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A ship is a large watercraft designed for travel across the surface of a body of water, carrying cargo or , or in support of specialized tasks such as Naval warfare, oceanography and fishing. Ships are generally distinguished from , based on size, shape, load capacity and purpose. Ships have supported exploration, Global trade, Naval warfare, Human migration, colonization, and science. Ship transport is responsible for the largest portion of world commerce.
The word ship has meant, depending on era and context, either simply a large vessel or specifically a full-rigged ship with three or more masts, each of which is .
The earliest historical evidence of boats is found in Egypt during the 4th millennium BC. Britannica – History of ships In 2024, ships had a global cargo capacity of 2.4 billion tons, with the three largest classes being ships carrying dry bulk (43%), oil tankers (28%) and container ships (14%).
Starting around the middle of the 18th century, sailing vessels started to be categorised by their type of rig. (Previously they were described by their hull typefor example pink, cat.) Alongside the other rig types such as schooner and brig, the term "ship" referred to the rig type. In this sense, a ship is a vessel with three or more masts, all of which are Square rig. For clarity, this may be referred to as a full-rigged ship or a vessel may be described as "ship-rigged". Alongside this rig-specific usage, "ship" continued to have the more general meaning of a large sea-going vessel. Often the meaning can only be determined by the context. (2025). 9789004424081, Brill. ISBN 9789004424081 (2025). 9780851741765, Brown, Son and Ferguson. ISBN 9780851741765
Some large vessels are traditionally called boats, notably . Others include lake freighter, , and , which may be designed for operation on inland or protected coastal waters.
In most maritime traditions ships have individual names, and modern ships may belong to a ship class often named after its first ship.
In many documents the ship name is introduced with a ship prefix being an abbreviation of the ship class, for example "MS" (motor ship) or "SV" (sailing vessel), making it easier to distinguish a ship name from other individual names in a text.
"Ship" (along with "nation") is an English word that has retained a female grammatical gender in some usages, which allows it sometimes to be referred to as a "she" without being of female Gender.
Examples of the consequences of this include the large grain trade in the Mediterranean during the classical period. Cities such as Rome were totally reliant on the delivery by sailing and human powered (oars) ships of the large amounts of grain needed. It has been estimated that it cost less for a sailing ship of the Roman Empire to carry grain the length of the Mediterranean than to move the same amount 15 miles by road. Rome consumed about 150,000 tons of Egyptian grain each year over the first three centuries AD. (1995). 9780801851308, Johns Hopkins University Press. ISBN 9780801851308 (2025). 9780817319397, The University of Alabama Press. ISBN 9780817319397
Until recently, it was generally the case that ships were the most advanced representations of the technology available to the societies that produced them.
Austronesian peoples originated in what is now Taiwan. From here, they took part in the Austronesian Expansion. Their distinctive maritime technology was integral to this movement and included and outrigger ship. It has been suggested that they had sails some time before 2000 BC. (2025). 9780731521326 ISBN 9780731521326 Their crab claw sails enabled them to sail for vast distances in open ocean. From Taiwan, they rapidly colonized the islands of Maritime Southeast Asia, then sailed further onwards to Micronesia, Island Melanesia, Polynesia, and Madagascar, eventually colonizing a territory spanning half the globe.
Austronesian sails were made from woven leaves, usually from Pandanus plants. These were complemented by paddlers, who usually positioned themselves on platforms on the in the larger boats. Austronesian ships ranged in complexity from simple with outriggers or lashed together to large edge-pegged plank-built boats built around a keel made from a dugout canoe. Their designs were unique, evolving from ancient rafts to the characteristic double-hulled, single-outrigger, and double-outrigger designs of Austronesian ships.
In the 2nd century AD, people from the Indonesian archipelago already made large ships measuring over 50 m long and standing 4–7 m out of the water. They could carry 600–1000 people and 250–1000 ton cargo. These ships were known as kunlun bo or k'unlun po (崑崙舶, lit. "ship of the Kunlun people") by the Chinese, and kolandiaphonta by the Greeks. They had 4–7 masts and were able to sail against the wind due to the usage of . These ships may have reached as far as Ghana. In the 11th century, a new type of ship called djong or jong was recorded in Java and Bali. (2025). 9783940344120 ISBN 9783940344120 This type of ship was built using wooden dowels and treenails, unlike the kunlun bo which used vegetal fibres for lashings.
