Ship
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226136504
2008-07-16T23:55:08Z
24.60.209.129
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[[Image:Amerigo vespucci 1976 nyc aufgetakelt.jpg|thumb|333px|[[Italy|Italian]] [[Full rigged ship]] [[Amerigo Vespucci (ship)|''Amerigo Vespucci'']] in [[New York Harbor]], 1976]]
A '''ship''' {{IPA|/ʃɪp/}} {{audio|en-us-ship.ogg|Audio (US)}} is a large [[watercraft|vessel]] that floats on water. Ships are generally distinguished from [[boats]] based on size. Ships may be found on [[lake]]s, [[sea]]s, and [[river]]s and they allow for a variety of activities, such as the [[ferry|transport of persons]] or [[cargo ship|good]]s, [[fishing]], [[cruise ship|entertainment]], [[Coast guard|public safety]], and [[warship|warfare]].
Ships and boats have developed alongside mankind. In major wars, and in day to day life, they have become an integral part of modern commercial and military systems. Fishing boats are used by millions of fishermen throughout the world. Military forces operate highly sophisticated vessels to transport and support forces ashore. Commercial vessels, nearly 35,000 in number, carried 7.4 billion tons of cargo in 2007.<ref name="unctad07x">UNCTAD 2007, p. ''x'' and p. 32.</ref>
These vessels were also key in history's great explorations and scientific and technological development. Navigators such as [[Zheng He]] spread such inventions as the [[compass]] and [[gunpowder]]. On one hand, ships have been used for [[colonization]] and the [[slave trade]]. On the other, they also have served scientific, cultural, and humanitarian needs.
As [[Thor Heyerdahl]] demonstrated with his tiny boat the ''[[Kon-Tiki]]'', it is possible to achieve great things with a simple log raft. From [[Mesolithic]] [[canoe]]s to today's powerful nuclear-powered [[aircraft carrier]]s, ships tell the history of man.
== Nomenclature ==
[[Image:ship diagram-numbers.svg|thumb|right|Main parts of ship. '''1''': [[Smokestack]] or [[Funnel]]; '''2''': [[Stern]]; '''3''': [[Propeller]] and [[Rudder]]; '''4''': [[Portside]] (the right side is known as [[starboard]]); '''5''': [[Anchor]]; '''6''': [[Bulbous bow]]; '''7''': [[Bow (ship)|Bow]]; '''8''': [[Deck]]; '''9''': [[Superstructure]]|300px]]
{{detail|Glossary of nautical terms}}
There is no universal rule to distinguish a ship from a boat. Usually, ships are larger than boats. A commonly used [[rule of thumb]] is that if one vessel can carry another, the larger of the two is a ship. As [[dinghy|dinghies]] are common on [[sailing yacht]]s as small as {{convert|35|ft|m}}, this rule of thumb is not foolproof.
A number of large vessels are traditionally referred to as boats. [[Submarine]]s are a prime example. Other types of large vessels which are traditionally called boats are the [[lake freighter|Great Lakes freighter]], the [[riverboat]], and the [[ferryboat]]. Though large enough to carry their own boats and heavy cargoes, these vessels are designed for operation on inland or protected coastal waters. However referring to ships as 'boats' is more an American tradition than that followed in 'British' style Merchant Navies.
==History==
===Prehistory and antiquity===
[[Image:Floss.jpg|left|thumb|A [[raft]] is among the simplest boat designs.]]
The history of boats parallels the human adventure. The first known boats date back to the [[Neolithic Period]], about 10,000 years ago. These early vessels had limited function: they could move on water, but that was it. They were used mainly for [[hunting]] and [[fishing]]. The oldest [[dugout canoe]]s found by archaeologists were often cut from [[coniferous tree]] logs, using simple [[stone tool]]s
About 5,000 years ago, people living near [[Kongens Lyngby]] in Denmark invented the segregated hull, which allowed the size of boats to gradually be increased. Boats soon developed into [[keel boat]]s similar to today's wooden [[pleasure craft]].
At about the same time, the first navigators began to use animal skins or woven fabrics as [[sail]]s. Affixed to the top of a pole set vertically in a boat, these sails gave early ships great range. This allowed man to explore widely, allowing, for example the settlement of [[Oceania]] about 3,000 years ago.
<!--note:this article needs historic info added!-->
The [[ancient Egypt]]ians were perfectly at ease building sailboats. A remarkable example of their [[shipbuilding]] skills was the [[Khufu ship]], a vessel {{convert|143|ft|m}} in length entombed at the foot of the [[Great Pyramid of Giza]] around 2,500 BC and found intact in 1954. According to [[Herodotus]], the Egyptians made the first circumnavigation of Africa around 600 BC.
The [[Phoenician]]s and [[Ancient Greece|Greeks]] gradually mastered navigation at sea aboard [[trireme]]s, exploring and colonizing the [[Mediterranean]] via ship. Around 340 BC, the Greek [[navigator]] [[Pytheas of Massalia]] ventured from Greece to [[Western Europe]] and [[Great Britain]].<ref name="eb703">Chisholm, 1911:703.</ref>
Before the introduction of the compass, [[celestial navigation]] was the main method for navigation at sea. In China, early versions of the [[magnetic compass]] were being developed and used in navigation between 1040 and 1117.<ref>Li Shu-hua, “Origine de la Boussole 11. Aimant et Boussole,” ''Isis'', Vol. 45, No. 2. (Jul., 1954), p.181</ref> The true mariner's compass, using a pivoting needle in a dry box, was invented in Europe no later than 1300.<ref>Frederic C. Lane, “The Economic Meaning of the Invention of the Compass,” ''The American Historical Review'', Vol. 68, No. 3. (Apr., 1963), p.615ff.</ref><ref name="eb284">Chisholm, 1911:284.</ref>
===Through the Renaissance===
[[Image:Santa-Maria.jpg|thumb|right|The [[carrack]] [[Santa María (ship)|''Santa María'']] of [[Christopher Columbus]]]]
Until the [[Renaissance]], navigational technology remained comparatively primitive. This absence of technology didn't prevent some civilizations from becoming sea powers. Examples include the maritime republics of [[Republic of Genoa|Genoa]] and [[Republic of Venice|Venice]], and the [[Byzantine navy]]. The [[Viking]]s used their [[knarr]]s to explore [[North America]], trade in the [[Baltic Sea]] and plunder many of the coastal regions of Western Europe.
Towards the end of the fourteenth century, ships like the [[carrack]] began to develop towers on the bow and stern. These towers decreased the vessel's stability, and in the fifteenth century, [[caravel]]s became more widely used. The towers were gradually replaced by the [[forecastle]] and [[stern]]castle, as in the carrack [[Santa María (ship)|''Santa María'']] of [[Christopher Columbus]]. This increased [[freeboard]] allowed another innovation: the freeing port, and the artillery associated with it.
In the sixteenth century, the use of freeboard and freeing ports become widespread on [[galleon]]s. The English modified their vessels to maximize their firepower and demonstrated the effectiveness of their doctrine, in 1588, by defeating the [[Spanish Armada]].
[[Image:Atakebune2.jpg|thumb|right|A Japanese [[atakebune]] from the 16th century]]At this time, ships were developing in Asia in much the same way as Europe. [[Japan]] used defensive naval techniques in the [[Mongol invasions of Japan]] in 1281. It is likely that the Mongols of the time took advantage of both European and Asian shipbuilding techniques. In Japan, during the [[Sengoku era]] from the fifteenth to seventeenth century, the great struggle for feudal supremacy was fought, in part, by coastal fleets of several hundred boats, including the [[atakebune]].
Fifty years before Christopher Columbus, Chinese navigator [[Zheng He]] traveled the world at the head of what was for the time a huge armada. The largest of his ships had nine masts, were {{convert|130|m|ft}} long and had a beam of {{convert|55|m|ft}}. His fleet carried 30,000 men aboard 70 vessels, with the goal of bringing glory to the Chinese emperor.
