Shipwreck of the SS American Star on the shore of Fuerteventura. Construction (1936–1939 America was laid down under the first Maritime Commission contract on 22 August 1938, at Newport News Fuerteventura, a Spanish Island, is one of the Canary Islands, in the Atlantic Ocean off the coast of Africa.

A shipwreck or sunken ship can refer to the remains of a wrecked ship or to the event that caused the wreck, such as the striking of something that causes the ship to sink, the stranding of the ship on rocks, land or shoal, or the destruction of the ship at sea by violent weather. ^[1] There are more than 3 million shipwrecks on the ocean floor, the United Nations estimates. ^[2]

Types of shipwrecks

Historic shipwrecks are attractive to maritime archaeologists because they preserve historical information; for example, studying the wreck of Mary Rose revealed information about seafaring, warfare and life in the 1500s. Maritime archaeology (also known as marine archaeology) is a discipline that studies human interaction with the Sea, lakes and rivers through the study of vessels The Mary Rose was an English Tudor Carrack warship and one of the first to be able to fire a full Broadside of cannons Military wrecks that were caused by a skirmish at sea are studied to find details about the historic event and reveal much about the battle that occurred. Discoveries of treasure ships, often from the period of European colonisation, which sunk in remote places, leaving few living witnesses, such as the Batavia, do occur but only very infrequently. A Treasure ship is the name for a type of large wooden vessel commanded by the Chinese admiral Zheng He on seven voyages in the early fifteenth century Colonisation (also known as Colonization) occurs whenever any one or more species populates a new area Mutiny on the Batavia Departure On 29 October 1628, the newly built Batavia, commissioned by the Dutch East India Company

Some contemporary wrecks, such as the Prestige or Erika, are of interest primarily because of the potential harm to the environment. The Prestige was an Oil tanker whose sinking in 2002 off the Galician coast caused a large Oil spill. Erika was the name of a tanker built in 1975 and last chartered by Total-Fina-Elf. Other contemporary wrecks are scuttled in order to spur reef growth, such as Adolphus Busch and the Ocean Freeze. Wrecks like Adolphus Busch and many historic wrecks such as SS Thistlegorm are of interest to recreational divers who enjoy diving shipwrecks because they are often interesting to explore, provide large habitats for many types of marine life and have an interesting history. Construction The vessel was privately owned and therefore not classified as a Naval vessel. Recreational diving or sport diving is a type of diving that uses SCUBA equipment for the purpose of leisure and enjoyment

Shipwreck in the Saugatuck River mouth in Westport, Connecticut

Very few shipwrecks are famous catastrophes like the wrecks of the Titanic or Estonia. The Saugatuck River is a short river in southwestern Connecticut in the United States, approximately 25 mi (40 km long Westport is a coastal town located on Long Island Sound in Fairfield County, Connecticut, 47 miles north of New York City in the United Construction The Titanic was a White Star Line ocean liner built at the Harland and Wolff shipyard in Belfast, Ireland Construction The ship was originally ordered from Meyer Werft by a Norwegian shipping company led by Parley Augustsen with intended traffic between There are also thousands of wrecks that were not lost at sea but have been abandoned or sunk. These are typically smaller vessels such as fishing vessels. These vessels can provide an interesting recreational dive but are usually of little interest to historians. Scuba diving is swimming underwater, or taking part in another activity while using a Scuba set. They may pose a hazard to navigation and may be removed by port authorities. In Canada and the United States a port authority (less commonly a port district) is a governmental or quasi-governmental Public authority These vessels are sometimes referred to as abandoned or derelicts.

Shipwrecks and the law

Shipwreck law determines important legal questions regarding wrecks, perhaps the most important question being the question of ownership.