In China, miniature models of ships that feature steering oars have been dated to the Warring States period (c. 475–221 BC). By the Han dynasty, a well kept naval fleet was an integral part of the military. Centre-line rudders, mounted at the stern, started to appear on Chinese ship models starting in the 1st century AD. However, these early Chinese ships were fluvial (riverine), and were not seaworthy. (2025). 9789292234140, UNESCO Bangkok, Asia and Pacific Regional Bureau for Education. . ISBN 9789292234140 The Chinese only acquired sea-going ship technologies in the 10th-century AD Song dynasty after contact with Southeast Asian k'un-lun po trading ships, leading to the development of the junks.
The were perfectly at ease building sailboats. A remarkable example of their shipbuilding skills was the Khufu ship, a vessel in length entombed at the foot of the Great Pyramid of Giza around 2500 BC and found intact in 1954.
The oldest discovered sea faring hulled boat is the Late Bronze Age Uluburun shipwreck off the coast of Turkey, dating back to 1300 BC.
By 1200 BC, the were building large merchant ships. In world maritime history, declares Richard Woodman, they are recognized as "the first true seafarers, founding the art of pilotage, cabotage, and navigation" and the architects of "the first true ship, built of planks, capable of carrying a deadweight cargo and being sailed and steered."
The empire of Majapahit used large ships called jong, built in northern Java, for transporting troops overseas. The jongs were transport ships which could carry 100–2000 tons of cargo and 50–1000 people, 28.99–88.56 meter in length. The exact number of jong fielded by Majapahit is unknown, but the largest number of jong deployed in an expedition is about 400 jongs, when Majapahit attacked Pasai, in 1350.Hill (June 1960). "". Journal of the Malaysian Branch of the Royal Asiatic Society. 33: p. 98 and 157: "Then he directed them to make ready all the equipment and munitions of war needed for an attack on the land of Pasai – about four hundred of the largest junks, and also many barges (malangbang) and galleys." See also Nugroho (2011). p. 270 and 286, quoting Hikayat Raja-Raja Pasai, 3: 98: " Sa-telah itu, maka di-suroh baginda musta'idkan segala kelengkapan dan segala alat senjata peperangan akan mendatangi negeri Pasai itu, sa-kira-kira empat ratus jong yang besar-besar dan lain daripada itu banyak lagi daripada malangbang dan kelulus." (After that, he is tasked by His Majesty to ready all the equipment and all weapons of war to come to that country of Pasai, about four hundred large jongs and other than that much more of malangbang and kelulus.)
An exception to clinker construction in the Northern European tradition is the bottom planking of the cog. Here, the hull planks are not joined to each other and are laid flush (not overlapped). They are held together by fastening to the frames but this is done after the shaping and fitting of these planks. Therefore, this is another case of a "shell first" construction technique.
These Northern European ships were rigged with a single mast setting a Square rig. They were steered by rudders hung on the .
In contrast, the ship-building tradition of the Mediterranean was of carvel constructionthe fitting of the hull planking to the frames of the hull. Depending on the precise detail of this method, it may be characterised as either "frame first" or "frame-led". In either variant, during construction, the hull shape is determined by the frames, not the planking. The hull planks are not fastened to each other, only to the frames.
These Mediterranean ships were rigged with lateen sails on one or more masts (depending on the size of the vessel) and were steered with a side rudder. They are often referred to as "round ships".
Crucially, the Mediterranean and Northern European traditions merged. Cogs are known to have travelled to the Mediterranean in the 12th and 13th centuries. Some aspects of their designs were being copied by Mediterranean ship-builders early in the 14th century. Iconography shows square sails being used on the mainmast but a lateen on the mizzen, and a sternpost hung rudder replacing the side rudder. The name for this type of vessel was "coche" or, for a larger example, "carrack". Some of these new Mediterranean types travelled to Northern European waters and, in the first two decades of the 15th century, a few were captured by the English, two of which had previously been under charter to the French. The two-masted rig started to be copied immediately, but at this stage on a clinker hull. The adoption of carvel hulls had to wait until sufficient shipwrights with appropriate skills could be hired, but by late in the 1430s, there were instances of carvel ships being built in Northern Europe, and in increasing numbers over the rest of the century.
