The rise of oceanic navigation began when the basic Mediterranean trading vessel, the Venetian buss (a full-bodied, rounded two-masted ship), passed through the Strait of Gibraltar. At the time of Richard I of England (reigned 1189–99), whose familiarity with Mediterranean shipping stemmed from his participation in the Crusades, Mediterranean navigation had evolved in two directions: the galley had become a rowed fighting ship and the buss a sail-propelled trader’s vessel. From Richard’s crusading expeditions the value of the forecastle and aftercastle—giving enclosed deck houses and a bulging bow of great capacity—was learned, and this style became the basis of the English oceangoing trader. These crusading voyages also introduced the English to journeys longer than the coasting and North Sea navigation they had previously undertaken.

The story of European navigation and shipbuilding is in large part one of interaction between technical developments in the two narrow boundary seas. It is thought that sailors from Bayonne in southwestern France introduced the Mediterranean carrack (a large three-masted, carvel-build ship using both square and lateen sails) to northern Europe and in turn introduced the double-ended clinker ship of the north to the Mediterranean. This cross-fertilization took place in the 14th century, a time of considerable change in navigation in the Atlantic-facing regions of France, Spain, and Portugal.

Changes in shipbuilding during the Middle Ages were gradual. Among northern ships the double-ended structure began to disappear when sailing gained dominance over rowing. To make best use of sails meant moving away from steering oars to a rudder, first attached to the side of the boat and then, after a straight stern post was adopted, firmly attached to that stern. By 1252 the Port Books of Damme in Flanders distinguished ships with rudders on the side from those with stern rudders.

The arts of navigation were improving at the same time. The compass was devised at the beginning of the 14th century, but it took time to understand how to use it effectively in a world with variable magnetic declinations. It was only about the year 1400 that the lodestone began to be used in navigation in any consistent manner.

15th-century ships and shipping

The early 15th century saw the rise of the full-rigged ship, which had three masts and five or six sails. At the beginning of that century Europe and Asia were connected by caravan routes over land. The galleys or trade ships were long, low-sided, commonly rowed for much of their voyage, and guided by successive landfalls with little need for the compass and mathematical navigation. By the end of the century Da Gama, Columbus, and Cabot had made their revolutionary journeys, the Portuguese had organized the first school of oceanic navigation, and trade had begun to be global.

“Full-rigged” ships were introduced because trade was becoming larger in scale, more frequent in occurrence, and more distant in destination. There was no way to enlarge the propulsive force of ships save by increasing the area of sail. To pack more square yards of canvas on a hull required multiple masts and lofting more and larger sails on each mast (as shown in the figure). As multiple masts were added, the hull was elongated; keels were often two and a half times as long as the ship’s beam (width). At the beginning of the 15th century large ships were of about 300 tons; by 1425 they were approximately 720 tons.

In the 16th century the full-rigged ship was initially a carrack, a Mediterranean three-master perhaps introduced from Genoa to England. The trade between the Mediterranean and England was carried on at Southampton largely by these carracks. As the years passed the galleon became the most distinctive vessel. This was most commonly a Spanish ship riding high out of the water. Although the name suggested a large galley, galleons probably never carried oars and were likely to be four-masted.

In earlier centuries ships were often merchantmen sufficiently armed to defend themselves against pirates, privateersmen, and the depredations of an active enemy. In peacetime a ship would go about its business as a nation’s trader, but it was able to become a fighting vessel if necessary. When the size of guns and the numbers involved grew to create an offensive capability, there remained little space to carry the volume of goods required by a trader. What resulted was the convoy, under which merchantmen would be protected by specialized naval ships. The distinction between warship and trading ship might have remained quite abstract had not the theory and tactics of warfare changed. Most medieval wars were either dynastic or religious, and armies and navies were small by modern standards. But beginning with the warfare between the Dutch and the English in the 17th century, conflict was the result of competition in trade rather than in sovereignty and faith. Thus, the major trading nations came to dominate ship design and construction.