Medieval ships were powered by sail, or oar, or both. There were a large variety, mostly based in much older conservative design. Although wider and more frequent communications within Europe meant exposure to a variety of improvements, experimental failures were costly and rarely attempted. Ships in the north were influenced by Viking vessels, while those in the south by classical or Roman vessels.
In Europe, the Viking-style longship, which was clinker-built, was later replaed by the Knarr, a type of cargo vessel, which had no oars, but relied solely on a square-rigged sail. The Knarr was replaced by the Cog, which was in wide use by the 12th-century. Following the Cog came the Caravel Latina and then the Caravel Redondo. The uniqueness of the Caravel was that it could use the lateen sail (Latina) or square-rigged sailes (Redonda). Invented in Moorish Spain in the 13th century, the ship was the first to sail far off shore, the one the Portugeuse used to sailed around Africa, and the design of Columbus’ Nina and Pinta.
The reason for the caravel’s early dominance is simple. A square-rigged ship performs splendidly when running before a wind; its sails fill like a parachute and it is propelled forward with maximum efficiency. But the close coastal sailing demanded during Portugal’s African expeditions involved a good deal of sailing obliquely into the wind, or beating against adverse winds. Here is where square-rigged ships acquitted themselves dismally, and where lateen-rigged caravels excelled. While a square sail pushes a ship before the wind, a lateen sail pulls the vessel along. The lateen behaves more like a wing than a parachute.
When Nephi says he was blown forth before the wind, it is this exact principle of a square rigged sail that is blown forward, its sail filling like a parachute and running with the wind. Such would be possible where the wind blew toward the land of promise, such as in the Prevailing Westerlies south of Australia, New Zealand, and out into the Pacific. However, it would not be possible to be blown before the wind on a journey through Indonesia and then east across the Pacific against the wind currents.
In addition to other advantages of the Caravel, it had a shallow draft, six feet or less, in most cases, which is ideal for investigating or running close to a shoreline. With their fully rigged lateen sails, one fore and the other aft, they were ideal high-maneuverable vessels used for short mercantile runs along the coasts of the Mediterranean, and for the exploration of coastal waters along the Africa coast. However, when Dias experienced heavy buffeting when he got out into the deeper water off the coast of Africa, and when called upon to design ships for Vasco da Gama’s expedition, he chose three stout square rigged vessels, the flagship São Gabriel, the São Raphael, and a storeship whose name has been lost to history. These square-rigged ships were ideal to brave the deeper ocean and when Da Gama swung far west of the African coast to avoid coastal squalls and currents, he picked up the westerlies which propelled him around the Cape of Good Hope.
These are the same westerlies that would have propelled Nephi’s ship across the Pacific when it was driven forth before the wind. Obviously, it would have been square rigged, for square-rigged ships are far better design for sailing before a wind, as Nephi stated.
Not until the opening of long-distance trade routes begin to require lengthy, open-ocean voyages within predictable patterns of sustained winds, did these mixed fore-and-aft square rigging and lateen mixture sailing ships come into their own. Such square rigging was necessary for deep ocean sailing, as well as a deep hull design with ballast to keep the ship from toppling in high winds and waves. The typical coastal vessel often quoted by Mesoamerican Theorists using an Indonesian approach to the Pacific were much shallower vessels and would have been beaten to puplp sailing across the deep waters of the Pacific.