This hybridisation of Mediterranean and Northern European ship types created the full-rigged ship, a three-masted vessel with a square-rigged foremast and mainmast and a lateen sail on the mizzen. This provided most of the ships used in the Age of Discovery, being able to carry sufficient stores for a long voyage and with a rig suited to the open ocean. Over the next four hundred years, steady evolution and development, from the starting point of the carrack, gave types such as the galleon, fluit, East Indiaman, ordinary cargo ships, warships, and many more, all based on this three-masted square-rigged type.
The transition from clinker to carvel construction facilitated the use of artillery at sea since the internal framing of the hull could be made strong enough to accommodate the weight of guns. It was easier to fit gunports in a carvel hull. As vessels became larger and the demand for ship-building timber affected the size of trees available, clinker construction became limited by the difficulty of finding large enough logs from which to cleave planks. Nonetheless, some clinker vessels approached the size of contemporary carracks. Before the adoption of carvel construction, the increasing size of clinker-built vessels necessitated greater amounts of internal framing of their hulls for strengthsomething that somewhat lessened the conceptual change to the new technique.
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, self-financed by the commercial benefits of exploration.
During the first half of the 18th century, the French Navy began to develop a new type of vessel known as a ship of the line, featuring seventy-four guns. This type of ship became the backbone of all European fighting fleets. These ships were long and their construction required 2,800 oak trees and of rope; they carried a crew of about 800 sailors and soldiers. During the 19th century the Royal Navy enforced a ban on the slave trade, acted to suppress piracy, and continued to map the world. Ships and their owners grew with the 19th century Industrial Revolution across Europe and North America, leading to increased numbers of oceangoing ships, as well as other coastal and canal based vessels.
Through more than half of the 19th century and into the early years of the 20th century, steamship coexisted with sailing vessels. Initially, steam was only viable on shorter routes, typically transporting passengers who could afford higher fares, and mail. Steam went through many developmental steps that gave greater fuel efficiency, thereby increasingly making steamships commercially competitive with sail. Screw propulsion worked better than paddle wheels, but relied, among other things, on the invention of an effective Stuffing box for the propeller shaft. Higher boiler pressures of powering compound engines, were introduced in 1865, making long-distance steam cargo vessels commercially viable on the route from England to Chinaeven before the opening of the Suez Canal in 1869. Within a few years, steam had replaced many of the sailing ships that had served this route. Even greater fuel efficiency was obtained with triple-expansion steam enginesbut this had to wait for higher quality steel to be available to make boilers running at in SS Aberdeen (1881). By this point virtually all routes could be served competitively by steamships. Sail continued with some cargoes, where low costs were more important to the shipper than a predictable and rapid journey time. (1993). 9780851775654, Conway Maritime Press. ISBN 9780851775654
The Second Industrial Revolution in particular led to new mechanical methods of propulsion, and the ability to construct ships from metal triggered an explosion in ship design. These led to the development of long-distance commercial ships and , as well as technological changes including the Marine steam engine, screw propellers, triple expansion engines and others.Ross Munro-Smith (2025). 9781856098960, Institute of Maritime Engineering, Science and Technology. ISBN 9781856098960 Factors included the quest for more efficient ships, the end of long running and wasteful maritime conflicts, and the increased financial capacity of industrial powers created more specialized ships and other maritime vessels. Ship types built for entirely new functions that appeared by the 20th century included Research vessel, offshore support vessels (OSVs), Floating production storage and offloading (FPSOs), Cable layer, drill ships and . (2025). 9781856096324, Witherby Publishing Group. ISBN 9781856096324
The late 20th century saw changes to ships that included the decline of ocean liners as air travel increased. The rise of container ships from the 1960s onwards dramatically changed the nature of commercial merchant shipping, as containerization led to larger ship sizes, dedicated container routes and the decline of general cargo vessels as well as tramp steaming. The late 20th century also saw a rise in cruise ships for tourism around the world. (2025). 9781780646084, CABI. ISBN 9781780646084
In 2008, there were 1,240 operating in the world, not counting small vessels such as . 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 20th century saw many naval engagements during the two , 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.