===Specialization and modernization===
[[Image:Redoutable.jpg|thumb|right|The British ''[[HMS Temeraire (1798)|Temeraire]]'' and French ships ''[[French ship Redoutable (1791)|Redoutable]]'' and ''[[French ship Bucentaure (1804)|Bucentaure]]'' at the [[Battle of Trafalgar]]]]
Parallel to the development of warships, ships in service of marine fishery and trade also developed in the period between antiquity and the Renaissance. Still primarily a coastal endeavor, fishing is largely practiced by individuals <!---there has to be a better way to say this!-->with little other money using small boats.
Maritime trade was driven by the development of shipping companies with significant financial resources. Canal barges, towed by draft animals on an adjacent [[towpath]], contended with the [[railway]] up to and past the early days of the [[industrial revolution]]. Flat-bottomed and flexible [[scow]] boats also became widely used for transporting small cargoes. Mercantile trade went hand-in-hand with exploration, which is self-financing by the commercial benefits of exploration.
During the first half of the eighteenth century, the [[French Navy]] began to develop a new type of vessel, featuring seventy-four guns. This type of ship became the backbone of all European fighting fleets. These ships were {{convert|56|m|ft}} long and their construction required 2,800 oak trees and {{convert|40|km|mi}} of rope; they carried a crew of about 800 sailors and soldiers.
[[Image:Yacht and tugboat.jpg|thumb|left|A small [[pleasure boat]] and a [[tugboat]] in [[Rotterdam]]]]
Ship designs stayed fairly unchanged until the late nineteenth century. The industrial revolution, new mechanical methods of propulsion, and the ability to construct ships from metal triggered an explosion in ship design. Factors including the quest for more efficient ships, the end of long running and wasteful maritime conflicts, and the increased financial capacity of industrial powers created an avalanche of more specialized boats and ships. Ships built for entirely new functions, such as firefighting, rescue, and research, also began to appear.
In light of this, classification of vessels by type or function can be difficult. Even using very broad functional classifications such as fishery, trade, military, and exploration fails to classify most of the old ships. This difficulty is increased by the fact that the terms such as sloop and frigate are used by old and new ships alike, and often the modern vessels sometimes have little in common with their predecessors.
===Today===
Boats and ships remain essential tools for [[international trade|international]] and [[domestic trade]], [[national security]] and cultural purposes.
In 2007, the world's fleet included 34,882 commercial vessels with [[gross tonnage]] of more than 1,000 [[ton (volume)|tons]], totaling 1.04 billion tons. These ships carried 7.4 billion tons of cargo in 2006, a sum that grew by 8% over the previous year. In terms of tonnage, 37.5% of these ships are [[tanker (ship)|tanker]]s, 35.8% are [[bulk carrier]]s, 10.9% [[container ships]] and 10.3% [[general cargo ship]]s.
In 2002, there were 1,240 [[warship]]s operating in the world, not counting small vessels such as [[patrol boat]]s. <!--Adding total tonnage before this next sentence would make it clearer!-->The [[United States]] accounted for 3 million tons worth of these vessels, [[Russia]] 1.35 million tons, the [[United Kingdom]] 504,660 tons and [[China]] 402,830 tons. The twentieth century saw many naval engagements during the two [[world war]]s, the [[Cold War]], and the rise to power of naval forces of the two blocs. The world's major powers have recently used their naval power in cases such as the [[United Kingdom]] in the [[Falkland Islands]] and the [[United States]] in [[Iraq]].
[[Image:Fuglafjordur fishing boats, Faroe Islands.JPG|thumb|right|The harbor at [[Fuglafjørður]], [[Faroe Islands]] shows seven typical [[Faroe boat]]s used for fishing.]]
The size of the world's [[fishing fleet]] is more difficult to estimate. The largest of these are counted as commercial vessels, but the smallest are legion. [[Fishing vessel]]s can be found in most seaside villages in the world. In 1997, the United Nations [[Food and Agriculture Organization]] identified 2.285 million fishing vessels worldwide. An estimated 132.2 million tonnes of fish and shellfish were produced in 2003. In 1990, 29 million fishermen were active in the world.
==Types of ship==
Ships are difficult to classify, mainly because there are so many criteria to base classification on. Classification systems exist that use criteria such as:
* The number of hulls, giving categories like monohull, catamaran, trimaran.
* The shape and size, giving categories like dinghy, keelboat, and icebreaker.
* The building materials used, giving steel, aluminum, wood, fiberglass, and plastic.
* The type of propulsion system used, giving human-propelled, mechanical, and sails.
* The epoch in which the vessel was used, triremes of Ancient Greece, man' o' wars, eighteenth century.
* The geographic origin of the vessel, many vessels are associated with a particular region, such as the [[pinnace]] of Northern Europe, the [[gondola]]s of [[Venice]], and the [[junk (ship)|junks]] of China.
* The manufacturer, series, or class.
Another way to categorize ships and boats is based on their use, as described by Paulet and Presles.<ref name="paulet">{{cite book |last=Paulet |first=Dominique |coauthors=Presles ,Dominique |editor= |others= |title=Architecture navale, connaissance et pratique |origdate= |origyear= |accessyear= |year=1999 |publisher=Éditions de la Villette |location=Paris |language=Français |isbn=2-903539-46-4 }}</ref> This system includes military ships, commercial vessels, fishing boats, pleasure craft and competitive boats. In this section, ships are classified using the first four of those categories, and adding a section for lake and river boats, and one for vessels which fall outside these categories.
===Commercial vessels===
Commercial vessels or [[merchant ship]]s can be divided into three broad categories: [[cargo ship]]s, [[passenger ship]]s, and special-purpose ships.<ref name="unctadxii">UNCTAD 2007, p. ''xii'' uses a similar, but slightly more detailed classification system.</ref> Cargo ships transport dry and liquid cargo. Dry cargo can be transported in bulk by [[bulk carrier]]s, packed directly onto a [[general cargo ship]] in break-bulk, packed in [[shipping container]]s as aboard a [[container ship]], or driven aboard as in [[roll-on roll-off ship]]s. Liquid cargo is generally carried in bulk aboard tankers, such as [[oil tanker]]s, [[chemical tanker]]s and [[LNG tanker]]s.
Passenger ships range in size from small river ferries to giant [[cruise ship]]s. This type of vessel includes [[ferry|ferries]], which move passengers and vehicles on short trips; [[ocean liner]]s, which carry passengers on one-way trips; and cruise ships, which typically transport passengers on round-trip voyages promoting leisure activities onboard and in the ports they visit.
Special-purpose vessels are not used for transport but are designed to perform other specific tasks. Examples include [[tugboats]], [[pilot boat]]s, [[rescue boats]], [[cable ship]]s, [[research vessel]]s, [[survey vessel]]s, and [[ice breaker]]s.
Most commercial vessels have full hull-forms to maximize cargo capacity.{{cn|date=April 2008}} Hulls are usually made of steel, although aluminum can be used on faster craft, and fiberglass on the smallest service vessels.{{cn|date=April 2008}} Commercial vessels generally have a crew headed by a [[captain (nautical)|captain]], with [[deck officer]]s and [[marine engineer]]s on larger vessels. Special-purpose vessels often have specialized crew if necessary, for example scientists aboard [[research vessel]]s. Commercial vessels are typically powered by a single propeller driven by a [[diesel engine]].{{cn|date=April 2008}} Vessels which operate at the higher end of the speed spectrum may use [[pump-jet engine]]s or sometimes [[gas turbine engine]]s.{{cn|date=April 2008}}
<center><gallery>
Image:Line0534.jpg|Two modern [[container ship]]s in [[San Francisco]]
Image:Hkstarferry.JPG|A [[ferry]] in [[Hong-Kong]]
Image:Pilot boat.JPG|A [[pilot boat]] near the port of [[Rotterdam]]
Image:IFREMER - Pourquoi pas ?.JPG|The [[research vessel]] [[Pourquoi Pas? (2005)|''Pourquoi pas?'']] at [[Brest (France)|Brest]], [[France]]
</gallery></center>
===Military vessels===
There are many [[List of types of naval vessels|types of naval vessels]] currently and through history. Modern naval vessels can be broken down into three categories: [[List of naval ship classes in service|warships]], [[List of submarine classes in service|submarines]], and [[List of auxiliary ship classes in service|support and auxiliary vessels]].
