Ship. I INTRODUCTION Ship, vessel that is buoyant in the water and used

Ship. I INTRODUCTION Ship, vessel that is buoyant in the water and used to transport people or cargo from one place to another via rivers, lakes, or oceans. Traditionally, ships were distinguished from boats by size--any buoyant vessel small enough to fit on board a ship was considered a boat. However, common usage has blurred the distinction between boats and ships, and today the difference between them is arbitrary. From prehistoric craft made from animal skins stretched over wooden frames to nuclear-powered aircraft carriers that transport 5,000 people and 85 airplanes, ships have always reflected the values and technologies of the societies that built them. Ancient traders of the Mediterranean built swift-sailing ships with large cargo holds. Their warring successors added oars to increase maneuverability in battle. The Spanish and Portuguese built small, seaworthy craft to carry their best sailors to new lands, then huge merchant vessels to haul the newly claimed riches, and finally fleets of warships to protect their growing wealth. At the end of the 16th century, shipbuilders changed their focus to passenger service as they sought to accommodate the increasing number of people immigrating to Australia and the Americas. They shifted from sail power to steam power and built ships that crossed the ocean in about one-fourth the time of their predecessors. When the jet airplane drastically reduced ship travel in the 20th century, shipbuilders again focused on the transport of cargo, turning out large tankers, the most massive ships ever afloat. Despite their seemingly endless variety, all ships share a few basic elements. All ships have a main body, or hull, capable of displacing an amount of water equal to or greater than its own weight and the weight of its cargo. At the front end of the hull is the bow (or prow), and at the rear end is the stern. A ship's size is expressed in terms of the dimensions of its hull--that is, its length, breadth, and volume in tons (calculated by dividing the cubic footage of the hull by 100). All ships also have a steering system and a propulsion system--that is, a device or system of devices that moves them through the water. Like ships themselves, hulls, propulsion systems, and steering systems grew more complex through time. II THE EARLIEST SHIPS Historians surmise that the earliest ships appeared around 16,000 BC in Europe, and perhaps earlier in Asia and Africa. Little archaeological evidence for these prehistoric vessels survives because they were made from perishable materials. Prehistoric drawings illustrate that reindeer hunters of central and western Europe made hulls of animal skins sewn together around a birch wood frame, and archaeologists have discovered vessels made from skin and reindeer antlers dating from 9000 BC. Seal hunters plied the frigid waters of the northern Atlantic in boats constructed from sealskin stretched over frames of wood or whalebone. Ancient peoples used coracles, round, skin-covered vessels with wicker frames, to fish the lakes and rivers of what are now Ireland and Wales. Larger but similarly constructed currachs could sail the open waters of northern Europe. Hunters and fishers all over the world constructed similar hulls from birch bark, balsa wood, papyrus, ox hide, and other local materials. The skin boat was followed by the dugout, a simple hull made from a hollowed out tree trunk. The oldest known dugout dates from about 6000 BC and was discovered in what is now The Netherlands. Technical advances in dugout design appeared shortly thereafter. Ancient boat builders hollowed through the stern of the vessel, then inserted a separate piece of wood, called a transom, to make the craft watertight. They widened dugouts by splitting the hollowed trunk and inserting a plank between the two pieces. They lashed planks to the sides to gain additional height. Many ancient shipwrights embellished their craft with animal heads, beginning the long tradition of decorating and distinguishing a vessel with a figurehead. III SAILING VESSELS Sailing vessels harness the energy of the wind to propel their hulls through the water. They catch the wind in sheets of cloth or fiber, called sails, suspended from wooden or metal poles called masts. The invention of the sail revolutionized the ship and dominated the course of ship construction until the 19th century. A Earliest Sailing Vessels The earliest representation of a ship under sail appears on an Egyptian vase from about 3500 BC. Early Egyptian sailing vessels consisted of a wooden framework covered with papyrus reeds or wood lashed together with rope. Large trees did not grow in the region, so Egyptians imported timbers from nearby Lebanon or lashed small wood blocks together and secured them with pegs. The wood swelled when submerged, forming a nearly watertight seal. Smaller sailing vessels harnessed the wind with two sails. Larger Egyptian sailboats captured the wind with a single square sail and were steered with two steering oars mounted on the stern. Maritime historians know a good deal about ships of this period because the Egyptians sometimes buried pharaohs with ships to transport them in the afterlife. One such funeral ship was unearthed in 1954 during excavation of the Great Pyramid of Giza. This ship was constructed for the pharaoh Khufu, also called Cheops, around 2600 BC. Remarkably well preserved, it was constructed from wood planks and timbers and measures approximately 38 m (125 ft) long. Historians learned a great deal about Egyptian shipbuilding techniques from this vessel, which has come to be known as the Cheops ship. The most able shipbuilders of ancient times were the Phoenicians. They constructed merchant vessels capable of carrying large cargoes between the colonies that rimmed the Mediterranean Sea, such as Carthage in North Africa and Cádiz in Spain. Phoenician merchants built hulls from sturdy wood planks and partially covered them with a platform, or deck, that protected the crew and cargo from weather and ocean spray. Merchant ship design steadily improved, enabling the Phoenicians to navigate beyond the Mediterranean Sea as far as the British Isles and the Canary Islands. B Galleys Competition for dominance in maritime trade between the Phoenicians and the neighboring Greeks led to frequent skirmishes at sea. Finding their merchant vessels clumsy and unresponsive in battle, the Phoenicians developed the war galley, an oared vessel that could maneuver and attack when there was little or no wind to drive the sails. The Phoenicians built the galley from wood planks or blocks and equipped it with one or two removable masts. They traveled under sail power on long hauls between ports but lowered the mast and sail and switched to oar power for battles. Oars permitted warriors to easily maneuver the ship within arrow-shooting or javelin-tossing range of enemy ships and just as easily retreat when enemies threatened them. Galleys proved versatile enough for use in both trade and war. In the 9th century BC the Greeks armed the galley with a ram, a sharp spike that extended forward of the ship below the waterline. Encased in bronze, the ram could be driven into an enemy vessel to disable or sink it. This addition transformed the galley into a weapon, not just a carrier of warriors who fought at sea. Shipbuilders soon learned that galleys capable of generating short bursts of speed could catch and ram opponents more effectively. They constructed longer ships or reconfigured the designs of smaller ships to accommodate more oarsmen. The penteconter, or fifty-oared galley (25 oars per side), became the most popular choice for naval warfare. It allowed for about 1 m (3 ft) of space for each oarsman, featured decks at the stern and bow, and measured about 30 to 38 m (100 to 125 ft) in length. B1 Biremes Experience soon proved that longer ships posed a new set of problems: They were weaker structurally, more difficult to maneuver, and presented a larger target to any enemy ship with a ram. In the 8th century BC Mediterranean shipbuilders eliminated these problems with the bireme, a war galley built to accommodate two levels, or banks, of oarsmen. Oarsmen on the lower level rowed oars from ports cut into the side of the vessel, while those above rowed from the deck. This arrangement allowed more men to power the bireme without lengthening the ship. B2 Triremes The search