In the fourteenth and fifteenth centuries, European ships varied in structure because each port in every country had its own tradition of shipbuilding. Most ships belonged to one of two types. The northern ship was called a cog and was square rigged. This means it had a single square sail on a central mast. The square sail helped maneuver well before the wind, but not when the wind was blowing on the side or when the ship was sailing into the wind. The southern or Mediterranean ship was a caravel and lateen-rigged, with big triangular sails on two or three masts. The lateen sail maneuvered well when the wind came from the side, but not when the wind came from behind.

Northern ships were clinker-built with each plank overlapping the next one. Mediterranean ships were carvel-built with planks fitted edge to edge and nailed on to the frame. The carvel hull was larger with sleeker lines to make it move easily in the water. These ships were built entirely of wood, most likely oak. Planks were affixed to the hull with wooden pegs. The walls of the hull could be more than 20 inches thick. The hull was ballasted with gravel to prevent it from rolling over.

The caravel was a combination of centuries of Arab and European shipbuilding techniques. Caravels had similarities to the Arabian dhow in the Indian Ocean. Both vessels shared narrow proportions of length and width, and both had deep hulls and good sailing maneuverability. By the eleventh century, lateen-rigged ships had spread from the Indian Ocean to dominate shipping in the Mediterranean.

In Prince Henry's time, Portuguese ships were displaying attributes from both northern and Mediterranean influences. The Portuguese used a lateen-rigged vessel to explore Africa. Maneuvering along the coast required a great deal of sailing obliquely into the wind or beating against adverse winds. The lateen-rigged caravel excelled in this type of sailing. For long ocean voyages, they used the square sail on the fore and mainmasts, and a lateen sail on the mizzen (the mast at the stern). The square sails filled like parachutes and propelled the ship at maximum efficiency. The slimmer Portuguese caravels had some northern influences from the cog, such as the strong, straight keel or backbone instead of a curved one. Most caravels had two masts and a substantial deck to make it seaworthy and strong enough to carry deck-mounted guns. These ships were no more than 100 feet long with a small poop (a raised section at the stern) containing the captain's cabin.

Longer and longer voyages required bigger ships with more cargo and crew space. Ferdinand Magellan could not have sailed around the world in a caravel. By the end of the fifteenth century, caravels were not commonly used.

Portuguese explorers | Portuguese Ships | Navigation Methods | 15th-century maps & charts