Modern warships are generally divided into seven main categories, which are: [[aircraft carrier]]s, [[cruiser]]s, [[destroyer]]s, [[frigate]]s, [[corvette]]s, [[submarine]]s and [[amphibious assault ship]]s. [[Battleship]]s encompass an eighth category, but are not in current service with any navy in the world.<ref name="usntypes">With the addition of corvettes, this is the categorization used at {{cite web |url=http://www.navy.mil/navydata/our_ships.asp |title=U.S. Navy Ships |accessdate=2008-04-20 |author=United States Navy |authorlink=United States Navy |publisher=United States Navy }}</ref>
Most military submarines are either [[attack submarine]]s or [[ballistic submarine]]s. Until [[World War Two]], the primary role of the diesel/electric submarine was anti-ship warfare, inserting and removing covert agents and military forces, and intelligence-gathering. With the development of the homing torpedo, better [[sonar]] systems, and [[Nuclear navy|nuclear propulsion]], submarines also became able to effectively hunt each other. The development of [[Submarine-launched ballistic missile|submarine-launched nuclear missiles]] and submarine-launched [[cruise missiles]] gave submarines a substantial and long-ranged ability to attack both land and sea targets with a variety of weapons ranging from [[cluster bomb]]s to [[nuclear weapon]]s.
Most [[Navy|navies]] also include many types of support and auxiliary vessels, such as [[minesweeper (ship)|minesweeper]]s, [[patrol boat]]s, [[OPV (naval)|offshore patrol vessels]], [[replenishment ship]]s , and [[hospital ship]]s which are designated [[healthcare|medical treatment]] facilities.<ref>[http://wordnet.princeton.edu/perl/webwn?s=hospital%20ship Hospital Ship] (definition via [[WordNet]], [[Princeton University]])</ref>
Naval vessels usually have fine hulls to maximize speed and maneuverability.{{cn|date=April 2008}} They also usually have advanced electronics and communication systems, as well as weapons.
<center><gallery>
Image:Carrier.750pix.jpg|American [[aircraft carrier]] ''Harry S. Truman'' and a [[replenishment ship]]
Image:Uss iowa bb-61 pr.jpg|American battleship ''[[USS Iowa (BB-61)|USS Iowa]]'' fires an artillery salvo
Image:FS Rapiere.jpg|French landing craft ''Rapière'' near Toulon
</gallery></center>
</font>
===Fishing vessels===
Fishing vessels are a subset of commercial vessels, but generally small in size and often subject to different regulations and classification. They are distinguished by several criteria: the type of fish they catch, the fishing method used, geographical origin, and technical features such as rigging.
Commercial fishermen harvest many aquatic species, from [[tuna]], [[cod]], and [[salmon]] to [[shrimp]], [[krill]], [[lobster]], [[clam]]s, [[squid]] and [[crab]], in various [[fishery|fisheries]] for these species.
Modern commercial fishermen use many methods. One is fishing by [[Fishing net|nets]], such as [[Seine (fishing)|purse seine]], [[beach seine]], lift nets, [[gillnet]]s, or entangling nets. Another is [[trawl]]ing, including [[Bottom trawling|bottom trawl]]. [[Fish hook|Hooks]] and lines are used in methods like [[long-line fishing]] and [[hand-line fishing]]). Another method is the use of [[fishing trap]].
Fishing boats are generally small, often little more than {{convert|30|m|ft}}) but up to {{convert|100|m|ft}} for a large tuna or [[whaling ship]]. They feature holds large enough to keep a good-sized catch. The fish can then simply be stored on ice. Aboard a [[fish processing vessel]], they can be made ready for market and sold more quickly once the ship makes port.
The simplest fishing boats have a small cabin with a saloon, a deck designed to accommodate fishing, and fishing equipment such as nets and lines. Trawlers have additional gear such as winches and arms. Other devices are used, such as a rear ramp on a stern-trawler, and a skiff on a tuna seiner.
<center><gallery>
Image:Fishing boat in Cap-Haitien.jpg|Fishing boat in [[Cap-Haïtien]], [[Haïti]]
Image:Chalutier.JPG|A [[Commercial trawler|trawler]] at [[Saint-Nazaire]]
Image:Bateau ostreicole.jpg|An oyster boat at [[La Trinité-sur-Mer]]
Image:Albatun Dod.jpg|The ''Albatun Dos'', a tuna boat at work near [[Victoria, Seychelles]]
</gallery></center>
===Inland and coastal boats===
Many types of boats and ships are designed for inland and coastal waterways. These are the vessels that trade upon the lakes, rivers and canals.
Barges are a prime example of inland vessels. Flat-bottomed [[boat]]s built to transport heavy goods, most barges are not self-propelled and need to be moved by [[tugboat]]s towing or [[towboats]] pushing them. Barges towed along canals by draft animals on an adjacent [[towpath]] contended with the [[railway]] in the early [[industrial revolution]] but [[history of the British canal system|were outcompeted]] in the carriage of high value items due to the higher speed, falling costs, and route flexibility of [[rail transport]].
[[Riverboat]]s and [[ferry boat|inland ferries]] are specially designed to carry passengers, cargo, or both in the challenging river environment. Rivers present special hazards to vessels. They usually have varying water flows that alternately lead to high speed water flows or protruding rock hazards. Changing siltation patterns may cause the sudden appearance of shoal waters, and often floating or sunken logs and trees (called snags) can endanger the hulls and propulsion of riverboats. Riverboats are generally of shallow draft, being broad of beam and rather square in plan, with a low freeboard and high topsides. Riverboats can survive with this type of configuration as they do not have to withstand the high winds or large waves that are seen on large lakes, seas, or oceans.
[[Lake freighter]]s, also called lakers, are [[cargo]] vessels that ply the [[Great Lakes]]. The most well-known is the {{SS|Edmund Fitzgerald}}, the latest major vessel to be wrecked on the Lakes. These vessels are traditionally called boats, not ships. Visiting ocean-going vessels are called "salties." Due to their additional [[Beam (nautical)|beam]], very large salties are never seen inland of the [[Saint Lawrence Seaway]]. Because the largest of the [[Soo Locks]] is larger than any Seaway lock, salties that can pass through the Seaway may travel anywhere in the Great Lakes. Because of their deeper draft, salties may accept partial loads on the Great Lakes, "topping off" when they have exited the Seaway. Similarly, the largest lakers are confined to the Upper Lakes ([[Lake Superior|Superior]], [[Lake Michigan|Michigan]], [[Lake Huron|Huron]], [[Lake Erie|Erie]]) because they are too large to use the Seaway locks, beginning at the [[Welland Canal]] that bypasses the [[Niagara River]].
Since the [[freshwater]] lakes are less corrosive to ships than the [[Seawater|salt water]] of the oceans, lakers tend to last much longer than ocean freighters. Lakers older than 50 years are not unusual, and account for more than half of the fleet.{{Fact|date=February 2007}} The ''St. Mary's Challenger'', built in 1906 as the ''William P Snyder'', is the oldest laker still working on the Lakes. Similarly, the ''E.M. Ford'', built in 1898 as the ''Presque Isle'', was sailing the lakes 98 years later in 1996. As of 2007 the ''Ford'' was still afloat as a stationary transfer vessel at a riverside cement silo in [[Saginaw, Michigan]].
<center><gallery>
Image:Rheinschiff Temptation I.JPG|[[Riverboat]] ''Temptation'' on the [[Rhine]]
Image:RiverboatNatchez.jpg|Riverboat ''Natchez'' on the [[Mississippi River]]
Image:Paris bateau parisien DSC00737.jpg|Commuter boat on the [[Seine]]
Image:SSEdmundFitzgerald.jpg|The [[lake freighter]] {{SS|Edmund Fitzgerald}}
</gallery></center>
===Other===
The wide variety of vessels at work on the earth's waters defy a simple classification scheme. A representative few that fail to fit into the above categories include:
* Historical boats, frequently used as [[museum ships]], [[training ship]]s, or as good-will ambassadors of a country abroad.
* [[Houseboat]]s, floating structures used as dwellings.