for even greater power at sea resulted in the creation of the trireme, a galley with three banks of oarsmen. These very expensive vessels carried as many as 170 oarsmen and dominated the Mediterranean from the 6th century to the 4th century start of the Peloponnesian War (431-404 BC), BC. Athens invested heavily in triremes and had the finest navy afloat at the a struggle for power between Athens and Sparta. Athens's naval dominance proved temporary, however. In 404 BC incompetent Athenian admirals lost the fleet and the war. The problem with oared vessels was they could not carry sufficient food or water to sustain their crews long at sea. So the admirals ordered the galleys beached and sent the crew ashore for food and water. While the crew was away, Spartans attacked and destroyed the once mighty Athenian fleet. B3 Roman Galleys By the time ancient Rome rose to power, the trireme had lost its position as the dominant war vessel. Dionysius the Elder, the aristocratic ruler of Sicily, built a navy of about 300 vessels that featured quadriremes and quinqueremes. Historians doubt that these ships had four and five banks of oarsmen, as their names suggest. Instead, it is believed four to five men worked together to row each oar. These ships often carried 100 fighting men and either a stone-throwing catapult to attack port towns or bowed catapults that fired darts or stones. The Roman navy also came to rely on Liburnian galleys, small, two-level ships known for their speed. The navy protected Roman merchant ships from enemies and pirates. The sophisticated merchant ships were large, high-sided vessels with two or three masts that flew square sails. Many measured 500 tons, and historians theorize that special ships used to transport Egyptian grain to Roman territories exceeded 1,000 tons. No examples of the grain transports have been recovered, however. Roman galleys and merchant ships dominated the Mediterranean until the Western Empire broke up in the 5th century B4 AD. Dromons As the Western Roman Empire fell to Germanic tribes and its own internal problems, the Roman Empire in the east, called the Byzantine Empire, flourished. The Byzantine navy transported soldiers and supplies to help recover the Western Empire. The navy relied on fast galleys called dromons, or racers, to accompany and protect the supply ships. Early dromons had a single bank of oarsmen, but Byzantine shipbuilders later incorporated a second level for oarsmen. C Lateen-Rigged Ships In the 7th and 8th centuries AD, Arabs, inspired by their new religion, Islam, repeatedly attacked Byzantine ports. Substantial changes in ship construction began to appear in the eastern Mediterranean, due in part, historians suspect, to exposure to Arab ships and seafarers. One such change was the adoption of lateen sails, previously used on Roman coastal vessels, but later seen on Arab sailing ships called dhows. Triangular in shape, lateen sails enabled a vessel to sail almost directly into the wind--a feat not possible with square sails. Byzantine dromons appeared with Arab-influenced lateen rigging by the 6th century, and by the 9th century the square sail had all but disappeared in the Mediterranean and farther south. Shipbuilding techniques also changed in this period. Instead of building with the traditional shell-first construction, in which the builder joins planks tightly with fasteners to form the ship's hull, shipwrights began building a skeletal framework first, then fixing the planking to the frame. Evidence from an 11th century shipwreck found in present-day Serçe Liman, Turkey, exemplifies the typical changes. This small coastal freighter supported two masts carrying lateen sails, and the frame was clearly constructed first. D Junks In China and other areas of Asia, shipbuilders had developed an entirely different, and many argue superior, sailing ship. The junk was a wooden, ocean-going vessel recognized for the ingenuity with which it was developed and its remarkable seaworthiness. The flat-bottomed craft was assembled on a bed of sandbags, which settled and shifted as they adjusted to suit the craft's growing weight. Junks have high sterns and square bows, and most carried four or more masts that sported sails made of fiber and later, of small pieces of cloth. The sails were stiffened with bamboo battens to improve their efficiency. Asian shipwrights made innovative use of bulkheads to strengthen the hull. These partitions also created a number of watertight compartments that enabled merchants to carry liquid cargo. Instead of using side oars for steering, junks had a hinged plate at the stern called a rudder, a technological innovation not regularly seen in European ships until about the 12th century. By the 9th century, Chinese junks regularly plied coastal and open waters of China, Japan, and Southeast Asia, and by the 15th century, junks regularly traveled as far as East Africa. Among the junk's most famous accomplishments were the journeys of Chinese explorer Zheng He, who, between 1405 and 1433, made seven voyages across the Indian Ocean, the Arabian Sea, and the Red Sea commanding a fleet of about 200 junks. A kindred vessel was the lorcha, which had a European style hull but was rigged with the sails of a junk. E Viking Ships In northern Europe, Scandinavian shipbuilders had been practicing a unique construction technique since the 4th century BC. They constructed a vessel by laying a wooden backbone, or a keel, then attaching successive overlapping strakes (planks) until a hull was formed. After finishing the hull, the Scandinavians inserted a skeletal framework to strengthen and support the vessel. This building method, called lapstrake, is unique in that each run of planking overlaps the one below it. Shipwrights used iron fasteners, or clinch bolts, to hold the double thickness of planking together. From the word clinch, this form of building also became known as clinker building. By the 8th century AD, Nordic peoples called Vikings regularly traveled in clinker-built vessels designed for trade, transport, and warfare. Viking longships with 80 oars or more and a single removable mast with a square sail carried warriors into battle. The sailors lowered and stored the mast when traveling under oar power. Longships had a shallow draft, a design that enabled Vikings to navigate rivers and streams. This design permitted them to take many inland settlements by surprise because the inhabitants did not expect an attack from the water. The Viking ship had no deck and offered its crew little protection from the wind and water. Nonetheless, the Vikings traveled great distances in their ships. They traded and raided along the northern seas, founded Dublin in Ireland, conquered much of England, invaded France, and descended the rivers of eastern Europe as far as Kiev and Constantinople. Norse Vikings led by Leif Eriksson sailed west to Greenland, Iceland, and Vinland (probably present-day Newfoundland and Labrador) in North America. Historians know a good deal about these ships because the Vikings, like the ancient Egyptians, sometimes buried important members of their communities with ships. In 1904 archaeologists found the remains of an early 9th-century ship while excavating a Viking burial mound located on a farm near Oslo, Norway. The ship, which has come to be known as the Oseberg ship for the farm on which it was found, has a 22-m (71-ft) clinker-built hull with an elegantly curved bow and stern. It had a single mast and accommodated 30 oars. The ancient shipwright had used baleen, or whalebone lashings, to fix wooden supports to the hull. The similarly constructed Gokstad ship was discovered in a burial mound in Norway in 1880. Built about 850, this ship had a single mast that supported a square sail. It was 24 m (78 ft) long, with a breadth, or beam, of about 5 m (17 ft), and it was steered with a steering oar controlled by a wood bar called a tiller. In 1893 enthusiasts built a replica of the Gokstad ship and sailed it from Bergen, Norway, to New York, New York. Similar replicas have crossed the Atlantic Ocean several times. F Cog In the 11th century the Viking's stronghold in northern Europe began to slip. As their reign of terror subsided, maritime trade resumed in northern Europe, and with it arose the need for sailing vessels capable of transporting large cargoes. By the 13th century the cog had taken its place as the major cargo vessel in northern Europe. Developed over many centuries, the