MSC Napoli beached off Branscombe

The British Protection of Wrecks Act, enacted to protect historic wrecks, controls access to wrecks such as Cattewater Wreck which can only be visited or investigated under licence. Kyrill While en route from Belgium to Portugal, on January 18 2007, during European windstorm Kyrill, severe gale The Protection of Wrecks Act 1973 (1973 c33 is an Act of Parliament in the United Kingdom which provides protection for designated wrecks. The Cattewater Wreck is a wooden three-masted skeleton-built vessel one of many ships that have wrecked in Cattewater. The British Protection of Military Remains Act 1986 also restricts access to wrecks which are sensitive as war graves. The Protection of Military Remains Act 1986 (1986 c 35 is an Act of Parliament in the United Kingdom which provides protection for the wreckage of military aircraft A war grave is a place where War dead are buried It may contain either a combatant or a civilian The Protection of Military Remains Act in some cases creates a blanket ban on all diving, for others divers may visit provided they do not touch, interfere with or penetrate the wreck. In the United States, shipwrecks in state waters are regulated by the Abandoned Shipwreck Act of 1987. This act is much more lenient in allowing more open access to the shipwrecks.

Following the beaching of the MSC Napoli, as a result of severe damage incurred during European windstorm Kyrill, there was confusion in the press and by the authorities about whether people could be prevented from helping themselves to the flotsam which was washed up on the beaches at Branscombe. Kyrill While en route from Belgium to Portugal, on January 18 2007, during European windstorm Kyrill, severe gale Abstract A European windstorm is a severe Cyclonic Storm that moves across the North Atlantic towards northwestern Branscombe is a village in the East Devon district of the English County of Devon. Many people took advantage of the confusion and helped themselves to the cargo. This included many BMW motorbikes [1] and empty wine casks as well as bags of disposable nappies. ( BMW) (Bavarian Motor Works is an independent German automobile manufacturer founded in 1916 The legal position under the Merchant Shipping Act 1995 is that any such finds and recovery must be reported within 28 days to the Receiver of Wreck. The Receiver of Wreck, a post defined under the Merchant Shipping Act 1995 is an official of the British government whose main task is to process incoming reports The Receiver of Wreck, a post defined under the Merchant Shipping Act 1995 is an official of the British government whose main task is to process incoming reports [2] Failure to do so is an offence under the Merchant Shipping Act and can result in a criminal record for theft by finding. [3] After several days, the police and Receiver of Wreck, in conjunction with the landowner and the contracted salvors, established a cordon to prevent access to the beach. Marine salvage is the process of rescuing a ship its cargo and sometimes the crew from peril [4] A similar situation occurred after the wreck of the MV Cita in 1997. On 26 March, 1997, the 300-ft Merchant vessel MV Cita pierced its hull when running aground on rocks off the south coast of the Isles of Scilly

An important international convention aiming at the protection of underwater cultural heritage (including shipwrecks) is the UNESCO 2001 Convention on the Protection of the Underwater Cultural Heritage. The 2001 UNESCO Convention on the Protection of the Underwater Cultural Heritage represents the international community’s response to the increasing looting and destruction of underwater cultural heritage. It forms part of a group of UNESCO standard setting instruments regarding the domain of cultural heritage, encompassing seven conventions adopted by UNESCO Member States, which constitute a coherent and complementary body guaranteeing a complete protection of all forms of cultural heritage.

The UNESCO 2001 Convention is an international treaty aimed exclusively at the protection of underwater cultural heritage and the facilitation of international cooperation in this regard. It does not change sovereignty rights of States or regulate the ownership of wrecks or submerged ruins.

Salvage of wrecks

Often, attempts are made to salvage recently wrecked ships to recover the whole or part of the ship, its cargo, or its equipment. Marine salvage is the process of rescuing a ship its cargo and sometimes the crew from peril A good example of this was the salvage of the Kaiserliche Marine High Seas Fleet at Scapa Flow in the 1920s. The Kaiserliche Marine or Imperial Navy was the German Navy created by the formation of the German Empire. The High Seas Fleet (Hochseeflotte was the main battle fleet of the Kaiserliche Marine (Imperial German Navy during World War I. Scapa Flow ( Old Norse: Skalpaflói) is a body of water in the Orkney Islands, Scotland, United Kingdom, sheltered by the islands The unauthorized salvage of wrecks is called wrecking. Wrecking is the practice of taking valuables from a Shipwreck which has foundered near or close to shore