* Scientific, technical, and industrial vessels such as [[oil platform|mobile offshore drilling units]], offshore wind farms, [[survey ship]]s, and [[research vessel]]s.
* [[Submarine]]s, for underwater navigation and exploration
<center><gallery>
Image:Dar Pomorza pod zaglami s.jpg|The Polish sailing frigate ''[[Dar Pomorza]]''
Image:House boat, backwaters.JPG|A [[houseboat]] near [[Kerala]]
Image:Mobile-offshore-drilling-unit.gif|A mobile offshore drilling unit in the [[Gulf of Mexico]]
Image:Monaco-YellowSubmarine.jpg|A [[bathyscaphe]] at the oceanographic museum in [[Monaco]]
</gallery></center>
==Architecture==
{{see|Naval architecture}}
Some components exist in vessels of any size and purpose. Every vessel has a hull of sorts. Every vessel has some sort of propulsion, whether it's a pole, an ox, or a nuclear reactor. Most vessels have some sort of steering system. Other characteristics are common, but not as universal, such as compartments, holds, a superstructure, and equipment such as anchors and winches.
===The hull===
[[Image:CargoVslBadWeather.JPG|thumb|right|A ship's hull endures harsh conditions at sea, as illustrated by this [[reefer ship]] in bad weather.]]
For a ship to float, its weight must be less than that of the water displaced by the ship's hull. There are many types of hulls, from logs lashed together to form a raft to the advanced hulls of [[America's Cup]] sailboats. A vessel may have a single hull (called a monohull design), two in the case of [[catamaran]]s, or three in the case of [[trimaran]]s. Vessels with more than three hulls are rare, but some experiments have been conducted with designs such as pentamarans. Multiple hulls are generally parallel to each other and connected by rigid arms.
Hulls have several elements. The [[bow (ship)|bow]] is the foremost part of the hull. Many ships feature a [[bulbous bow]]. The [[keel]] is at the very bottom of the hull, extending the entire length of the ship. The rear part of the hull is known as the [[stern]], and many hulls have a flat back known as a [[transom (nautical)|transom]]. Common hull appendages include [[propeller]]s for propulsion, [[rudder]]s for steering, and [[Stabilizer (ship)|stabilizers]] to quell a ship's rolling motion. Other hull features can be related to the vessel's work, such as fishing gear and [[sonar|sonar dome]]s.
Hulls are subject to various hydrostatic and hydrodynamic constraints. The key hydrostatic constraint is that it must be able to support the entire weight of the boat, and maintain stability even with often unevenly distributed weight. Hydrodynamic constraints include the ability to withstand shock waves, weather collisions and groundings.
Older ships and pleasure craft often have or had wooden hulls. Steel is used for most commercial vessels. Aluminium is frequently used for fast vessels, and [[composite material]]s are often found in sailboats and pleasure craft. Some ships have been made with [[Concrete ship|concrete hulls]].
===Propulsion systems===
[[Image:Mozambique - traditional sailboat.jpg|thumb|right|A fishing boat uses a traditional propulsion system in [[Mozambique]]]]
[[Image:Rotorship Alcyone in harbour.jpg|thumb|right|The [[turbosail]], a hybrid propulsion system invented by [[Jacques-Yves Cousteau]]]]
Propulsion systems for ships and boats vary from the simple paddle to the largest diesel engines in the world. These systems fall into three categories: human propulsion, sailing, and mechanical propulsion. Human propulsion includes the pole, still widely used in marshy areas, rowing which was used even on large [[galley]]s, and the pedals. In modern times, human propulsion is found mainly on small boats or as auxiliary propulsion on sailboats.
Propulsion by sail generally consists of a sail hoisted on an erect mast, supported by stays and spars and controlled by ropes. Sail systems were the dominant form of propulsion until the nineteenth century. They are now generally used for recreation and racing, although experimental sail systems, such as the [[turbosail]] and [[SkySails]] systems, have been used on larger modern vessels for fuel savings.
Mechanical propulsion systems generally consist of a motor or engine turning a [[propeller]]. [[Steam engine]]s were first used for this purpose, but have mostly been replaced by [[two-stroke engine|two-stroke]] or [[four-stroke engine|four-stroke]] diesel engines, outboard motors, and [[gas turbine engine]]s on faster ships. Electric motors have sometimes been used, such as on submarines. Nuclear reactors are sometimes employed to propel [[warship]]s and [[icebreaker]]s.
There are many variations of propeller systems, including twin, contra-rotating, controllable-pitch, and nozzle-style propellers. Smaller vessels tend to have a single propeller. Aircraft carriers uses up to four propellers, supplemented with [[bow thruster|bow-]] and stern-thrusters. Power is transmitted from the engine to the propeller by way of a propeller shaft, which may or may not be connected to a gearbox.
====Pre-mechanisation====
[[Image:WorldShips1460.jpg|thumb|Ships of the world in 1460, according to the [[Fra Mauro map]]]]
Until the application of the [[steam engine]] to ships in the early 19th century, oars propelled [[galley]]s, or the wind propelled [[sailing ship]]s. Before mechanisation, merchant ships always used sail, but as long as [[naval warfare]] depended on ships closing to [[Battering ram|ram]] or to fight hand-to-hand, galleys dominated in marine conflicts because of their maneuverability and speed. The [[Ancient Greece|Greek]] navies that fought in the [[Peloponnesian War]] used [[trireme]]s, as did the [[Ancient Rome|Romans]] at the [[Battle of Actium]]. The use of large numbers of [[cannon]] from the 16th century meant that maneuverability took second place to broadside weight; this led to the dominance of the sail-powered warship.
====Reciprocating steam engines====
The development of piston-engined steamships was a complex process. Early steamships were fueled by wood, later ones by coal or fuel oil. Early ships used stern or side [[paddle wheel]]s, while later ones used screw propellers.
The first commercial success accrued to [[Robert Fulton]]'s ''North River Steamboat'' (often called [[PS Clermont|''Clermont'']]) in the US in 1807, followed in [[Europe]] by the 45-foot [[PS Comet|''Comet'']] of 1812. Steam propulsion progressed considerably over the rest of the 19th century. Notable developments included the steam surface [[condenser]], which eliminated the use of sea water (salt water) in the ship's boilers. This permitted higher steam pressures, and thus the use of higher efficiency [[Steam engine#Multiple expansion|multiple expansion]] (compound) engines. As the means of transmitting the engine's power, paddle wheels gave way to more efficient screw propellers.
====Steam turbines====
[[Image:SS Ukkopekka steam engine.jpg|thumb|[[S/S Ukkopekka|SS ''Ukkopekka'']] uses a triple expansion [[steam engine]]]]
Steam turbines were fueled by [[coal]] or, later, [[fuel oil]] or [[nuclear power]]. The marine [[steam turbine]] developed by Sir [[Charles Algernon Parsons]] raised the power to weight ratio. He achieved publicity by demonstrating it unofficially in the 100-foot ''[[Turbinia]]'' at the [[Spithead]] [[Fleet Review, Royal Navy#Queen Victoria|naval review]] in 1897. This facilitated a generation of high-speed liners in the first half of the 20th century and rendered the reciprocating steam engine obsolete, first in warships and later in merchant vessels.
In the early 20th century, heavy fuel oil came into more general use and began to replace coal as the fuel of choice in steamships. Its great advantages were convenience, reduced manning due to removing the need for trimmers and stokers, and reduced space needed for fuel bunkers.
In the second half of the 20th century, rising fuel costs almost led to the demise of the steam turbine. Most new ships since around 1960 have been built with [[diesel engine]]s. The last major passenger ship built with steam turbines was the ''[[Pacific Sky|Fairsky]]'', launched in 1984. Similarly, many steam ships were re-engined to improve fuel efficiency. One high profile example was the 1968 built ''[[Queen Elizabeth 2]]'' which had her steam turbines replaced with a diesel-electric propulsion plant in 1986.
Most new-build ships with steam turbines are specialist vessels such as nuclear-powered vessels, and certain merchant vessels (notably [[Liquefied Natural Gas]] (LNG) and coal carriers) where the cargo can be used as bunker fuel.
