Complex sentence: The voyages were made in very small ships, mostly the caravel, a light and maneuverable vessel that used the lateen sail which had been the prevailing rig in Christian Mediterranean navigation since late antiquity.
Split into simpler sentences: The voyages were made in very small ships, mostly the caravel, a light and maneuverable vessel. The caravel used the lateen sail, the prevailing rig in Christian Mediterranean navigation since late antiquity.