So why were the Europeans so successful in global exploration by sea? One of the most common types of ship design used what we might call the roman square rig, one or two masts each carrying a single square of sail and with a single rope on each side to serve as a tack or sheet. This design only worked with the wind abaft of the beam, and if it came from forward direction, ships could only creep out of port under oars. Otherwise they were port-bound. It is well known how Roman ships relied extensively upon the use of oars, with slaves to work them.
The lateen sail is triangular in shape and is the characteristic design of all Arab ships through history. The sail is laced to a long yard hoisted obliquely to the mast, which itself has a forward rake. Perfect for vessels of small and medium size, the lateen rig is thought to have emanated from the Indian Ocean before the birth of Christ. Boats had good manoeuvrability and the design spread throughout the Mediterranean, reaching as far as the Atlantic coast by the eleventh century when Arab presence in southern Spain was dominant.
The lateen rig, however, has a number of serious limitations, the main one being that it is hard to bring about. This makes its use in large vessels extremely impractical and limited the degree to which Arab navigation was able to develop. Arab vessels were frequently limited by too little canvas and therefore very slow. This, in turn, made long journeys impractical and arduous. Thus, the Arabs, though good seamen, had to rely upon coasting for their movements and did not use or develop lighthouses.
Ships that needed many men to operate them were naturally inefficient. It was necessary to carry lots of provisions, or else to call into port very often to re-supply. They were also unable to carry large quantities of cargo because too much space was taken up with men and materials for the voyage. A fourteenth century lateen ship carrying 250 tons of cargo required some fifty men to sail it, whilst a similarly laden square rigged ship required only twenty. This fact alone offered a significant commercial advantage to the owners of square-rigged vessels. By 1400, square rig had been adopted for large, slow but capacious ships throughout the Mediterranean area.
Ships designed and built from the Baltic to Galicia were altogether different from their Mediterranean-designed counterparts. They had straight keels and overlapping planks, a style known as clinker-built. Both of these features made them much stronger and better able to cope with strong currents, tides and occasional groundings. They had sternposts with rudders hung on pintles for better steering, but counteracting this was their tendency to be wide in comparison to their length. The main improvement in northern-designed ships was made in the rig. Sails remained square, but were better hung and controlled. These improvements took time to develop, but such a boost to the ships capabilities was achieved that this enabled the Age of Reconnaissance, the world discoveries initiated from Europe during the 15th century . Designs also included features to enable the ships to be successful in battle. This too was to prove a significant advantage over potential enemies such that the Europeans were able to gain the upper hand over the Arabs and to dominate the exploration (and exploitation) of Asia, Africa and America.