 It was in such ships that Christopher Columbus set out on his expedition in 1492; "Santa María" was a "nau" of about 100 tons which served as the flagship and the "Pinta" and "Niña" were smaller caravels of around 15–20 m with a beam of 6 m and displacing around 60–75 tons.Towards the end of the 15th century, the Portuguese developed a larger version of the caravel, bearing a forecastle and sterncastle – though not as high as those carracks, which would have made it unweatherly – but most distinguishable for its square-rigged foremast, and three other masts bearing lateen rig.In this form it was referred to in Portuguese as a "round caravel" ("caravela redonda") as in Iberian tradition, a bulging square sail is said to be round.