cog was clinker-built like Viking ships. It had a flat bottom, high sides, and a large carrying capacity. The flat bottom was constructed of planks fit edge-to-edge. As the sides of the hull rose, the planks overlapped each other in clinker-building fashion. Cogs had one tall mast that carried a single, square sail, and elevated decks at the bow and stern. The raised structures at the bow, called the forecastle, and the stern, called the sterncastle, permitted sailors to hurl stones or spears and to shoot arrows downward at other ships. The cog's steering system consisted of an innovative rudder, attached like a hinge at the center of the stern and controlled by a tiller. This revolutionary control system remains the standard on ships to this day. From the 13th to the 15th century, the cog dominated trade between the Baltic Sea and the North Sea ports of the Hanseatic League, an alliance of merchants and cities in northern Europe. Until 1962 almost all of what maritime historians knew of cogs came from the official seals of Hanseatic towns and their coins. Archaeologists excavated a 14th-century cog in Bremen, Germany, in 1962. The ship measured 23 m (77 ft) and could carry 130 tons of cargo. In the 15th century the cog gave way to the hulk, a similarly constructed large sailing vessel characterized by a single mast and a rounded bow and stern. G Carrack By the end of the 15th century, both the cog and the hulk had lost their popularity to the carrack. Probably first built on the Atlantic coast of Europe, the carrack blended elements of Mediterranean and northern European ship design. The shipwright first built a skeletal frame, to which he fixed planks edge-to-edge and caulked between them to form a smooth finish. Planked hulls with this type of construction, called carvel-built, contrast with the overlapping planked hulls of clinker-built ships. The carrack sported two, and later three, masts. The fore and main masts carried square sails; the after, or mizzen, mast carried a lateen sail. Sail area, and therefore ship speed, was increased by flying topsails above the main sails. The elevated forecastle and sterncastle housed the crew and passengers and protected them from rough weather. Carracks were commonly used for trade and war in the Mediterranean and northern seas. In 1510 King Henry VIII of England built the 32-m (105-ft) battle carrack Mary Rose and equipped the ship with what was then state-of-the-art artillery. On previous ships, fighters stood on elevated decks to fire cannons and other weapons down onto the decks of enemy ships. Mary Rose featured gun ports with hinged lids on each side. During battle, fighters opened the lids, rolled out the cannons, and fired at the enemy ship's hull instead of its deck. Though convenient, gun ports also proved vulnerable. If the gun ports were cut too close to the waterline, water could pour into the ship and sink it if it listed to one side. The Mary Rose, which sank in 1545, probably met this fate. Attempts to salvage the cannons and other valuables onboard proved more or less futile. The ship was forgotten until the 1970s, when marine archaeologists found it on the ocean bottom and began to bring its thousands of artifacts to the surface. The ship itself was raised in 1982. H Caravel Fishing vessels called caravels first appeared in Spain and Portugal in the 13th century. These small, seaworthy sailing ships proved so agile and reliable that almost every European seafaring nation had adopted them by the end of the 15th century. Caravels carried cargo of all kinds throughout the Mediterranean, Atlantic, and Indian oceans and became a favorite of Portuguese and Spanish explorers. Caravels were carvel-built--that is, constructed frame-first and covered with planks fitted flush to one another. They carried three or even four masts with lateen sails. The ships sailed into the wind well, were fast, and had a shallow draft that made them suitable for coastal as well as ocean travel. Caravels averaged a manageable 23 m (75 ft) in length and could be rowed if necessary. During the 15th and 16th centuries, hundreds of caravels sailed along the west coast of Africa and to the Americas. In the early to mid-15th century, Prince Henry the Navigator of Portugal sponsored voyages along the African coast that relied upon caravels. Famous explorer Christopher Columbus sailed caravels on his voyages of exploration under the flag of Spain in 1492. He rerigged the Niña, his favorite, with square sails on his voyage west to better use the following winds. Portuguese explorer Bartolomeu Dias sailed caravels on his voyage around the Cape of Good Hope at the southern tip of Africa in 1488. Vasco da Gama also used them to sail across the Indian Ocean to establish Portuguese colonies in Asia in 1498. By the end of the 16th century, the caravel's popularity had declined significantly. As European nations stepped up efforts to transport goods pillaged from faraway lands, demand for larger, more heavily armed ships increased. Efforts to enlarge the caravel proved unsuccessful--longer and wider versions did not sail as well as their smaller counterparts. I Galleon The 15th-century exploits of the great explorers earned riches and power for the seafaring nations of Europe. Spain devoted much of its new wealth to building a corps of battleships to accompany and protect merchant ships, laden with treasures collected in the Americas, against piracy. Toward this end, Spanish shipwrights developed the galleon, a modified, enlarged version of the carrack that became the premier ocean-going ship of the 16th and 17th centuries. Although developed as a warship, the galleon proved to be a fast and able sailer with a large cargo capacity. Most European nations adopted them to carry the treasures of Asia and the Americas back to Europe. In galleons, the hull is longer and slimmer than in carracks. A high sterncastle and long beak at the bow give the hull a crescent shape. Excellent sailers, galleons carried three masts and flew square sails on the fore and main masts and a lateen sail on the mizzen. Some galleons had a fourth mast, which carried a lateen sail called a second, or bonaventure mizzen. The typical galleon was heavily armed, having two decks with cannons and several smaller decks that served as fighting platforms. These included a half-deck, a smaller quarterdeck, and a poop deck (a partial deck aft of the main mast). Galleons fulfilled many famous missions. They were the principal fighting ships of the Spanish Armada of 1588. The small merchant galleon Mayflower brought the Pilgrims to America in 1620. The beautiful Swedish galleon Vasa, built by Dutch shipwrights for the King of Sweden, sank tragically on its maiden voyage in Stockholm harbor in 1628. A wind blew Vasa onto its side, allowing water to pour through the open gun ports. The ship lay in the mud at the bottom of the harbor until the 1960s, when it was resurrected and meticulously restored. Today the Vasa is the only surviving galleon and Stockholm's most popular public exhibit. J East Indiamen In the 17th and 18th centuries the East India companies of western Europe devoted themselves to exploiting the wealth of South and Southeast Asia. Their home governments granted them the exclusive rights to import goods, such as spices, silks, precious stones, and arts and crafts, from India, Japan, China, Indonesia, and the Malay Peninsula. The most successful of these companies reaped immense profits, year after year, for more than two centuries. East India companies carried riches between Asia and western Europe in ships called East Indiamen. These huge, three-masted merchant ships measured 800 tons or more and were armed with cannons on two gun decks to protect their valuable cargoes from piracy. In many cases, East Indiamen served as monuments to the power and riches of the companies that owned them and the countries from which they hailed. The massive ships were decorated with ornate, gilded carvings, and the interiors boasted luxurious wood and fabric finishes. K Ships of the Line Sail-powered naval warfare climaxed from 1650 to 1840. During this period, ships carried heavy artillery to destroy their opponents--as many as 100 cannons, most placed in gun ports on the sides of the vessel. To accommodate the cannons, which could fire only straight out to the side of the vessel, warships fell into position in long orderly lines. The enemy usually lined up in the same formation and