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. can be found in most seaside villages in the world. As of 2004, the United Nations Food and Agriculture Organization estimated 4 million fishing vessels were operating worldwide. The same study estimated that the world's 29 million fishermenUNFAO 2005, p. 6. caught of fish and shellfish that year.UNFAO 2005, p. 9.
In 2023, the number of ships globally grew by 3.4%. In 2024, new ships are increasingly being built with alternative fuel capability to increase sustainability and reduce carbon emissions. Alternative ship fuels include LNG, LPG, methanol, biofuel, ammonia and hydrogen among others.
As of 2024, wind power for ships had received renewed interest for its potential to mitigate greenhouse gas emissions.
Since the freshwater lakes are less corrosive to ships than the Seawater of the oceans, lakers tend to last much longer than ocean freighters. Lakers older than 50 years are not unusual, and as of 2005, all were over 20 years of age.Office of Data and Economic Analysis, 2006, p. 2.
, built in 1906 as William P Snyder, was the oldest laker still working on the Lakes until its conversion into a barge starting in 2013. Similarly, E.M. Ford, built in 1898 as Presque Isle, was sailing the lakes 98 years later in 1996. As of 2007 E.M. Ford was still afloat as a stationary transfer vessel at a riverside cement silo in Saginaw, Michigan.
Modern commercial vessels are typically powered by a single propeller driven by a diesel engine or, less usually, gas turbine engine., but until the mid-19th century they were predominantly square sail rigged. The fastest vessels may use . Most commercial vessels such as container ships, have full hull-forms (higher Block coefficients) to maximize cargo capacity. (2025). 9781856096324, Witherby Publishing Group. ISBN 9781856096324 Merchant ships and fishing vessels are usually made of steel, although aluminum can be used on faster craft, and fiberglass or wood on smaller vessels. (2025). 9781856096324, Witherby Publishing Group. ISBN 9781856096324 Commercial vessels generally have a crew headed by a sea captain, with and on larger vessels. Special-purpose vessels often have specialized crew if necessary, for example scientists aboard .
Fishing boats are generally small, often little more than but up to for a large tuna or whaling ship. Aboard a fish processing vessel, the catch can be made ready for market and sold more quickly once the ship makes port. Special purpose vessels have special gear. For example, trawlers have winches and arms, stern-trawlers have a rear ramp, and tuna seiners have skiffs. In 2004, of fish were caught in the marine capture fishery.UNFAO, 2007, p. 11. Anchoveta represented the largest single catch at . That year, the top ten marine capture species also included Alaska pollock, Blue whiting, Skipjack tuna, Atlantic herring, Chub mackerel, Anchovy, Trachurus, Largehead hairtail, and Yellowfin tuna. Other species including salmon, shrimp, lobster, , squid and crab, are also commercially fished. Modern commercial fishermen use many methods. One is fishing by Fishing net, such as Seine fishing, beach seine, lift nets, , or entangling nets. Another is , including Bottom trawling. Fish hook and lines are used in methods like long-line fishing and hand-line fishing. Another method is the use of fishing trap.
Cargo ships transport dry and liquid cargo. Dry cargo can be transported in bulk by , packed directly onto a general cargo ship in break-bulk, packed in intermodal containers as aboard a container ship, or driven aboard as in roll-on roll-off ships. Liquid cargo is generally carried in bulk aboard tankers, such as which may include both crude and finished products of oil, which may also carry vegetable oils other than chemicals and , although smaller shipments may be carried on container ships in .
range in size from small river ferries to very large . This type of vessel includes ferry, which move passengers and vehicles on short trips; , which carry passengers from one place to another; and , which carry passengers on voyages undertaken for pleasure, visiting several places and with leisure activities on board, often returning them to the port of embarkation. and ferry boat 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.
are a subset of commercial vessels, but generally small in size and often subject to different regulations and classification. They can be categorized by several criteria: architecture, the type of fish they catch, the fishing method used, geographical origin, and technical features such as rigging. As of 2004, the world's fishing fleet consisted of some 4 million vessels.UNFAO, 2007, p. 25. Of these, 1.3 million were decked vessels with enclosed areas and the rest were open vessels. Most decked vessels were mechanized, but two-thirds of the open vessels were traditional craft propelled by sails and oars. More than 60% of all existing large fishing vessels were built in Japan, Peru, the Russian Federation, Spain or the United States of America.UNFAO, 2007, p. 28.
