On Nov. 27, 1095, Pope Urban II called upon Christendom to deliver the Holy Land from the Arabs, Saracens and Turks who had held it since the 7th Century. While the Holy Wars failed to restore Christian sovereignty to Jerusalem, they did set the stage for a series of nautical innovations that changed the course of history.
Ocean travel had been possible since 1000 BC, when Phoenician traders in the eastern Mediterranean discovered that a keel gave stability to a ship under sail. But neither they nor the Greeks, Romans and Vikings who followed fully mastered the technique of sailing to windward.
For more than 2,000 years, merchant ships sailed in one general direction--downwind. That began to change in 1189, when knights of the Third Crusade sailed into a Mediterranean bustling with a ship theretofore unseen: the lateener. Named after the Latin countries where they were found, lateeners did not have a square sail suspended from an upright mast. Instead, they were powered by a huge triangular sail that hung from a yardarm tied to a mast raked toward the bow. Because it could sail to within 45 degrees of the direction of the wind, a lateener could zigzag, or tack, into a stiff breeze.
Range was still limited because the rudder was positioned on the starboard quarter. A ship that tilted to port due to the force of the wind could lose maneuverability if its rudder lifted out of the water. Vessels tended to be small, because the size of a side-mounted rudder had to increase in proportion to the size of a ship.
About 1300, Mediterranean merchants began losing cargoes to Basque pirates in ships with stern-mounted rudders. Venetian shipbuilders quickly realized that a vessel with a stern rudder could grow in size, yet remain maneuverable.
With stern-mounted rudders and lateen rigging, ships began exploring the oceans. But who would discover whom? In many respects, Chinese mariners were more advanced. The batwing sails of a Chinese junk have advantages similar to lateen rigging, and by the late 11th Century even the lowliest fisherman on the China coast had a compass. What the Chinese lacked was a keel: Junks, designed for the riverine commerce and archipelagoes of Southeast Asia, often foundered in the open sea.
In 1275 Marco Polo reported that the Chinese prepared for a rough voyage by sending the weakest sailor aloft in a kite just before departure. If the kite flew, the ship left on schedule. A crash meant bad luck, and the junk remained in coastal waters until the following year.
Exploration began in the 15th Century with the coming of Portuguese caravels, which had three masts and 8 to 10 sails. The ship running before the wind drew power from its square-rigged mainsail. Lateen sails fore and aft allowed it to beat upwind. Prevailing winds off the west coast of Africa had carried the Portuguese south for generations; caravels gave them the ability to sail home with a minimum of effort.
Caravels carried Vasco da Gama to India and Columbus to the Americas. Their rigging allowed Magellan to circumnavigate the globe, and their speed broke Venice's grip on trade with India and the Middle East.
With the defeat of the Spanish Armada in 1588, control of the seas passed to the British and Dutch, who built East Indiamen--enormous vessels that carried 1,000 tons of cargo. The merchant freighters were designed with a "cod's head and mackerel tail" shape that gave them a bluff bow and a narrow, fin-like stern. European shipbuilders thought they had borrowed nature's perfect design. But in reality, East Indiamen were lumbering vessels that seldom traveled faster than four knots.
The decline of British sea power probably began with Parliament's insistence that all colonial trade be carried by East Indiamen. The intent was to make tax collection easier, but instead it inspired Baltimore shipyards to design the frigate, a narrower, faster vessel that quickly became the ship of choice among smugglers. The demand for faster ships led in 1840 to the creation of the clipper ship.
American clippers reduced the sailing time between China and New York from months to weeks. Powered by up to 60 sails, a narrow clipper could travel 250 miles a day.
The clipper came into its own when China, defeated in the first Opium War, agreed to open five mainland ports to foreign trade. The British maintained their opium monopoly, but trade in silk and tea could be cornered by merchants with the fastest ships.
By 1850, oceangoing steamers that had been introduced as early as 1810 began to challenge the clippers. In 1880, steamers finally passed the clippers in speed, but they did not reduce the influence of sail power.