As a general rule, civilian shipwrecks are considered fair game for salvage; military wrecks, however, remain under the jurisdiction--and hence, protection--of the government that lost the ship, or that government's successor. Hence, a German U-boat from World War II still technically belongs to the German government, even though the Third Reich is long-defunct. Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe. U-boat is the anglicized version of the German word, itself an abbreviation of Unterseeboot ( undersea boat) and refers World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including Nazi Germany and the Third Reich are the common English names for Germany under the regime of Adolf Hitler and the National Socialist German Workers Many military wrecks are also protected by virtue of their being war graves. A war grave is a place where War dead are buried It may contain either a combatant or a civilian

Older wrecks are often protected from pillaging and looting through national laws protecting cultural heritage. Internationally they may be protected by a State ratifying the Unesco Convention on the Protection of the Underwater Cultural Heritage. The UNESCO Convention on the Protection of the Underwater Cultural Heritage, adopted by the UNESCO General Conference on 2 November 2001 (hereinafter the 2001 In this case pillaging is not allowed.

Causes

Shipwreck , by Claude Joseph Vernet. Claude Joseph Vernet ( August 14, 1714 &ndash December 3, 1789) was a French painter.

Ships are lost for many reasons, including:

• poor design or failure of the ship's equipment or pressure hull
• instability, due to poor design, improperly stowed cargo, cargo that shifts its position or the free surface effect. Naval architecture is an engineering discipline dealing with the design construction and repair of marine vehicles The term light hull is used to describe the outer hull of a submarine which houses the pressure hull providing hydrodynamically efficient shape but not holding pressure difference Cargo (or freight) refers to goods or produce transported generally for Commercial gain by ship, aircraft, train, The free surface effect is one of several mechanisms where a craft can become unstable and roll-over ( Capsize)
• navigation errors and other human errors, leading to collisions (with another ship, rocks, an iceberg, etc. Navigation is the process of reading and controlling the movement of a craft or vehicle from one place to another A collision is an isolated event in which two or more bodies (colliding bodies exert relatively strong forces on each other for a relatively short time An iceberg is a large piece of freshwater Ice that has broken off from a snow-formed Glacier or Ice shelf and is floating in open water ) or running aground
• bad weather
• warfare, piracy, mutiny, or sabotage including: guns, fire, torpedoes, depth charges, mines, bombs and missiles. The weather is a set of all the phenomena occurring in a given Atmosphere at a given Time. War is an international relations Dispute, characterized by organized Violence between National Military units Piracy is Robbery committed at sea or sometimes on shore without a commission from a sovereign Nation (as distinct from Privateering Mutiny is a conspiracy among members of a group of similarly-situated individuals (typically members of the Military; or the Crew of any ship even Sabotage is a deliberate action aimed at weakening an enemy oppressor or employer through subversion obstruction disruption and/or destruction A gun is a particular Weapon that propels Projectiles The projectile is generally fired through a hollow tube known as the gun's barrel. Fire is the heat and light energy released during a Chemical reaction, in particular a combustion reaction. The modern torpedo (historically called an automotive automobile locomotive or fish torpedo is a self-propelled explosive Projectile weapon launched above or below Depth Charge is a character in the Beast Wars: Transformers universe A naval mine is a self-contained Explosive device placed in water to destroy Ships or Submarines Unlike Depth charges mines are deposited A bomb is any of a range of devices that typically rely on the Exothermic Chemical reaction of an Explosive material to produce an extremely A missile (see also pronunciation differences) is a self-propelled explosive Projectile used as a weapon towards a target
• fire
• overloaded with cargo, and exceeded the plimsoll line
• intentional sinking (scuttling)
  • to form an artificial reef
  • use as a target ship for training or testing weapons
  • as a blockship to create an obstacle to close a harbour, river, etc. Fire is the heat and light energy released during a Chemical reaction, in particular a combustion reaction. Waterline refers to an imaginary line marking the level at which Ship or Boat floats in the Water. Scuttling is the act of deliberately sinking a ship by allowing water to flow into the hull. An artificial reef is a man-made underwater structure typically built for the purpose of promoting marine life in areas of generally featureless bottom A target ship is a vessel — typically an obsolete or captured Warship — used for naval Gunnery practice or for weapons testing A blockship is a Ship deliberately sunk to prevent a River, channel, or Canal from being used against enemy ships
  • to prevent a ship from falling into an enemy's hands (e. g. Graf Spee)
  • to destroy a derelict ship that poses a menace to navigation
  • as part of an insurance scam