battle commenced, broadside against broadside. This battle configuration earned the warships powerful enough to fight on the front lines of battle the name ships of the line. From the 17th century, British warships were rated in six classes, according to the number of guns they carried. Ships of the line claimed the highest ratings. First-rate ships had three gun decks with over 100 guns. Third-rate battleships with 60 guns or more were typically the lowest-rated vessels used as ships of the line by the British navy. In rare cases, fourth-rate ships, which had between 40 and 60 guns, served as ships of the line. Other navies used similar rating systems. Ships of the line increased in size and firepower during the years that they were popular. In the mid-17th century the largest ships of the line reached 1,500 tons. By 1750 ships of 2,000 tons or more were common, and by 1800 ships of the line usually exceeded 2,500 tons. The hulls of these massive warships were often reinforced with double-layered oak planks up to 46 cm (18 in) thick. Such construction required unprecedented amounts of wood. For example, about 2,500 mature oak trees were used to build HMS Victory, Britain's flagship at the famous Battle of Trafalgar in 1805. This superlative ship featured 32 km (20 mi) of rope and had a crew of 850 sailors and marines. Like the East Indiamen merchant ships, ships of the line often served as monuments to the powers that built them. In many cases, no cost was spared in their construction. They were highly decorated with woodcarvings and featured officers' quarters designed for comfort and elegance. Such luxuries were not extended to all the sailors, however. Most of the crew slept in hammocks suspended from beams on the gun decks. L Frigates, Sloops, and Brigs In the 17th and 18th centuries, naval powers rated their battleships according to firepower. Fifth-rate and sixth-rate ships had fewer than 40 guns and were not considered powerful enough to fight in the front lines of battle. Classed as frigates, these ships were used to support ships of the line. They performed reconnaissance work, protected their own country's merchant ships, and attacked the merchant ships of enemy nations. Early frigates were light and fast. They carried three masts and could maneuver well in the close quarters of battle. Galley frigates were outfitted with oars as well as sails, making them even more agile in battle. They also cost less to build and maintain than their giant, heavily armed counterparts. These strengths appealed to the Congress of the United States, which created the United States Navy in 1794 and authorized the construction of six frigates. The United States, the Constitution and the President were armed with 44 guns, while the Constellation, the Chesapeake, and the Congress each had 36 guns, but two were soon upgraded to 38 guns. The Constitution, launched in 1797, earned the nickname Old Ironsides in 1812 for repelling the cannon balls fired by the British frigate Guerrière. Today berthed in Boston, Massachusetts, the Constitution is the oldest ship in the U.S. Navy and the oldest warship afloat. Several types of smaller battleships also commonly operated in naval warfare in the 17th, 18th, and 19th centuries. The sloop (or corvette, the French equivalent) ranked below the frigate in firepower. Sloops had two masts, carried about 100 men, and were armed with 18 or fewer guns. Sloops ran down privateers, privately owned, armed vessels that preyed on merchant ships. The brig also saw military action. Two-masted with several square sails, brigs served in many European navies of the 18th century. In the United States the brig Niagara became famous for its part in the defeat of the British at the Battle of Lake Erie in 1813. M Clippers In the middle of the 18th century, speed surpassed cargo capacity as the most important feature for merchant ships. Speed was especially valued by traders engaged in the lucrative Atlantic slave trade and the Chinese opium and tea trades. Traders had to outrun pirates and warships, so speed won shipping contracts at higher rates per ton of cargo carried. These conditions necessitated the development of clippers, fast sailing ships probably named for the time they clipped from standard passages between ports. The term clipper ship is sometimes used as a synonym for any fast ship, but true clipper ships have distinct features designed for speed. True clippers began to appear in the late 1840s. A clipper has a long, sleek hull with a sharp bow and an overhanging stern to reduce contact with the water, thereby reducing drag. It typically has three tall masts that fly as many as five sails each. Later clippers, such as the Cutty Sark in Greenwich, England, were built with iron frames covered with wood planks. The clippers revolutionized long-distance shipping. The 1,700-ton Flying Cloud made the 29,000-km (18,000-mi) passage from New York City, New York, to San Francisco, California, in only 89 days. The American clipper Oriental sailed from New York City to Hong Kong in a record 81 days. From 1849 the Chinese tea trade attracted clippers, as did the California gold rush. Prospectors wanted to travel from the East coast to California as quickly as possible. To this day, clippers are revered as some of the most beautiful ships in history. N Last Days of Sail Sailing ships of the later 19th century underwent dramatic changes. Hulls were built of iron and later, steel. Steel also replaced wood in masts, and shipbuilders turned to wire and chain instead of rope made from hemp. The new materials enabled the construction of huge sailing ships, such as the German-built Preussen (1902), a fivemasted steel ship over 120 m (400 ft) long. Preussen carried 47 sails that had a total area of 4,650 square meters (5,560 square yards). Some of these vessels carried auxiliary steam engines with propellers. The largest merchant sailing vessel ever built, the 128-m (419-ft) France II, carried two steam engines. The efficiency and growing reliability of steam-powered vessels hastened the end of the age of sail. Steamships edged out sailing ships in the Chinese tea trade following the opening of the Suez Canal in 1869, and in the South American nitrate trade when the Panama Canal opened in 1914. The use of U-boats in World War I (19141918) to attack merchant ships created a need for military escorts, but sailing ships were vulnerable and not well suited to sail in closely formed convoys. One of the last remaining uses for sailing ships was transoceanic mail delivery. Called packet boats after the British nickname for the mail dispatch, mail ships were built for speed. They carried mail to overseas locations, usually under the control of the home country. Britain ran post office packet ships on regular runs in the early 19th century. But by the mid-19th century, the British were contracting with private firms, such as the Cunard Line and the Peninsular and Oriental Steam Navigation Company, to deliver mail in steamships. The surviving great sailing ships found roles as training ships for navies, and several still serve in this capacity today. They can often be seen together at maritime festivals and other gatherings of tall ships. Today the legacy of the great sailing ships lives on in the competitive and leisure-time activity of modern sailing. IV FUEL-POWERED SHIPS The first fuel-powered ships were centuries in the making. French physicist Denis Papin envisioned a steamship as early as 1685, but nearly 100 years passed before Marquis Claude de Joffroy d'Abbans built and operated a steamship. In 1783 his vessel, Pyroscaphe, steamed up the Saône River in France for nearly 15 minutes. Three years later American John Fitch powered a vessel on the Delaware River with a steam engine that moved vertical oars. Fitch went on to found a passenger and freight service between New Jersey and Philadelphia, Pennsylvania, but the venture failed. Early steamships were unreliable and posed little competition to the graceful, highly advanced sailing vessels of the day. Until well into the 20th century, sailing vessels and steamships coexisted. Gradually, fuel-powered ships grew faster and their schedules became more predictable than those of sailing vessels. A Paddlewheel Steamships The first practical steam-powered vessel was the Charlotte Dundas, a 15-m (50-ft) paddlewheel steamboat that towed two 70-ton barges almost 32 km (20 mi) on the Forth and Clyde Canal in Scotland in 1802. American