=====LNG carriers=====
New [[LNG carrier]]s (a high growth area of shipping) continue to be built with steam turbines. The natural gas is stored in a liquid state in [[cryogenics|cryogenic]] vessels aboard these ships, and a small amount of 'boil off' gas is needed to maintain the pressure and temperature inside the vessels within operating limits. The 'boil off' gas provides the fuel for the ship's boilers, which provide steam for the turbines, the simplest way to deal with the gas. Technology to operate [[internal combustion engine]]s (modified marine two-stroke diesel engines) on this gas has improved, however, so such engines are starting to appear in LNG carriers; with their greater thermal efficiency, less gas is burnt. Developments have also been made in the process of re-liquefying 'boil off' gas, letting it be returned to the cryogenic tanks. The financial returns on LNG are potentially greater than the cost of the marine-grade fuel oil burnt in conventional diesel engines, so the re-liquefaction process is starting to be used on diesel engine propelled LNG carriers. Another factor driving the change from turbines to diesel engines for LNG carriers is the shortage of steam turbine qualified seagoing engineers. With the lack of turbine powered ships in other shipping sectors, and the rapid rise in size of the worldwide LNG fleet, not enough have been trained to meet the demand. It may be that the days are numbered for marine steam turbine propulsion systems, even though all but sixteen of the orders for new LNG carriers at the end of 2004 were for steam turbine propelled ships.<ref>[http://www.informare.it/news/forum/2005/brs/lng-auk.asp inforMARE - FORUM of Shipping and Logistics<!-- Bot generated title -->]</ref>
=====Nuclear-powered steam turbines=====
[[Image:NSsavannah-1962.gif|thumb|right|The [[NS Savannah|NS ''Savannah'']] was the first [[Nuclear marine propulsion|nuclear-powered]] cargo-passenger ship]]
In these vessels, the [[nuclear reactor|reactor]] heats steam to drive the turbines. Partly due to concerns about safety and waste disposal, nuclear propulsion is rare except in specialist vessels. In large [[aircraft carrier]]s, the space formerly used for ship's bunkerage could be used instead to bunker aviation fuel. In [[submarine]]s, the ability to run submerged at high speed and in relative quiet for long periods holds obvious advantages. A few [[cruisers]] have also employed nuclear power; as of 2006, the only ones remaining in service are the [[Russia]]n [[Kirov class battlecruiser|''Kirov'' class]]. An example of a non-military ship with [[nuclear marine propulsion]] is the [[Arktika class icebreaker|''Arktika'' class icebreaker]] with 75,000 shaft horsepower. Commercial experiments such as the [[NS Savannah|NS ''Savannah'']] proved uneconomical compared with conventional propulsion.
====Reciprocating diesel engines====
[[Image:MainEngine1.JPG|thumb|right|A modern [[diesel engine]] aboard a cargo ship]]
[[Image:Two Main Engines, V12.jpg|thumb|right|A bird's eye view of a ship's engineroom]]
About 99% of modern ships use diesel reciprocating engines{{Fact|date=May 2007}}. The rotating crankshaft can power the propeller directly for slow speed engines, via a gearbox for medium and high speed engines, or via an alternator and electric motor in diesel-electric vessels.
The reciprocating marine diesel engine first came into use in 1903 when the [[diesel electric]] rivertanker [[Vandal (ship)|''Vandal'']] was put in service by [[Branobel]]. Diesel engines soon offered greater efficiency than the steam turbine, but for many years had an inferior power-to-space ratio.
Diesel engines today are broadly classified according to
* Their operating cycle: [[two-stroke]] or [[four-stroke]]
* Their construction: [[Crosshead]], [[Trunk engine|trunk]], or [[Opposed piston engine|opposed piston]]
* Their speed
** Slow speed: any engine with a maximum operating speed up to 300 revs/minute, although most large 2-stroke slow speed diesel engines operate below 120 revs/minute. Some very long stroke engines have a maximum speed of around 80 revs/minute. The largest, most powerful engines in the world are slow speed, two stroke, crosshead diesels.
** Medium speed: any engine with a maximum operating speed in the range 300-900 revs/minute. Many modern 4-stroke medium speed diesel engines have a maximum operating speed of around 500 rpm.
** High speed: any engine with a maximum operating speed above 900 revs/minute.
Most modern larger merchant ships use either slow speed, two stroke, crosshead engines, or medium speed, four stroke, trunk engines. Some smaller vessels may use high speed diesel engines.
The size of the different types of engines is an important factor in selecting what will be installed in a new ship. Slow speed two-stroke engines are much taller, but the area needed, length and width, is smaller than that needed for four-stroke medium speed diesel engines. As space higher up in passenger ships and ferries is at a premium, these ships tend to use multiple medium speed engines resulting in a longer, lower engine room than that needed for two-stroke diesel engines. Multiple engine installations also give redundancy in the event of mechanical failure of one or more engines and greater efficiency over a wider range of operating conditions.
As modern ships' propellers are at their most efficient at the operating speed of most slow speed diesel engines, ships with these engines do not generally need gearboxes. Usually such propulsion systems consist of either one or two propeller shafts each with its own direct drive engine. Ships propelled by medium or high speed diesel engines may have one or two (sometimes more) propellers, commonly with one or more engines driving each propeller shaft through a gearbox. Where more than one engine is geared to a single shaft, each engine will most likely drive through a clutch, allowing engines not being used to be disconnected from the gearbox while others keep running. This arrangement lets maintenance be carried out while under way, even far from port.
====Gas turbines====
Many warships built since the 1960s have used [[gas turbine]]s for propulsion, as have a few passenger ships, like the [[jetfoil]]. Gas turbines are commonly used in combination with other types of engine. Most recently, the ''[[Queen Mary 2]]'' has had gas turbines installed in addition to [[diesel engines]]. Due to their poor thermal efficiency at low power (cruising) output, it is common for ships using them to have diesel engines for cruising, with gas turbines reserved for when higher speeds are needed. Some warships and a few modern cruise ships have also used the steam turbines to improve the efficiency of their gas turbines in a [[combined cycle]], where wasted heat from a gas turbine exhaust is utilized to boil water and create steam for driving a steam turbine. In such combined cycles, thermal efficiency can be the same or slightly greater than that of diesel engines alone; however, the grade of fuel needed for these gas turbines is far more costly than that needed for the diesel engines, so the running costs are still higher.
===Steering systems===
[[Image:Ferry-rudder-and-propeller.jpg|thumb|right|The rudder and propeller on a newly built ferry]]
On boats with simple propulsion systems, such as paddles, steering systems may not be necessary. In more advanced designs, such as boats propelled by engines or sails, a steering system becomes more necessary. The most common is a rudder, a submerged plane located at the rear of the hull. Rudders are rotated to generate a lateral force which turns the boat. Rudders can be rotated by a [[tiller]], manual wheels, or electro-hydraulic systems. [[Autopilot]] systems combine mechanical rudders with navigation systems.
Some propulsion systems are inherently steering systems. Examples include the [[outboard motor]], the [[bow thruster]], and the [[Z-drive]]. Some sails, such as jibs and the [[Mizzen|mizzen sail]] on a [[ketch rig]], are used more for steering than propulsion.
===Holds, compartments, and the superstructure===
Larger boats and ships generally have multiple decks and compartments. Separate [[berthing]]s and [[Head (watercraft)|head]]s are found on sailboats over about {{convert|25|ft|m}}. Fishing boats and cargo ships typically have one or more cargo holds. Most larger vessels have an engine room, a galley, and various compartments for work. Tanks are used to store fuel, engine oil, and fresh water. Ballast tanks are equipped to change a ship's trim and modify its stability.
Superstructures are found above the main deck. On sailboats, these are usually very low. On modern cargo ships, they are almost always located near the ship's stern. On passenger ships and warships, the superstructure generally extends far forward.
===Equipment===
Shipboard equipment varies from ship to ship depending on such factors as the ship's era, design, area of operation, and purpose. Some types of equipment that are widely found include:
* [[Mast]]s can be the home of antennas, navigation lights, radar transponders, fog signals, and similar devices often required by law.
