Volta do mar

The phrase "volta do mar", in Portuguese, means literally "return through the sea", the navigational technique perfected in the late fifteenth century, using the phenomenon of the great wind wheel, the North Atlantic Gyre, a major step in the history of navigation. 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 — counter-intuitively, in the wrong direction, that is, farther from Portugal — in order to catch usable following winds, and return to Europe. 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 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. The route of the Manila Galleon from Manila to Acapulco depended upon successful application of the Atlantic phenomenon to the Pacific ocean: in discovering the North Pacific Gyre, captains of returning galleons had to reach the latitudes of Japan before they could safely cross. The discovery, upon which the Manila-Acapulco galleon trade was based was owing to Andrés de Urdaneta, who, sailing in convoy under Miguel López de Legazpi, discovered the return route in 1565: the fleet split up, some heading south, but Urdaneta reasoned that the trade winds of the Pacific might move in a gyre as the Atlantic winds did. If in the Atlantic, ships made the "Volta do mar" to the west to pick up winds that would bring them back from Madeira, then, he reasoned, by sailing far to the north before heading east, he would pick up trade winds to bring him back to the west coast of North America. Though he sailed to 38 degrees North before turning east, his hunch paid off, and he hit the coast near Cape Mendocino, California, then followed the coast south to Acapulco. Most of his crew died on the long initial voyage, for which they had not sufficiently provisioned.

The European sea empires would never have been established had the Europeans not figured out how the trade winds worked. More information on this can be found in J.H. Parry's "The Age of Reconnaissance".