inventor Robert Fulton sailed aboard the Charlotte Dundas and immediately sensed that there was rich potential for steam in America. After trials with his ship Steam Boat, Fulton designed and assembled the first successful commercial steamboat, Clermont, in 1807. Clermont measured 41 m (133 ft) long and was powered by a steam engine built by Scottish inventor James Watt. Watt's engine drove two paddlewheels mounted on the sides of the ship. Clermont steamed up New York's East Hudson River from New York City to Albany and back, covering a total distance of 385 km (240 mi) in 62 hours. Fulton's enthusiasm for steamships proved infectious, and soon paddlewheel steamships carried passengers and freight on canals and rivers and on coastal runs across both the eastern United States and western Europe. In 1818 the American steamship Savannah became the first steam-powered vessel to cross the Atlantic Ocean. Throughout much of this groundbreaking trip, however, the ship operated under sail power. Early steamships relied heavily on sail power because their engines required more coal than could reasonably fit aboard the ship. Moreover, sail power provided a necessary alternative to the notoriously unreliable steam engines of the time. Ships rapidly grew larger, more efficient, and more comfortable, making transoceanic steamship travel more palatable. In 1838 the Great Western became the first steamship to offer regular passage across the Atlantic Ocean. Built and designed by pioneering British ship designer Isambard Kingdom Brunel, Great Western measured 72 m (236 ft) long and traveled between Bristol, England, and New York City in just 15 days. Great Western's comfort and reliability initiated a new era in transportation. The same year, the British government solicited bids to build a fleet of paddlewheel steamships to deliver mail between the United States and England. The paddlewheel steamers were to replace Britain's famous line of packet sailing ships. British ship owner Samuel Cunard won the contract, and in 1840 he established the Cunard Line to provide transatlantic mail service between Liverpool, England, and Boston, Massachusetts, twice a month. Business boomed, and Cunard soon expanded its operations to include passenger service between the two countries. In spite of their success, paddlewheel steamers posed many problems to their passengers and crew. For example, they lacked stability in the water. When a steamship listed slightly to the side, one paddlewheel lifted out of the water, while the other submerged entirely under the water. This made for an uncomfortable ride and placed great strain on the engine. Paddlewheel steamers also proved impractical as battleships. The large paddlewheels left little space to mount guns, and the engines and coalbunkers filled what little space remained for the crew. B Innovative Ships of the Late 19th Century The second half of the 19th century proved a prolific period for marine steam propulsion. Shipbuilders introduced innovative solutions to earlier problems with each new ship they built. They eliminated the need for paddlewheels, turned to iron and later steel for hull construction, and significantly improved the steam engine. B1 The Screw Propeller A major development in ship propulsion was the screw propeller, fully submerged rotating blades that pushed the ship through the water. The screw propeller was first used in 1840 on the Archimedes, a river-going American steamer. British shipbuilder Brunel again pioneered ship design when he adopted the propulsion system of the Archimedes for his second ship, Great Britain, in 1853. At 98 m (322 ft), Great Britain was the largest steamship of its day, the first to be made of iron, and the first seagoing ship driven by a screw propeller. Great Britain's propeller measured nearly 5 m (16 ft) in diameter and weighed more than 3 tons. The earliest screw propellers used on ships had two long, narrow blades, resembling the propellers of early aircraft. Soon propellers with three, four, and even more blades were in use, and ships carried two, three, or more propellers. Multiple propellers increased speed and provided alternatives in the event that one propeller malfunctioned or was lost. B2 Iron and Steel Hulls Brunel combined elements from the Great Western and the Great Britain in his third and final ship, the Great Eastern, which launched in 1858. Iron-hulled and propelled by a combination of paddlewheels and screw propellers, Great Eastern dwarfed even the largest ships of the day. Before Great Eastern, the longest ship afloat measured 114 m (375 ft) and 3,300 tons. Great Eastern stretched 211 m (692 ft) in length and measured 19,000 tons. Despite its gargantuan proportions, the ship failed as a passenger liner. It went on to lay the first transatlantic electric telegraph cable. Nonetheless, the Great Eastern proved a trendsetter. Following Brunel's lead, most shipbuilders constructed ships from large iron plates riveted together. Iron ships had stiffer hulls, which helped to reduce vibration from the movement of the long propeller shaft. But iron presented a new set of challenges to builders. Iron was rigid, it fractured easily, and it rusted. Shipbuilders found an alternative in steel, a mixture of iron and other elements, which is stronger and easier to shape than iron. Steel's exorbitant cost and relative scarcity made it an impractical choice until 1855, when English inventor Henry Bessemer improved the steel refining process. The Bessemer process made good quality steel available at a fraction of its earlier price. By the end of the 19th century, most of the great merchant and battleships featured steel hulls. B3 Double- and Triple-Expansion Steam Engines Steam engines also improved significantly. In early steam engines, steam from the boiler was directed to a cylinder, where it drove the movement of a single piston before it was expelled. These single-expansion engines wasted some of the steam's energy. More efficient double-expansion engines used the steam expelled from one cylinder to power another cylinder. By 1873 even more efficient triple-expansion engines came into use. B4 Steam Turbines Further experimentation with steam engines led to the development of steam turbines, which used steam from the boilers to turn fan blades at high speed. This mechanical energy was harnessed to turn the propeller shaft. In 1897 British engineer and visionary Charles Parsons captured the attention of the British navy and royal family with his ship, Turbinia, the world's first steam turbine-driven vessel. Parsons piloted Turbinia through a parade of British naval ships at an astounding 34.5 knots (63 km/h; 39 mph), shocking all in attendance. The Royal Navy's fastest ships gave chase but could not catch up to the speeding Turbinia. Two years later Britain launched the first steam turbine-driven warship, HMS Viper, which made 36.5 knots. B5 Diesel Engines Despite its bulk, coal remained the fuel of choice until the beginning of the 20th century. In 1897, the same year that Parsons demonstrated the steam turbine before the British navy and royal family, German engineer Rudolf Christian Karl Diesel built an engine that ran on petroleum-based liquid fuel. Although early diesel engines could not match the speed of coal-fired steam engines, they were lighter and did not require boilers, water, and bulky coal to generate steam. Diesel engines could be operated by fewer crewmembers and did not require a team of firemen to shovel coal. By the early 1900s diesel engines began to replace coal-fired engines. Diesel engines powered barges hauling crude oil up rivers from the Caspian Sea to northern Europe. The first sea-going vessel fitted with a diesel engine was Vulcanus, a small merchant vessel built for the Dutch East India Company in 1910. Despite their advantages over steam engines and turbines, diesel engines were slow to replace steam power in passenger liners, which highly valued speed. C The Great Ocean Liners Toward the end of the 19th century the enormous flow of emigration from Europe to the United States made transatlantic passenger service a booming business. Companies competed with each other to attract first- and second-class passengers, whose high fares provided the bulk of an ocean liner's operating costs. They built ships with lavish passenger accommodations and opulent decor. The 128-m (420-ft) Oceanic, built in 1871 for the White Star Line passenger service company, set