Ships Through the Ages
	The ship of today is a large, sturdy, self-propelled vessel in which people transport goods across seas, oceans, and lakes. It is the product of countless centuries of development. To cross small bodies of water, primitive peoples used any available materials that would float. Early forms of the boat included rafts of logs or bamboo, bundles of reeds, air-filled animal skins, and even jars and asphalt-covered baskets.
	The First True Boats
	Among the first true boats was a fairly simple frame of sticks, lashed together and covered with sewn hides (a joint in a ship's hull is still called a seam). Such boats could carry substantial loads. Another early boat was the dugout, a log hollowed out and pointed at the ends. Dugouts ranged up to 60 feet (18 meters) in length.
	Paddles, Poles, Oars, and Sails
	People propelled the earliest inflated skins by paddling with their hands. Poles, pushed against the bottom, moved rafts in shallow water. Widened and flattened at one end, the pole became a paddle for use in deeper water. Later came the oar a paddle pivoted on the side of the boat. The sail was one of the great inventions in history. It let the strength of the wind replace the action of human muscle, although for many centuries ships often combined the sailing power of wind with the strength of rowers. While rowboats could carry little more than a few days' food supply for the oarsmen, sailboats could make long trips with payloads. Early sailing vessels carried square sails, which were best suited for sailing downwind. Fore and aft sails, better suited for tacking to windward, came later. Dugouts were not wide enough to carry sail without capsizing. Ultimately they were stabilized with outriggers floats attached by long poles to one side. In such canoes the Polynesians ranged thousands of miles across the island chains of the Indian and Pacific oceans.
	Ships Assembled from Small Parts
	The early Egyptians developed advanced sailing cargo ships. Lacking the great trees needed for large dugouts, they built their ships by lashing and sewing together small pieces of wood. Such ships could transport great columns of stone, weighing up to 350 tons, for use in monuments. Egyptian ships also traded across the Mediterranean and Red seas. A dugout could be built with stone tools and the aid of a fire to hollow the log. The invention of metal tools provided means of shaping logs into timbers and splitting or sawing timbers into planks. With these, builders enlarged their dugouts. They fastened upright timbers to the inside of the dugout, extending them above its sides. To these they attached lengthwise planks. They caulked, or filled, the seams between the planks with pitch and fiber. Too little evidence has survived from prehistoric times to determine who developed the planked wooden ship. Among the earliest of such ships, however, were those of the Phoenicians. It is probable that the Phoenician ships of some 2,500 years ago were constructed much as were the wooden sailing vessels of later centuries. In the hands of the Phoenicians, the log of the dugout became a lengthwise keel of sturdy timbers. Uprights a stempost at the front and a sternpost at the rear rose from the ends of the keel; between these, curved frames, or ribs, rose at right angles to the keel. Planks with caulked seams covered this framework. Sails and oars provided power. With such galleys, built of Lebanon cedar, the Phoenicians dominated Mediterranean commerce for centuries. As galleys grew larger, rowers were arranged on two levels. Such craft were called biremes by the Greeks and Romans, who also built triremes galleys with three banks of oars. The ships of northern Europe are the best known of the period around AD 1000. Several well-preserved Viking ships have been dug up. Three are displayed in an Oslo, Norway, museum. Open, with high, pointed bows and sterns, they were built of oak planks that overlapped like shingles. Such construction, called clinker building, remained standard for large ships of northern Europe until after 1450. Both sails and oars propelled the Viking ships, which were steered with an oar fixed to the starboard ("steerboard"), or right, side. The left side is port. Later ships were covered with decks. For defense, platforms for archers were built at the ends. Eventually these fore-castles and after-castles were incorporated into the hull structure; the raised forward part of a ship is still called the forecastle (fo'c'sle). The rudder, hinged on the sternpost, replaced the steering oar in about 1200.
	Ships of the Age of Discovery
	The smooth-planked construction technique called carvel building after the Mediterranean carvels in which it was first employed reached northern Europe about 1450. At about the same time, ships began to carry as many as three masts. In the middle was the largest (main) mast, which carried a square sail. A smaller fore mast near the bow also carried a square sail. A mizzen mast, near the stern, carried a fore-and-aft sail. Soon another sail was spread beneath the bowsprit, which extended forward from the bow, and smaller topsails were set above the mainsail and foresail. Christopher Columbus, Vasco da Gama, and other explorers of their time sailed in ships so rigged. Wooden ships, carvel-planked over frames, were built all over the world by European settlers. The woods most used were the oak of England and northern Europe, the live oak and white oak of eastern North America, and the teak of India. The white pine of New England and the Douglas fir of the Pacific Northwest were highly prized for masts. Wooden sailing ships reached their highest level of development between 1840 and 1905. Notable ships of the period included the wooden walls of the sailing navies, the clippers which brought gold prospectors to California (Perspective View [43 KB]) and Australia, the Down Easters built in Maine for trade with California, and the five-and six-masted schooners which carried coal from Virginia to New England.
