At Sagres and at the nearby port of Lagos, experiments in shipbuilding produced a new type of ship without which Prince Henry’s exploring expeditions and the great seafaring adventures of the next century would not have been possible. The caravel was a ship specially designed to bring explorers back. The familiar heavy, square-rigged barca or the still larger Venetian carrack was suited for sailing with the wind. These worked well enough within the Mediterranean, where the size of a trading vessel was a measure of its profit, and by 1450 there were Venetian square-riggers of six hundred tons or more. A larger ship meant a bigger profit from more cargo.

A discovery ship had its own special problems. It was not a cargo-vessel, it had to go long distances in unfamiliar waters and had to be able, if necessary, to sail into the wind. An exploring ship was no good unless it could get there and back. Its important cargo was news, which could be carried in a small parcel, even in the mind of one man, but which was definitely a return product, While discovery ships did not need to be big, they had to be maneuverable, and adept at the return. […]

“The Portuguese Discoverers”, from “The Discoverers”, Daniel J. Boorstin, The National Board for the Celebration of Portuguese Discoveries, Lisbon, 1987