the standard for all ocean liners. Oceanic was steel-hulled, propeller-driven with auxiliary sails, and had a passenger deck with cabins lining the ship's sides, rather than tucked below decks or in windowless, inner compartments. In addition to lavish passenger accommodations, companies also sought ways to decrease the crossing time between Europe and the United States. The Cunard Line was the first to fit an ocean liner with steam turbines. Cunard commissioned two of the greatest liners ever built, the Mauretania and the Lusitania, which both launched in 1906. Each 240-m (790-ft), 28,000-ton vessel was powered by four coal-fired steam turbines that drove four propellers. These engines moved the sister ships through the water at an impressive 27 knots. The White Star Line upstaged the other lines when it ordered two new ships for the Atlantic passage--the Olympic and the Titanic. At 260 m (852 ft) and 46,000 tons, these were the greatest ships afloat. Watertight bulkheads divided their hulls into 16 compartments, a design that was said to make the ships "unsinkable." However, Titanic sank on its maiden voyage when it struck an iceberg on April 14, 1912, off Newfoundland (Titanic Disaster). A severe shortage of lifeboats contributed to the deaths of more than 1,500 people. The Titanic was not the only ocean liner to meet a tragic end. The Lusitania's service ended when the ship was struck by a torpedo from a German U-boat in 1915. World War I (1914-1918) and World War II (1939-1945) claimed many of the great ocean liners. Great Britain requisitioned Cunard's prize liner Mauretania in 1914 to transport troops between England and the Mediterranean. Cunard's Queen Mary, 310 m (1,018 ft) long and capable of over 30 knots, and its sister ship Queen Elizabeth were both stripped down, painted gray, and used as troop transports in World War II. The elegant French ocean liner Normandie met a similar fate. The stateof-the-art ship measured 314 m (1,029 ft), made 30 knots, and showcased some of the most celebrated art nouveau décor in the world. The Normandie was laid up in New York when World War II erupted in Europe in 1939. The United States government requisitioned the luxury liner to serve as a troop ship. The Normandie caught fire while being converted to a utilitarian troop transport, and the ship capsized from the water pumped onto it by firefighters. The luxury liner industry never recovered after the war. Although many more liners were built, labor problems and rising fuel costs limited their profits. The final blow to the once-thriving transatlantic passenger liner industry came with the widespread use of jet airplanes, which revolutionized the air transport industry and cut deeply into passenger liner profits. By 1958 more people crossed the Atlantic by air than by sea, and most of the once-mighty liners had fallen into disrepair or found other roles. The Queen Mary is now a hotel and conference center in Long Beach, California. The Queen Elizabeth was moved to Hong Kong and converted into a floating university. In 1972 the ship caught fire and sank to the bottom of Hong Kong Harbor. The only passenger liners that still cross the Atlantic Ocean are the Queen Elizabeth 2 (QE2) and the Queen Mary 2 (QM2). The QE2 was launched by Cunard Lines in 1967 as an heir and tribute to the great ocean liners of the first half of the 20th century. The QE2 measures 294 m (963 ft) long and travels at about 30 knots. The QE2 makes transatlantic crossings between Southampton, England, and New York City in the summer months and serves as a cruise ship during the winter. The maiden voyage of the QM2, the world's largest passenger liner, occurred in January 2004. The QM2 is 345 m (1,132 ft) long and 72 m (236 ft) high, rising 23 stories above the water, and can carry about 2,600 passengers. It operates between Southampton and Fort Lauderdale, Florida, and also spends time as a cruise ship in the Caribbean, South America, and along the East Coast between New York City and Newport, Rhode Island. The QM2 is operated by Cunard Lines, which was acquired by the U.S.based Carnival Corporation in 1998. D Cruise Ships Following the demise of the great ocean liners, cruise ships emerged as the lavish and opulent ships of the sea. Although cruise vacations date from the 19th century, they did not reach the popularity they enjoy today until the 1960s. Cruise ships of the 1960s and 1970s typically measured 180 m (600 ft) or less and carried 600 to 700 passengers. The elegant vessels, featuring swimming pools, theaters, restaurants, and luxurious passenger accommodations, expanded the cruise vacation industry significantly. As demand for new cruise ships grew, companies built larger, more elaborate ships. The Royal Princess, built in 1984 and operated by cruise company Princess Cruises, is twice the size of its 1970s predecessors and carries 1,250 passengers. The Jubilee and Celebration, both operated by Carnival Cruise Lines, measure nearly 230 m (750 ft) and carry 1,850 passengers. The boom continued into the 1990s and the early 21st century with the building of floating entertainment centers on a scale never before imagined. The Royal Caribbean Cruises ship Voyager of the Seas, for example, carries nearly 5,000 passengers and crew in her 310-m (1,020-ft) hull. The ship cost $500 million to build and outfit and features a floating casino, a luxurious 1,350-seat theater, a 9-hole miniature golf course, an ice rink, and a shopping mall. From 2000 to 2004, U.S. cruise lines launched 50 new cruise ships, including the Queen Mary 2, the largest passenger ship yet built in length, width, and height. At a cost of $800 million, the QM2 features four outdoor pools and one indoor pool, a six-story-high atrium, and a 1,900-sq-m (20,000-sq-ft) spa. E Cargo Ships Cargo ships carry manufactured goods, foods, coffee, textiles, metals, minerals, and edible oils across the world's oceans or other large bodies of water. Modern cargo ships usually feature derricks (onboard loading cranes) to expedite loading and unloading. They have refrigerated containers for carrying meat, fish, fruit, and bulk liquids such as orange juice. Cargo ships may be designed to carry a single product, such as sea-going ore carriers, or they may have a general design that enables them to carry a variety of cargoes. Cargo ships may follow regular shipping routes, or they may travel from port to port carrying any available cargoes. Cargo ships that follow established routes are called liners. They run along fixed routes and charge standard rates. Cargo vessels that move from port to port without following a fixed route are called tramps. Tramps carry whatever loads are available. The work of a tramp is facilitated by brokers at the maritime centers at London, England; New York; and Tokyo, Japan. These brokers match available ships with shippers and negotiate prices. E1 Container Ships When the costs of shipping escalated rapidly in the 1950s, studies showed that labor constituted over 50 percent of the rising costs. Dockworkers spent five days or more unloading a large cargo ship and the same amount of time reloading it. Moreover, shipping companies paid port authorities large fees for each day they spent docked in port. American trucker Malcolm McLean offered a solution to this problem in the 1950s when he introduced the concept of containerized shipping. McLean proposed the use of standardized shipping containers to integrate truck, train, and ship transport. In 1956 Sea-Land Service commenced containerized shipping operations between New York City and Houston, Texas. The shipment of cargo in prefabricated steel containers with standard measurements reduced labor costs and port fees significantly. The use of containerized shipping rapidly expanded, and today, ships, trains, and trucks are loaded and unloaded using huge mechanical cranes that unload and load a ship in just 24 hours. E2 Roll-On-Roll-Off and LASH Vessels Alternatives to the container system include roll-on-roll-off ships and LASH vessels. Roll-on-roll-off ships have stern and side openings through which dockworkers drive wheeled containers, cars, trucks, house trailers, and other cargo that can be rolled aboard. LASH stands for lighter aboard ships. In the LASH, or barge carrier, system, a giant crane lifts preloaded barges, or lighters, onto the vessel's decks, eliminating the need for the ship to tie up in port at a dock. F Tankers The increasing global dependence on