The weather ship crews were normally at sea for three weeks at a time, returning to port for 10-day stretches. Weather ship observations proved to be helpful in wind and wave studies, as they did not avoid weather systems like other ships tended to for safety reasons. They were also helpful in monitoring storms at sea, such as . The removal of a weather ship became a negative factor in forecasts leading up to the Great Storm of 1987. Beginning in the 1970s, their role became largely superseded by due to the ships' significant cost. The agreement of the use of weather ships by the international community ended in 1990. The last weather ship was Polarfront, known as weather station M ("Mike"), which was put out of operation on 1 January 2010. Weather observations from ships continue from a fleet of voluntary merchant vessels in routine commercial operation.
Modern warships are generally divided into seven main categories: , , , , , and amphibious warfare ships. The distinctions among cruisers, destroyers, frigates, and corvettes are not codified; the same vessel may be described differently in different navies. were used during the Second World War and occasionally since then (the last battleships were removed from the U.S. Naval Vessel Register in March 2006), but were made obsolete by the use of carrier-borne aircraft and .With the addition of corvettes, this is the categorization used at
Most military submarines are either or ballistic missile submarines. Until the end of World War II 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, submarines also became able to effectively hunt each other. The development of submarine-launched nuclear and cruise missiles gave submarines a substantial and long-ranged ability to attack both land and sea targets with a variety of weapons ranging from to .
Most Navy also include many types of support and auxiliary vessel, such as , , offshore patrol vessels, replenishment ships, and which are designated healthcare facilities. Hospital Ship (definition via WordNet, Princeton University)
Fast combat vessels such as cruisers and destroyers usually have fine hulls to maximize speed and maneuverability.Cutler, 1999, p. 224. They also usually have advanced marine electronics and communication systems, as well as weapons.
Hulls have several elements. The 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. Common hull appendages include for propulsion, for steering, and 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.
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 materials are often found in sailboats and pleasure craft. Some ships have been made with Concrete ship.
Mechanical propulsion systems generally consist of a motor or engine turning a propeller, or less frequently, an impeller or wave propulsion fins. were first used for this purpose, but have mostly been replaced by two-stroke or four-stroke diesel engines, outboard motors, and gas turbine engines on faster ships. Nuclear reactors producing steam are used to propel and , and there have been attempts to use them to power commercial vessels (see NS Savannah).
In addition to traditional fixed and controllable pitch propellers there are many specialized variations, such as contra-rotating and nozzle-style propellers. Most vessels have a single propeller, but some large vessels may have up to four propellers supplemented with bow thruster for maneuvring at ports. The propeller is connected to the main engine via a propeller shaft and, in case of medium- and high-speed engines, a reduction gearbox. Some modern vessels have a diesel–electric powertrain in which the propeller is turned by an electric motor powered by the ship's generators.
As environmental sustainability becomes a paramount concern, the maritime industry is exploring cleaner propulsion technologies. Alternatives like LPG (Liquefied Petroleum Gas), ammonia, and hydrogen are emerging as viable options. LPG is already utilized as fuel for long-distance shipping, offering a cleaner option with a lower carbon footprint. Meanwhile, hydrogen and ammonia technologies are in development stages for long-haul applications, promising even more significant reductions in emissions and a step closer to achieving carbon-neutral shipping.
Some propulsion systems are inherently steering systems. Examples include the outboard motor, the bow thruster, and the azimuth thruster.
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.
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 increase in resistance with increasing speed.
This hull speed is found by the formula:
or, in metric system units:
where L is the length of the waterline in feet or meters.
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.
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 waves 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 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.
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.
As environmental laws are becoming more strict, ship designers need to create their design in such a way that the ship, when it nears its end-of-term, can be Ship breaking or Ship disposal easily and that waste is reduced to a minimum.