* [[Ground tackle]] includes equipment such as mooring winches, windlasses, and anchors. Anchors are used to [[mooring (watercraft)|moor]] ships in shallow water. They are connected to the ship by a rope or chain. On larger vessels, the chain runs through a [[hawsepipe]].
* Cargo equipment such as [[crane]]s and [[cargo boom]]s are used to load and unload cargo and ship's stores.
* Safety equipment such as [[lifeboat]]s, [[liferaft]]s, [[fire extinguisher]]s, and [[survival suit]]s are carried aboard many vessels for emergency use.
==Design considerations==
===Hydrostatics===
[[Image:LCAC.JPG|thumb|right|Some vessels, like the [[LCAC]], can operate in a non-displacement mode.]]
Boats and ships are kept on (or slightly above) the water in three ways:
* For most vessels, known as displacement vessels, the vessel's weight is offset by that of the water displaced by the hull.
* For planing ships and boats, such as the hydrofoil, the lift developed by the movement of the foil through the water increases with the vessel's speed, until the vessel is foilbourne.
* For non-displacement craft such as [[hovercraft]] and [[air-cushion vehicle]]s, the vessel is suspended over the water by a cushion of high-pressure air it projects downwards against the surface of the water.
A vessel is in equilibrium when the upwards and downwards forces are of equal magnitude. As a vessel is lowered into the water its weight remains constant but the corresponding weight of water displaced by its hull increases. When the two forces are equal, the boat floats. If weight is evenly distributed throughout the vessel, it floats without trim or heel.
A vessel's stability is considered in both this [[Initial stability|hydrostatic]] sense as well as a [[Ship stability|hydrodynamic]] sense, when subjected to movement, rolling and pitching, and the action of waves and wind. Stability problems can lead to excessive pitching and rolling, and eventually capsizing and sinking.
===Hydrodynamics===
[[Image:Dona Delfina at Mazatlan.jpg|thumb|right|A system of waves forms as ''Dona Delfina'' gains speed and begins to plane.]]
The advance of a vessel through water is resisted by the water. This resistance can be broken down into several components, the main ones being the friction of the water on the hull and [[wave making resistance]]. To reduce resistance and therefore increase the speed for a given power, it is necessary to reduce the wetted surface and use submerged hull shapes that produce low amplitude waves. To do so, high-speed vessels are often more slender, with fewer or smaller appendages. The friction of the water is also reduced by regular maintenance of the hull to remove the sea creatures and algae that accumulate there. [[Antifouling]] paint is commonly used to assist in this. Advanced designs such as the [[bulbous bow]] assist in decreasing wave resistance.
A simple way of considering wave-making resistance is to look at the hull in relation to its wake. At speeds lower than the wave propagation speed, the wave rapidly dissipates to the sides. As the hull approaches the wave propagation speed, however, the wake at the bow begins to build up faster than it can dissipate, and so it grows in [[amplitude]]. Since the water is not able to "get out of the way of the hull fast enough", the hull, in essence, has to climb over or push through the bow wave. This results in an [[exponential function|exponential]] increase in resistance with increasing speed.
This [[hull speed]] is found by the formula:
<math>\mbox{knots} \approx 1.34 \times \sqrt{l \mbox{ft}}</math>
Or, in [[metric system|metric]] units:
<math>\mbox{knots} \approx 2.5 \times \sqrt{l \mbox{m}}</math>
When the vessel exceeds a speed/length ratio of 0.94, it starts to outrun most of its [[bow wave]], and the hull actually settles slightly in the water as it is now only supported by two wave peaks. As the vessel exceeds a speed/length ratio of 1.34, the hull speed, the wavelength is now longer than the hull, and the stern is no longer supported by the wake, causing the stern to squat, and the bow rise. The hull is now starting to climb its own bow wave, and resistance begins to increase at a very high rate. While it is possible to drive a displacement hull faster than a speed/length ratio of 1.34, it is prohibitively expensive to do so. Most large vessels operate at speed/length ratios well below that level, at speed/length ratios of under 1.0.
[[Image:Brosen shipsmovemensonthewave.svg|thumb||left|Vessels move along the three axes: 1. heave, 2. sway, 3. surge, 4. yaw, 5. pitching, 6. roll]]
For large projects with adequate funding, hydrodynamic resistance can be tested experimentally in a hull testing pool or using tools of [[computational fluid dynamics]].
Vessels are also subject to [[ocean surface wave]]s and [[sea swell]] as well as effects of [[wind]] and [[weather]]. These movements can be stressful for passengers and equipment, and must be controlled if possible. The rolling movement can be controlled, to an extent, by ballasting or by devices such as [[Stabilizer (ship)|fin stabilizers]]. Pitching movement is more difficult to limit and can be dangerous if the bow submerges in the waves, a phenomenon called pounding. Sometimes, ships must change course or speed to stop violent rolling or pitching.
==Lifecycle==
A ship will pass through several stages during its career. The first is usually an initial contract to build the ship, the details of which can vary widely based on relationships between the [[shipowner]]s, operators, [[naval architect|designers]] and the [[shipyard]]. Then, the design phase carried out by a naval architect. Then the ship is constructed in a shipyard. After construction, the vessel is launched and goes into service. Ships end their careers in a number of ways, ranging from [[shipwreck]]s to service as a [[museum ship]] to [[Ship breaking|the scrapyard]].
===Design===
[[Image:Lines plan en.svg|thumb|right|Lines plan for the hull of a basic cargo ship]]
A vessel's design starts with a specification, which a [[naval architect]] uses to create a project outline, assess required dimensions, and create a basic layout of spaces and a rough displacement. After this initial rough draft, the architect can create an initial hull design, a general profile and an initial overview of the ship's propulsion. At this stage, the designer can iterate on the ship's design, adding detail and refining the design at each stage.
The designer will typically produce an overall plan, a general specification describing the peculiarities of the vessel, and construction blueprints to be used at the building site. Designs for larger or more complex vessels may also include sail plans, electrical schematics, and plumbing and ventilation plans.
===Construction===
[[Image:Brosen northern side lauching2.jpg|thumb|right|A [[Ship naming and launching|ship launching]] at the Northern Shipyard in [[Gdansk, Poland]]]]
Ship construction takes place in a shipyard, and can last from a few months for a unit produced in series, to several years to reconstruct a wooden boat like the frigate ''Hermione'', to more than 10 years for an aircraft carrier. Hull materials and vessel size play a large part in determining the method of construction. The hull of a mass-produced fiberglass sailboat is constructed from a mold, while the steel hull of a cargo ship is made from large sections welded together as they are built.
Generally, construction starts with the hull, and on vessels over about 30 meters, by the laying of the keel. This is done in a dry dock or on land. Once the hull is assembled and painted, it is launched. The last stages, such as raising the superstructure and adding equipment and accommodation, can be done after the vessel is afloat.
Once completed, the vessel is delivered to the customer. [[Ship naming and launching|Ship launching]] is often a ceremony of some significance, and is usually when the vessel is formally named. A typical small rowboat can cost under US$100, $1,000 for a small speedboat, tens of thousands of dollars for a cruising sailboat, and about $2,000,000 for a [[Vendée Globe]] class sailboat. A {{convert|25|m|ft}} trawler may cost $2.5 million, and a 1,000-person-capacity high-speed passenger ferry can cost in the neighborhood of $50 million. A ship's cost partly depends on its complexity: a small, [[general cargo ship]] will cost $20 million, a [[Panamax]]-sized [[bulk carrier]] around $35 million, a [[supertanker]] around $105 million and a large [[LNG carrier]] nearly $200 million. The most expensive ships generally are so due to the cost of embedded electronics: a [[Seawolf class submarine|''Seawolf'' class submarine]] costs around $2 billion, and an aircraft carrier goes for about $3.5 billion.
===Repair and conversion===
[[Image:Able-seaman-scaling-winch.JPG|thumb|right|An [[able seaman]] uses a [[needlegun scaler]] while refurbishing a mooring winch at sea.]]Ships undergo nearly constant maintenance during their career, whether they be underway, pierside, or in some cases, in periods of reduced operating status between charters or shipping seasons.
