean through the Horse Latitudes to catch the prevailing mid-latitude westerlies.

...
Wikipedia