Design and equipment failure

Poor design allowed the ferry MS Herald of Free Enterprise to put to sea with open roll-on/roll-off bow doors, with tragic consequences. Description Admiral Graf Spee was a Deutschland class cruiser. Insurance fraud or false insurance claims are Insurance claims filed with the intent to defraud an insurance provider Construction In the late 1970s Townsend Thoresen decided to commission the design and construction of three new identical ships for their Dover – Calais route See also Merchant ship Roll-on/roll-off (RORO or ro-ro Ships are ferries designed to carry wheeled Cargo such as

Failure or leaking of the hull is a serious problem that can lead to the loss of buoyancy or the free surface effect and the subsequent sinking of the vessel. A hull is the body of a Ship or Boat. It is a central concept in floating vessels as it provides the Buoyancy that keeps the vessel from sinking In Physics, buoyancy ( BrE IPA: /ˈbɔɪənsi/ is the upward Force on an object produced by the surrounding liquid or gas in which it is The free surface effect is one of several mechanisms where a craft can become unstable and roll-over ( Capsize) Even the hulls of large modern ships have cracked in heavy storms. A storm is any disturbed state of an astronomical body's atmosphere, especially affecting its surface and strongly implying Severe weather. Leaks between the hull planks of wooden vessels is a particular problem.

Failure of pumps can lead to the loss of a potentially salvageable ship with only a minor leak or fire.

Failure of the means of propulsion, such as engines, sails or rigging, can lead to the loss of a ship. An engine is a mechanical device that produces some form of output from a given input A sail is any type of surface intended to generate Thrust by being placed in a Wind &mdashin essence a vertically-oriented Wing. Rigging (from Anglo-Saxon wrigan or wringing, "to clothe" is on Sailboats and Sailing ships the collection of When the ship's movement is determined only by currents or the wind and particularly by storms, a common result is that the ship is unable to avoid natural hazards like rocks, shallow water or tidal races. Wind is the flow of Air or other Gases that compose an Atmosphere (including but not limited to the Earth's) A storm is any disturbed state of an astronomical body's atmosphere, especially affecting its surface and strongly implying Severe weather. In Geology, rock is a naturally occurring aggregate of Minerals and/or Mineraloids The Earth's outer solid layer the ‘ Lithosphere Tidal race (or tidal rapid) is a natural occurrence whereby a fast moving Tide passes through a constriction resulting in the formation of Waves eddies

Instability

Instability is caused by the centre of mass of the ship rising above the metacenter resulting in the ship tipping on its side or capsizing. Mass is a fundamental concept in Physics, roughly corresponding to the Intuitive idea of how much Matter there is in an object The metacentric height (GM is the distance between the center of gravity of a ship and its metacenter The common definition for capsized refers to when a Boat or Ship is tipped over until disabled

This can lead to a sinking if the openings on the upper side of the side are not watertight at the time of the capsise. To remain buoyant, the hull of a vessel must prevent water entering the large air spaces of the vessel (known as downflooding). Clearly for the ship to float, the submerged parts of the hull will be watertight, but the upper parts of the hull must have openings to allow ventilation to compartments, including the engine room, for crew access, and to load and unload cargo.

Bad weather

Ivan Aivazovsky's "The Ninth Wave" painting shows a handful of survivors clinging to the mast of a sunken ship. Ivan Konstantinovich Aivazovsky (Иван Константинович Айвазовский Հովհաննես Այվազովսկի - Hovhannes Aivazovsky July 29,

Poor weather can cause several problems:

• wind
• low visibility
• cold

Wind causes waves which result in other difficulties. Wind is the flow of Air or other Gases that compose an Atmosphere (including but not limited to the Earth's) Ocean surface waves are Surface waves that occur on the Free surface of the Ocean. Waves make navigation difficult and dangerous near shallow water. Also, waves create buoyancy stresses on the structure of a hull. The weight of breaking waves on the fabric of the ship force the crew to reduce speed or even travel in the same direction as the waves to prevent damage. Speed is the rate of motion, or equivalently the rate of change in position often expressed as Distance d traveled per unit of Also, wind stresses the rigging of sailing ships.