petroleum products--from gasoline, kerosene, and diesel to plastics and chemicals--has made petroleum tankers the largest ships afloat. The world's tanker fleet doubled in number and tripled in tonnage between 1939 and 1959. Tankers are essentially giant holding tanks, or sometimes a series of tanks, shaped like ships and powered by engines. They are equipped with sophisticated piping systems for loading and unloading their contents, fire control systems, navigation equipment, control rooms, and crew quarters. F1 Crude Carriers Crude carriers transport crude oil from oil wells in the Persian Gulf, Alaskan waters, the North Sea, and other oilfields to oil refineries, where it is converted into useful petroleum products. The largest tankers afloat are called ultra large crude carriers (ULCCs). These enormous ships hold more than 300,000 tons and extend well over 300 m (1,000 ft) in length. ULCCs are so large they cannot pass through the Suez and Panama canals, nor can they enter most harbors. Instead, most ULCCs unload into smaller tankers at offshore pumping stations. Comparing the size of a ULCC with the Titanic illustrates the size of these giant ships. The Titanic measured just over 268 m (880 ft) in length and 46,328 tons. The Batillus, a ULCC built in 1976, stretches 414 m (1,358 ft) and holds 275,267 tons, five times more than the Titanic. F2 Product Tankers Product tankers carry refined petroleum products from oil refineries to ports around the world, where the products are transferred to trucks and rail cars to be distributed to consumers. Product tankers are much smaller than the crude carriers; the most recent are only around 20,000 tons and just short of 180 m (600 ft) long. Besides being smaller than crude carriers, products tankers are more complex. Instead of consisting of a single giant tank, they feature multiple tanks that can carry a variety of refined products. F3 Other Specialized Tankers Other specialized tankers include chemical tankers, liquefied gas carriers, and ore/bulk/oil carriers. Chemical tankers carry various chemicals from port to port. Liquefied gas carriers transport natural gas and petroleum gas. These products are carried in a liquefied form rather than as gases because liquids take up less space than the same amount of gas. To maintain their cargo in liquid form, liquefied gas carriers hold cargo under pressure and at very low temperatures to prevent it from vaporizing. They are constructed of special types of steel that can withstand the stresses of pressure and cold. Ore/bulk/oil carriers, or OBOs, are versatile ships that can perform as tankers but carry several cargoes at once. The first OBO was put in service in 1985. Most are of panamax size, meaning that they are not too large to pass through the Panama Canal. F4 Tanker Safety Tankers of all kinds carry potentially dangerous cargo, and a few have caused environmental disasters of tragic proportions. The 1967 wreck of the oil tanker Torrey Canyon devastated the marine environment off the coast of Great Britain. In 1989 the American oil tanker Exxon Valdez ran aground in Prince William Sound, Alaska, eventually coating 1,770 km (1,100 mi) of the Alaskan coastline with deadly crude oil. These and other devastating oil spills have led to international discussions about whether to institute regulations requiring that oil tankers have double hulls. In particularly sensitive areas, regional governments may require that small local pilot boats captained by sailors familiar with underwater topography accompany tankers when they reach coastal waters. G Fishing Vessels Modern fishing vessels range from one-person wooden rowboats equipped with hand or casting nets to large, steel-hulled ships that range far from their home ports and track their prey using the latest modern technology. Three main types of fishing ships over 40 m (130 ft) in length currently ply the world's oceans: trawlers, seiners, and long liners. G1 Trawlers Trawlers catch fish by dragging large nets over the seafloor or through the water, then hauling the nets aboard with motorized winches. The earliest trawlers were sailpowered. Diesel engines power modern trawlers, the largest of which reach 120 m (400 ft) in length. They are usually equipped with facilities for freezing their catch to keep it fresh until they reach shore. Large trawlers can store 8,400 cubic meters (296,600 cubic feet) of frozen fish. Trawlers hunt salmon, shrimp, haddock, and many other types of edible sea-dwelling organisms. G2 Seiners Seiners, like trawlers, catch fish in nets. But on seiners, the mouth of the net is drawn closed before it is hauled aboard. Seine fishing originated in Denmark in the middle of the 19th century and descended from casting nets from shore. Modern seiners normally operate throughout the North Atlantic Ocean, pursuing tuna and other fast-swimming species. They can also be found ranging across the warmer waters of the Pacific in search of tuna or off the coast of South America working the much depleted anchovy stocks (see Fisheries). G3 Long Liners Long liners deploy long fishing lines with hundreds or even thousands of baited fishhooks spaced at intervals. The line is towed for a time and then hauled aboard so fishers can remove fish that have taken the hooks. Long liners tend to be smaller than fishing vessels that use nets--the largest fish for tuna in the Pacific Ocean and measure slightly over 60 m (200 ft) in length. These ships use fishing lines that extend over 100 km (60 mi) behind the ship. Other long liners fish for various species of cod in the North Atlantic. H Research Vessels Scientific research ships date from the 1870s, when the United States, Britain, and Germany launched expeditions to conduct oceanic research. The most significant of these was the HMS Challenger expedition led by Sir Charles W. Thomson from 1872 to 1876. Scientists aboard the 60-m (200-ft) sailing vessel spent four years studying the ocean terrain and collecting information on thousands of marine species. The Challenger expedition marked the beginning of the fields of oceanography and deep-sea exploration. A host of vessels have engaged in scientific research since the Challenger's day. These vessels conduct research related to oceanography, geology, meteorology, and marine geography. Some scientific research vessels were specially designed and constructed for that purpose, while others have been converted to research vessels after another career. These floating laboratories feature high-tech computers, sonar, and sampling equipment used to study the ocean and its inhabitants. They are usually manned by a professional crew and a separate cadre of scientists. They range in size from relatively small sailing vessels in the tradition of the Challenger to modern craft as large as 90 m (300 ft) in length. Research vessels are financed and operated by national governments, educational institutions, private research organizations, or partnerships between these organizations. In the 1960s Global Marine Development, a privately owned company, financed the construction and operation of the 120-m (400-ft) Glomar Challenger, named for the famous 19th century British ocean research vessel. Glomar Challenger was the first research vessel built to drill core samples from the deep ocean seabed. Research scientists aboard the ship found evidence that strongly supports the theory of plate tectonics, which holds that Earth's continents were once joined together and have gradually separated. The equally well-known research vessel Glomar Explorer was built in 1973, ostensibly to explore the possibility of deep-sea mining for Global Marine Development. Years later, the Central Intelligence Agency revealed that they used the Glomar Explorer to explore and raise a Soviet ballistic submarine that sank in 4,000 m (13,100 ft) of water in the Pacific Ocean. They also revealed that Global Marine's involvement was meant only to serve as a cover for the top-secret operation. Once the covert operation had been completed, the Glomar Explorer spent two years exploring the feasibility of mining manganese from the ocean bottom. I Hovercraft Hovercraft, also called air-cushion vehicles, travel over the surface of, rather than through, the water. They use large lift fans to push down air, which is trapped inside a heavy rubber skirt. The skirt gives the craft the hover height necessary to clear waves and other obstacles. Without water resistance, these ships can travel