Most ships do, however, require trips to special facilities such as a [[drydock]] at regular intervals. Some tasks often done at drydock include removing biological growths on the hull, [[sandblasting]] and repainting the hull, and replacing [[sacrificial anode]]s used to protect submerged equipment from corrosion. Major repairs to the propulsion and steering systems as well as major electrical systems are also often performed at dry dock.
Vessels that sustain major damage at sea may be repaired at a facility equipped for major repairs, such as a shipyard. Ships are may also be converted for a new purpose; [[oil tanker]]s are often converted into [[floating production storage and offloading unit]]s.
===End of service===
[[Image:Shipbreakingbangladesh.jpg|thumb|[[Shipbreaking]] near [[Chittagong]], [[Bangladesh]]]]
Most ocean-going cargo ships have a life expectancy of between 20 and 30 years. A sailboat made of plywood or fiberglass can last between 30 and 40 years. Solid wooden ships can last much longer but require regular maintenance. Carefully maintained steel-hulled yachts can have a lifespan of over 100 years.
As ships age, forces such as corrosion, osmosis, and rotting compromise hull strength, and a vessel becomes too dangerous to sail. At this point, it can be [[scuttling|scuttled]] at sea or [[Ship breaking|scrapped]] by [[shipbreaker]]s. Ships can also be used as [[museum ships]], or expended to construct [[breakwater]]s or [[artificial reef]]s.
Many ships do not make it to the scrapyard, and are lost in fires, collisions, [[ship grounding|grounding]], or sinking at sea.
== Measuring ships ==
One can [[Hull (watercraft)#Metrics|measure ships]] in terms of overall length, length of the ship at the waterline, beam (breadth), depth (distance between the crown of the weather deck and the top of the keelson), [[Draft (hull)|draft]] (distance between the highest waterline and the bottom of the ship) and [[tonnage]]. A number of different tonnage definitions exist and are used when describing merchant ships for the purpose of tolls, taxation, etc.
In Britain until Samuel Plimsoll's [[Merchant Shipping Act, 1876|Merchant Shipping Act of 1876]], ship-owners could load their vessels until their decks were almost awash, resulting in a dangerously unstable condition. Anyone who signed on to such a ship for a voyage and, upon realizing the danger, chose to leave the ship, could end up in [[jail]].
[[Samuel Plimsoll]], a [[Member of Parliament]], realised the problem and engaged some [[engineer]]s to derive a fairly simple [[formula]] to determine the position of a line on the side of any specific ship's hull which, when it reached the surface of the water during loading of cargo, meant the ship had reached its maximum safe loading level. To this day, that mark, called the "[[waterline|Plimsoll Line]]", exists on ships' sides, and consists of a [[circle]] with a horizontal line through the centre. On the Great Lakes of North America the circle is replaced with a diamond. Because different types of water (summer, fresh, tropical fresh, winter north Atlantic) have different densities, subsequent regulations required painting a group of lines forward of the Plimsoll mark to indicate the safe depth (or freeboard above the surface) to which a specific ship could load in water of various densities. Hence the "ladder" of lines seen forward of the Plimsoll mark to this day. This is called the "[[freeboard mark]]" or "[[waterline#load line|load line mark]]" in the [[marine industry]].
==Ship pollution==
[[Ship pollution]] is the pollution of air and [[water]] by [[shipping]]. It is a problem that has been accelerating as [[trade]] has become increasingly globalized, posing an increasing threat to the world’s oceans and waterways as [[globalization]] continues. It is expected that, “…shipping traffic to and from the [[USA]] is projected to double by 2020."<ref name="Watson">Watson, T. (2004, August 30). Ship pollution clouds USA's skies. ''USA Today''. Retrieved [[November 1]], [[2006]], from http://www.usatoday.com/news/nation/2004-08-30-ship-pollution_x.htm</ref> Because of increased traffic in ocean [[ports]], pollution from ships also directly affects coastal areas. The pollution produced affects [[biodiversity]], climate, food, and human health. However, the degree to which humans are polluting and how it affects the world is highly debated and has been a hot international topic for the past 30 years.
===Oil spills===
[[Image:OilCleanupAfterValdezSpill.jpeg|thumb|right| The [[Exxon Valdez oil spill|''Exxon Valdez'' spilled]] 10.8 million gallons of oil into Alaska's [[Prince William Sound]].<ref name = EVOSTC_FAQ> {{cite web| title = Frequently asked questions about the Exxon Valdez Oil Spill|url=http://www.evostc.state.ak.us/History/FAQ.htm|publisher =State of Alaska}}</ref>]]
Oil spills have devastating effects on the environment. Crude oil contains [[polycyclic aromatic hydrocarbons]] (PAHs) which are very difficult to clean up, and last for years in the [[sediment]] and marine environment.<ref name="Panetta">Panetta, L. E. (Chair) (2003). America's living oceans: charting a course for sea change [Electronic Version, CD] Pew Oceans Commission.</ref> Marine species constantly exposed to PAHs can exhibit developmental problems, susceptibility to disease, and abnormal reproductive cycles.
By the sheer amount of oil carried, modern oil tankers must be considered something of a threat to the environment. An oil tanker can carry {{convert|2|Moilbbl|m3}} of crude oil, or 62,000,000 gallons. This is more than six times the amount spilled in the widely known [[Exxon Valdez oil spill|''Exxon Valdez'' incident]]. In this spill, the ship ran aground and dumped 10.8 million gallons of oil into the ocean in March of 1989. Despite efforts of scientists, managers, and volunteers, over 400,000 [[seabirds]], about 1,000 [[sea otters]], and immense numbers of fish were killed.<ref name="Panetta"/>
The International Tanker Owners Pollution Federation has researched 9,351 accidental spills since 1974.<ref name="itopf">[http://www.itopf.com/information-services/data-and-statistics/statistics/ International Tanker Owners Pollution Federation Statistics]</ref> According to this study, most spills result from routine operations such as loading cargo, discharging cargo, and taking on fuel oil.<ref name="itopf"/> 91% of the operational oil spills were small, resulting in less than 7 tons per spill.<ref name="itopf"/> Spills resulting from accidents like collisions, groundings, hull failures, and explosions are much larger, with 84% of these involving losses of over 700 tons.<ref name="itopf"/>
Following the ''Exxon Valdez'' spill, the United States passed the [[Oil Pollution Act of 1990]] (OPA-90), which included a stipulation that all tankers entering its waters be [[Double-hulled tanker|double-hulled]] by 2015. Following the sinkings of the ''[[Erika (tanker)|Erika]]'' (1999) and ''[[Prestige oil spill|Prestige]]'' (2002), the [[European Union]] passed its own stringent anti-pollution packages (known as Erika I, II, and III), which require all tankers entering its waters to be double-hulled by 2010. The Erika packages are controversial because they introduced the new legal concept of "serious negligence".<ref>{{cite book |author=European Parliament |authorlink=European Parliament |coauthors= |editor= |others= |title=Directive 2005/35/EC of the European Parliament and of the Council of 7 September 2005 on ship-source pollution and on the introduction of penalties for infringements|origdate=2005 |origyear= |origmonth= |url=http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2005:255:0011:01:EN:HTML |format= |accessdate=2008-02-22 |accessyear= |accessmonth= |edition= |series= |date= |year= |month= |publisher= |location= |language= |isbn= |oclc= |doi= |id= |pages= |chapter= |chapterurl= |quote= }}</ref>
===Ballast water===
[[Image:Ship pumping ballast water.jpg|thumb|right|A cargo ship pumps ballast water over the side]]
When a large vessel such as a [[container ship]] or an oil tanker unloads cargo, sea-water is pumped into compartments in the hull to help stabilize and balance the ship. During loading, this ballast water is pumped out from these compartments.
One of the problems with ballast water transfer is the transport of harmful organisms. Meinesz<ref name="Meinesz">Meinesz, A. (2003). Deep Sea Invasion. ''The Impact of Invasive Species''. PBS: NOVA.