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 , by the laying of the keel. This is done in a drydock 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 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 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 because of the cost of embedded electronics: a costs around $2 billion, and an aircraft carrier goes for about $3.5 billion.
In 2023, the majority of the world's ships (95% of global output) were built in just three countries: China, South Korea and Japan.
Most ships, however, require trips to special facilities such as a drydock at regular intervals. Tasks often done at drydock include removing biological growths on the hull, sandblasting and repainting the hull, and replacing sacrificial anodes 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.
Some vessels that sustain major damage at sea may be repaired at a facility equipped for major repairs, such as a shipyard. Ships may also be converted for a new purpose: are often converted into floating production storage and offloading units.
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 at sea or Ship breaking by ship breaking. Ships can also be used as museum ships, or expended to construct breakwaters or .
Many ships do not make it to the scrapyard, and are lost in fires, collisions, ship grounding, or sinking at sea. The Allies lost some 5,150 ships during World War II.
In Britain until Samuel Plimsoll's 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. Plimsoll, a Member of Parliament, realised the problem and engaged some 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 "Plimsoll mark", "freeboard mark" or "load line mark", 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. These are called the "load lines" in the marine industry.
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 of crude oil, or . This is more than six times the amount spilled in the widely known Exxon Valdez incident. In this spill, the ship ran aground and dumped of oil into the ocean in March 1989. Despite efforts of scientists, managers, and volunteers, over 400,000 seabirds, about 1,000 sea otters, and immense numbers of fish were killed.
The International Tanker Owners Pollution Federation has researched 9,351 accidental spills since 1974. According to this study, most spills result from routine operations such as loading cargo, discharging cargo, and taking on fuel oil. 91% of the operational oil spills were small, resulting in less than 7 tons per spill. Spills resulting from accidents like collisions, groundings, hull failures, and explosions are much larger, with 84% of these involving losses of over 700 tons.
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 by 2015. Following the sinkings of Erika (1999) and 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".
One of the problems with ballast water transfer is the transport of harmful organisms. Meinesz believes that one of the worst cases of a single invasive species causing harm to an ecosystem can be attributed to a seemingly harmless organism . Mnemiopsis leidyi, a species of comb jelly 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 comb jelly shot up exponentially and, by 1988, it was wreaking havoc upon the local fishing industry. "The anchovy catch fell from in 1984 to in 1993; sprat from in 1984 to in 1993; horse mackerel from in 1984 to zero in 1993." Now that the comb jellies have exhausted the zooplankton, including fish larvae, their numbers have fallen dramatically, yet they continue to maintain a stranglehold on the ecosystem. Recently the comb jellies have been discovered in the Caspian Sea. Invasive species can take over once occupied areas, facilitate the spread of new diseases, introduce new Genetics 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."
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.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, DC: National Academy Press 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.
In addition to steel and other useful materials, however, ships (particularly older vessels) can contain many substances that are banned or considered dangerous in developed countries. Asbestos and polychlorinated biphenyls (PCBs) are typical examples. Asbestos was used heavily in ship construction until it was finally banned in most of the developed world in the mid-1980s. Currently, the costs associated with removing asbestos, along with the potentially expensive insurance and health risks, have meant that ship-breaking in most developed countries is no longer economically viable. Removing the metal for scrap can potentially cost more than the scrap value of the metal itself. In most of the developing world, however, shipyards can operate without the risk of Personal injury or workers' health claims, meaning many of these shipyards may operate with high health risks. Furthermore, workers are paid very low rates with no overtime or other allowances. Protective equipment is sometimes absent or inadequate. Dangerous vapors and fumes from burning materials can be inhaled, and dusty asbestos-laden areas around such breakdown locations are commonplace.
Aside from the health of the yard workers, in recent years, ship breaking has also become an issue of major environmentalism. Many developing nations, in which ship breaking yards are located, have lax or no environmental law, enabling large quantities of highly toxic materials to escape into the environment and causing serious health problems among ship breakers, the local population and wildlife. Environmental campaign groups such as Greenpeace have made the issue a high priority for their campaigns.
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