	Wood Yields to Iron
	Meanwhile iron gradually began to supplant wood in ship construction. Although used experimentally by the British before 1800, iron did not become a significant shipbuilding material until after 1830. By 1855 it was displacing wood in British shipbuilding. The new technology soon spread to other nations. Composite sailing vessels with planks of wood over iron frames were popular for a few years, especially in the tea trade between China and Britain. Since copper is poisonous to marine growths, wooden hulls were often covered with thin sheets of copper to prevent the accumulation of barnacles, which otherwise would cling to the hull and reduce speed. No method had been devised for keeping iron hulls free of barnacles except scraping them off periodically. Iron hulls could not be covered with copper, for, in salt water, electrolysis between the iron and the copper soon destroyed the iron. After the opening of the Suez Canal in 1869, however, iron-hulled steamships could travel from Europe to China in a few weeks. They could be dry-docked and cleaned often enough to eliminate fouling as a major problem.
	Steam Supplants the Sail
	Although the greatest of the sailing vessels the long, steel-hulled windjammers of the late 19th and early 20th centuries were yet to come, the end of the sailing vessel of commerce was already in sight. The transition was from "wooden ships and iron men to iron ships and wooden men," said the old sailormen, irked by the change. There had been many experiments with steam-powered vessels in the 18th century, but the first commercially successful steamer was Robert Fulton's North River Steamboat of 1807. It is better known today as the Clermont, after its home port of Clermont, N.Y. Henry Bell, a Scot, built the first successful British steamboat in 1812. Within a few years, steamboats plied protected waters throughout Europe. As accessible forests were depleted, coal replaced wood as fuel.
	Steamships in Ocean Trade
	The Savannah, a sailing ship fitted with a steam engine, crossed the Atlantic Ocean in 1819, but the ship was not a commercial success. Its eastward run required 29 1/2 days and was made mostly under sail limited fuel permitted use of the engine for only 80 hours. Regular transatlantic steamer service was begun by British firms after they had gained experience by operating steamships around the British Isles. Two wooden liners, the Great Western and the Sirius, inaugurated transatlantic passenger service under steam in April 1838. The two reached New York City within one day of each other. The Sirius was 15 days out of Cork, Ireland; the Great Western the first steamer built expressly for transatlantic service had taken 18 days from Bristol, England. It was many years before steamships could equal the records set by sailing ships, but they were independent of the wind and on the average could make faster passages. The clipper ship James Baines once made the run from Boston, Mass., to Liverpool, England, in a record 12 days 6 hours, but sailing packets usually required about three weeks to make an eastbound crossing of the Atlantic and four to six weeks or more for a westbound crossing. In the Britain-to-Australia trade, steamers could make two or three round trips (voyages) per year, while clippers could make only one. Most early steamships were driven by paddle wheels, but in about 1840 Francis P. Smith of England and the Swedish-American inventor John Ericsson developed screw propellers. The first iron-hulled steamer with a screw propeller to enter transatlantic service was the Great Britain, in 1845. Early ocean steamers also carried sails, for not until about 1880 were steam engines fully reliable. Sailing packets continued to carry passengers until the 1860s, but steamships soon dominated the transatlantic passenger trade. Governments subsidized steamship companies to ensure that, in case of war, their nations would have fleets of fast steamers to use as troopships and auxiliary cruisers. Cheap steerage accommodations in the swift steamships encouraged hundreds of thousands of people to emigrate from Europe to North America. In a sailing ship, immigrants had to provide food for themselves and their families for 40 to 60 days. Traveling by steamer, they could be looking for work in New York City or Montreal, Que., within two weeks.
	Advances in Engines and Construction
	Steam engines continually grew more reliable and more efficient. Compound engines were introduced in about 1870; triple- and quadruple-expansion engines followed. Each consumed less coal per unit of power, thus freeing space for cargo. Steamers with compound engines could compete with sailing ships in almost any branch of trade, and tramp steamers, which picked up cargoes when and where they could, became common after 1870. By about 1887 the world's steamships exceeded sailing ships in tonnage. The total tonnage of sailing vessels reached a peak of about 9 million in 1892; since then, it has steadily declined. Steamship and motor-ship tonnage, on the other hand, has increased more than tenfold since 1892. Around the turn of the century, the steam turbine was adapted to ship propulsion by Charles Parsons of England. Experiments with petroleum for fuel had been made before 1900, and in 1902 steamers on the United States West coast adopted oil as fuel. Its use spread rapidly because oil-burning steamers needed fewer men in the Engine Room pumps, not men with shovels, handled the fuel. Diesel engines, which today power 99.7 percent of new ships, were first used on seagoing vessels in 1912. Powerful modern marine diesels are designed to run on low-grade, low-cost fuel oil. An increasingly popular form of propulsion is the diesel-electric system, in which diesel engines are linked to generators. The electricity produced is fed to large electric motors that drive the propeller shafts. Hand-driven rivets joined the plating and other structural members of the first iron and steel ships. Later, hydraulic and pneumatic tools applied rivets with greater force. After 1930 electric welding was introduced for joining hull members. During World War II welding almost completely replaced riveting in the construction of merchant ships.
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