Retrieved [[November 26]], [[2006]], from http://www.pbs.org/wgbh/nova/algae/impact.html</ref> believes that one of the worst cases of a single invasive species causing harm to an ecosystem can be attributed to a seemingly harmless [[jellyfish]]. ''[[Mnemiopsis leidyi]]'', a species of comb jellyfish that inhabits estuaries from the United States to the Valdés peninsula in [[Argentina]] along the [[Atlantic]] coast, has caused notable damage in the [[Black Sea]]. It was first introduced in 1982, and thought to have been transported to the Black Sea in a ship’s ballast water. The population of the jellyfish shot up exponentially and, by 1988, it was wreaking havoc upon the local [[fishing]] industry. "The anchovy catch fell from 204,000 tons in 1984 to 200 tons in 1993; sprat from 24,600 tons in 1984 to 12,000 tons in 1993; horse mackerel from 4,000 tons in 1984 to zero in 1993."<ref name="Meinesz"/> Now that the jellyfish have exhausted the [[zooplankton]], including fish larvae, their numbers have fallen dramatically, yet they continue to maintain a stranglehold on the [[ecosystem]]. Recently the jellyfish have been discovered in the [[Caspian Sea]]. Invasive species can take over once occupied areas, facilitate the spread of new [[diseases]], introduce new [[Genetics|genetic]] material, alter landscapes and jeopardize the ability of native species to obtain food. "On land and in the sea, invasive species are responsible for about 137 billion dollars in lost revenue and management costs in the U.S. each year."<ref name="Panetta">Panetta, L. E. (Chair) (2003). America's living oceans: charting a course for sea change [Electronic Version, CD] Pew Oceans Commission.</ref>
Ballast and [[bilge]] discharge from ships can also spread human [[pathogens]] and other harmful diseases and [[toxins]] potentially causing health issues for humans and marine life alike.<ref name="NRC">National Research Council, Committee on the Ocean's Role in Human Health, Ocean Studies Board, Commission on Geosciences, Environment, and Resources. (1999). ''From monsoons to microbes: understanding the ocean's role in human health''. Washington, D.C.: National Academy Press</ref> Discharges into coastal waters, along with other sources of marine pollution, have the potential to be toxic to marine plants, animals, and [[microorganisms]], causing alterations such as changes in growth, disruption of [[hormone]] cycles, birth defects, suppression of the [[immune system]], and disorders resulting in [[cancer]], [[tumors]], and genetic abnormalities or even death.<ref name="Panetta"/>
===Exhaust emissions===
[[Exhaust]] emissions from ships are considered to be a significant source of [[air pollution]]. “Seagoing vessels are responsible for an estimated 14 percent of emissions of nitrogen from fossil fuels and 16 percent of the emissions of sulfur from petroleum uses into the atmosphere.”<ref name="Panetta"/> In Europe ships make up a large percentage of the sulfur introduced to the air, “…as much sulfur as all the cars, [[lorries]] and factories in Europe put together.”<ref name="Harrabin">Harrabin, R. (2003, June 25). EU faces ship clean-up call. ''BBC News''. Retrieved [[November 1]], [[2006]], from http://news.bbc.co.uk/2/hi/europe/3019686.stm</ref> “By 2010, up to 40% of air pollution over land could come from ships.”<ref name="Harrabin"/> Sulfur in the air creates [[acid rain]] which damages crops and buildings. When inhaled sulfur is known to cause [[respiratory]] problems and increase the risk of a [[myocardial infarction|heart attack]].<ref name="Harrabin"/>
==See also==
{{nautical portal}}
*[[Chartering (shipping)]]
*[[Dynamic positioning]]
*[[Flag State]]<!--This should absolutely be covered within this article itself, not as a see also!-->
*[[Maritime history]]
*[[Maritime law]]
*[[Sailing]]
*[[Sailor]]
*[[Ship burial]]
*[[Ship transport]]
===Model ships===
*[[Ship model basin]]
*[[Ship model]]
*[[Ship replica]]
===Lists===
*[[List of civilian nuclear ships]]
*[[List of famous ships]]
*[[List of fictional ships]]
*[[List of historical ship types]]
*[[List of shipwrecks]]
==Notes==
{{Reflist}}
==References==
*{{cite book
| first = Nathaniel
| last = Bowditch
| authorlink = Nathaniel Bowditch
| title = The American Practical Navigator
| publisher = [[National Imagery and Mapping Agency]]
| url = http://www.irbs.com/bowditch/
| location= Bethesda, MD
| year = 2002
| isbn = 0939837544 }}
* {{cite book
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* {{cite book
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*{{cite web |url=https://exchange.dnv.com/exchange/main.aspx?extool=vessel&subview=summary&vesselid=16864 |title=Knock Nevis |accessdate=2008-04-08 |author=Det Norske Veritas |authorlink=Det Norske Veritas |year=2008 |work=DNV Exchange |publisher=Det Norske Veritas }}
*{{cite encyclopedia
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*{{cite encyclopedia
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*{{cite book |author=Fisheries and Aquacultures Department |editor= |others= |title=The State of World Fisheries and Aquaculture 2006 |origdate= |origyear= |url=http://www.fao.org/docrep/009/a0699e/A0699E00.HTM |accessdate=2008-04-20 |year=2007 |publisher=Food and Agriculture Organization of the United Nations |location=Rome |isbn= |chapter=The Status of the Fishing Fleet|chapterurl=http://www.fao.org/docrep/009/a0699e/A0699E04.htm#4.1.5 }}
*{{cite book |last=George| first=William |title=Stability and Trim for the Ship's Officer |year= 2005|publisher=Cornell Maritime Press |location=Centreville, MD |isbn=978-0-87033-564-8 }}
* {{cite book |last=Hayler |first=William B. |coauthors=Keever, John M. |title=American Merchant Seaman's Manual |year=2003 |publisher= Cornell Maritime Pr |isbn= 0-87033-549-9 }}
*{{cite book |first=Mark| last=Huber |title=Tanker operations: a handbook for the person-in-charge (PIC) |publisher=Cornell Maritime Press |location=Cambridge, MD |year=2001 |isbn=0-87033-528-6 |doi=}}
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*{{cite web |url=http://www.osg.com/uploadedFiles/2222008FleetlistDownload.xls |title=Overseas Shipholding Group Fleet List |accessdate=2008-04-08 |author=Overseas Shipholding Group |date=2008-02-22|publisher=Overseas Shipholding Group }}
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* {{cite book | last = Turpin | first = Edward A. | coauthors = McEwen, William A. | title = Merchant Marine Officers' Handbook | edition = 4th | year = 1980 | month = | publisher =Cornell Maritime Press | location = Centreville, MD | isbn = 0-87038-056-X | chapterurl = }}
*{{cite book |author=United Nations Conference on Trade and Development (UNCTAD) |authorlink=United Nations Conference on Trade and Development |editor= |others= |title=Review of Maritime Transport, 2006 |origdate= |origyear= |url=http://www.unctad.org/en/docs/rmt2006_en.pdf |accessyear= |year=2006 |publisher=United Nations |location=New York and Geneva |isbn= }}
*{{cite book |author=United Nations Conference on Trade and Development (UNCTAD) |authorlink=United Nations Conference on Trade and Development |editor= |others= |title=Review of Maritime Transport, 2007 |origdate= |origyear= |url=http://www.unctad.org/en/docs/rmt2007_en.pdf |accessyear= |year=2007 |publisher=United Nations |location=New York and Geneva |isbn= }}
*{{cite book |last=Stopford|first=Martin|url=http://books.google.com/books?id=_R-YB70kly8C&printsec=frontcover |title=Maritime economics |publisher=Routledge |location=New York |year=1997 |isbn=0-415-15309-3 |doi=}}
==External links==
* [http://www.shipspotting.com/ Photos of Ships]
* [http://ships.galutschek.at/ Video Clips of Ships]
{{Sisterlinks|Ships|wikt=Ship|b=Ship|q=Ships|s=Ships|commons=Category:Ships|n=Ship|v=Ship}}
{{fisheries and fishing|state = collapsed}}
{{ModernMerchantShipTypes}}
{{Sailing Vessels and Rigs}}
{{Warship types of the 19th & 20th centuries}}
[[Category:Ships| ]]
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