at up to 65 knots over the water. If their skirts or lift fans fail, the hovercraft settles onto the surface of the water and floats for the rest of the trip to port. The first commercial hovercraft entered service in 1968 as a passenger transport across the English Channel. Most hovercraft in use today operate as high-speed passenger and automobile ferries. The largest of these craft measure 39 m (128 ft) or more and carry up to 610 passengers. The United States military commissioned hovercraft for use in amphibious warfare. Military hovercraft can transport troops across the water and the beach safely and more efficiently than other amphibious vehicles. J The First Nuclear-Powered Vessels The most revolutionary development in ship propulsion was nuclear power, first used in the submarine USS Nautilus in 1954. Nautilus cruised at more than 20 knots and could remain submerged for almost unlimited periods. In 1958 the Nautilus made the first undersea crossing at the North Pole. The Nautilus could fire guided missiles or ballistic missiles at enemy land targets from a submerged position. Nautilus's successes were legendary, and soon all the major naval powers had nuclear submarines in their fleets. In 1962 the first commercial nuclear-powered ship, the NS Savannah, was launched in Camden, New Jersey. Named for the Savannah, the famous 19th-century steamship that pioneered transatlantic steam travel, NS Savannah measures 182 m (596 ft) and is powered by nuclear-driven turbines. Although it was an engineering success, NS Savannah proved a commercial failure. It could not carry enough cargo to be competitive and required a larger crew than comparable oil-powered ships. NS Savannah remains the only commercial nuclear-powered vessel ever built. Nuclear power proved prohibitively expensive for commercial purposes. The military recognized the potential for nuclear power. Unrestricted by cost, navies of the United States, Russia, Britain, and France developed a variety of naval vessels operated by nuclear power. K Naval Vessels Like their sailing predecessors, power-driven naval vessels are designed for various operations involved in modern naval warfare. Contemporary naval fleets include aircraft carriers, cruisers, destroyers, frigates, mine craft, and a variety of transport and support vessels. Naval vessels generally have a slender hull shape that gives them greater speed than their merchant counterparts, which cannot economically sacrifice cargo-carrying capacity for speed. K1 Aircraft Carriers The most important naval ships of modern times, aircraft carriers are massive vessels equipped with flight decks to support the takeoff and landing of military aircraft. The largest and most advanced carriers in the world belong to the Nimitz class. Nimitz carriers stretch 333 m (1,092 ft) in length and carry 85 aircraft. Their crews number more than 3,000, and they also house aircrew and support teams numbering almost 2,500. They are powered by a two-reactor power plant. K2 Battleships The modern battleship traces its ancestry to the first-rate ships-of-the-line of the sailing era. Until recently, modern battleships served on the front lines of sea battles throughout the world. They have largely been replaced by aircraft carriers. The last battleships built in the United States were of the Iowa class. The four Iowa-class vessels entered service in the 1940s. The U.S. Navy modernized them in the 1980s, then removed them from service in the 1990s. These steel-hulled ships measured 270 m (885 ft) and traveled at an unprecedented speed of 33 knots. K3 Cruisers Modern cruisers measure from 162 to 243 m (533 to 796 ft) in length, travel about 30 knots, and have an average crew of 550. The mission of modern cruisers is to destroy enemy surface ships, submarines, aircraft, and missiles. They are equipped with 5-inch guns, Harpoon and Tomahawk guided missiles, antisubmarine warfare helicopters, and torpedoes. Many cruisers now have the Aegis surface-to-air missile system, a highly sophisticated and capable weapons system. K4 Destroyers The modern destroyer is a light, fast, ship that serves a great variety of functions because of its speed, armament, and maneuverability. It replaced the navy war sloop of the sailing era. Destroyers provide antiair, antisurface, and antisubmarine warfare capabilities. They carry 5-inch guns, a variety of antiship missiles, antisubmarine helicopters, and torpedoes. They range from 133 to 172 m (437 to 563 ft) in length, travel at speeds ranging from 30 to 33 knots, and have crews of about 400. K5 Frigates Like its sailing predecessor, the modern naval frigate serves as an ocean escort. It ranges from 126 to 136 m (414 to 445 ft) in length and cruises at below 30 knots. Modern frigates require crews of between 200 and 300 sailors. Most are lighter armed than destroyers, although some frigates carry missiles, antisubmarine rockets, and helicopters, torpedoes, or other weapon systems. K6 Mine Craft Mine craft include minesweepers and mine countermeasure ships. Minesweepers detect and clear, or sweep, explosive underwater mines so that ships can pass safely. They measure 57 m (188 ft) long and carry a crew of 45. Mine countermeasure ships detect and sweep underwater mines and serve as command and control facilities for mine countermeasure operations. Mine countermeasure ships measure 68 m (223 ft) in length and have a crew of 74. V NEW TRENDS IN SHIP DESIGN Although the ship remains the most economical way to transport bulk cargoes over the world's oceans, naval architects recognize that room for improvement remains. Most of today's cargo vessels travel at a speed of about 20 to 23 knots, limited by their hull design. Naval architects are exploring the use of multiple hulls--instead of having one large hull, ships might have two or three hulls connected to each other. These designs are prominent in small- to medium-sized boats but have not been applied to bulk carriers. The catamaran (two hull) or trimaran (three hull) offers great stability with much less water resistance. Concerns about applying such designs to bulk cargo carriers persist, however. Some question the potential strength of large, multiple-hulled ships in rough seas. Others argue that multiple-hulled cargo carriers would not have adequate carrying capacities to make them economical. Naval architects are also exploring the use of narrower hulls in single-hulled cargo vessels. Military vessels throughout history have used slender hulls, which enable ships to travel faster because they experience less drag in the water. Many question the potential stability of the slender-hulled cargo ship, which will undoubtedly make transoceanic crossings with containers stacked high on its decks. Moreover, a narrow-hulled ship cannot carry as much cargo as a modern freighter of equivalent length. The solution may lie in the semiplaning monohull. This hull design has a sharp V-shaped bow for cutting the waves and a wide, shallow rear with a slightly concave profile underwater. This design creates waves that help lift the vessel and reduce drag in the water. These hulls, similar to those used in many modern pleasure boats, would become more efficient as the ship goes faster. New designs in ship propulsion will also increase the efficiency of ship transport. When compared to marine diesel engines of the same weight and volume, gas turbine engines produce far greater amounts of power without using more fuel. They also burn cleaner, emitting only 4 percent of the sulfur oxides and 5 percent of the nitrogen oxides emitted by diesels of the same power. Gas turbine engines currently power small passenger and car ferries, but they have been prohibitively expensive for use in bulk cargo transport. In the future, water jet drive may replace the screw propeller. Both of these propulsion systems spin and push water to move the vessel. But while the screw propeller becomes less efficient at high speeds, the water jet drive gains efficiency as speed increases. Such changes will undoubtedly make the ships of tomorrow faster and more efficient. Naval architects and engineers predict that a ship with a semiplaning monohull, gas turbine engine, and water jet drive will easily reach a speed of 45 knots. These and other innovative ship designs will cut the cargo crossing time between Europe and North America from 14 to 35 days to a week or less. Contributed By: Timothy J. Runyan Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.