For nearly 800 years, European ships kept the clinker-built hull of overlapping lanks and square sail known to the Vikings. By the thirteenth century the stern and bow has been built up into “castle” structures, and the stern-mounted rudder had replaced the steering-oar.
By trading with the Mediterranean, northern builders learned of the “Carvel” structure: a skin of planks fitted edge to edge over an internal frame. They also learned how the triangular lateen sail made it easier to sail close to the wind. By about 1450 the one-masted, clinker-built European cog of the past 200 years has given place to the carvel-built, three-masted carrack.
The Arab world in the middle ages produced some of the greatest shipbuilders and sailors of all time. Arab lateen-rigged, two-masted dhows, navigated by the stars, sailed as far afield as southeast Africa and China. Remarkably, Arab shipbuilding used no nails: the timbers were stitched and lashed together with coconut fiber. In 1980-81, Tim Severin built an authentic Arab dhow and sailed it from Muscat, Oman, to china in seven and a half months.
Pacific Islanders, in big, double-hulled canoes driven by “crab-claw” sails, also steered by the stars on voyages over 4,800 kilometers (3,000 miles), cruising the Pacific Ocean from Hawaii to New Zealand. The most advanced Asian ships in the Middle Ages were the Chinese junks recorded by Marco Polo in the thirteenth century. The biggest had five masts, 60 passenger cabins, and watertight compartments to limit the danger of flooding. The big sails were stiffened with bamboo slats.