The force of the wind pushes ships in the direction of the wind. Vessels with large windage suffer most. Windage is a Force created on an object by Friction when there is relative movement between Air and the object Although powered ships are able to resist the force of the wind, sailing vessels have few defences against strong wind. When strong winds are imminent, sailing vessels typically have several choices:

• try to position themselves so that they cannot be blown into danger
• shelter in a harbour
• anchor, preferably on the leeward side of a landform

Many losses of sailing ships were caused by sailing, with a following wind, so far into a bay that the ship became trapped upwind of a lee shore, being unable to sail into the wind to leave the bay. A harbor or harbour (see spelling differences) or haven, is a place where ships may shelter from the Weather or are stored An anchor is an object often made out of metal that is used to attach a ship to the bottom of a body of water at a specific point Windward is the direction from which the wind is blowing at the time in question Headlands and bays are two related features of the coastal environment The terms lee shore and weather or windward shore are nautical terms used to describe a stretch of Shoreline.

Low visibility caused by fog, mist and heavy rain increase the navigator's problems. Fog is a cloud that is in contact with the ground Stratus clouds are usually the only clouds that touch the ground Mist is a phenomenon of small droplets suspended in Air. It can occur as part of natural Weather or Volcanic activity and is common in cold air above Rain is Liquid precipitation. On Earth it is the condensation of atmospheric Water vapor into drops heavy enough to fall often making it to

Cold can cause metal to become brittle and fail more easily. A build-up of ice can cause instability by accumulating high on the ship, or in severe cases, crush the hull if the ship becomes trapped in a freezing sea. Ice is a Solid phase, usually crystalline, of a Non-metalic substance that is liquid or gas at Room temperature, such as Ammonia

Fire

Fire can cause the loss of ships in many ways. The most obvious way would be the loss of a wooden ship which is burned until watertight integrity is compromised (e. g. Cospatrick). History of the Cospatrick The Cospatrick was a Blackwall Frigate of 1199 tons on dimensions of length between perpendiculars beam depth of hold The detonation of cargo or ammunition can cause the breach of a steel hull. Often a large fire causes a ship to be abandoned and left to drift. Should it run aground beyond economic salvage, it becomes a wreck.

Navigation errors

Many shipwrecks have occurred when the crew of the ship allowed the ship to collide with rocks, reefs, icebergs, or other ships. In nautical terminology a reef is a rock, sandbar, or other feature lying beneath the surface of the water (six fathoms or less at low water An iceberg is a large piece of freshwater Ice that has broken off from a snow-formed Glacier or Ice shelf and is floating in open water Collision has been one of the major causes of shipwreck. Accurate navigation is made more difficult by poor visibility in bad weather. Also, many losses happened before modern navigation aids such as GPS, radar and sonar were available. Basic concept of GPS operation A GPS receiver calculates its position by carefully timing the signals sent by the constellation of GPS Satellites high above the Earth Radar is a system that uses electromagnetic waves to identify the range altitude direction or speed of both moving and fixed objects such as Aircraft, ships Sonar (which started as an Acronym for sound navigation and ranging) is a technique that uses Sound propagation (usually underwater to navigate Until the twentieth century, the most sophisticated navigational tools and techniques available - dead reckoning using the magnetic compass, marine chronometer (to calculate longitude) and ships logbook (which recorded the vessels heading and the speed measured by log) or celestial navigation using marine chronometer and sextant - were sufficiently accurate for journeys across oceans, but these techniques (and in many cases also the charts) lacked the precision to avoid reefs close to shore. Dead reckoning ( DR) is the process of estimating one's current position based upon a previously determined position or fix, and advancing that position based upon A compass, magnetic compass or mariner's compass is a navigational instrument for determining direction relative to the earth's Magnetic poles It consists A marine chronometer is a timekeeper precise enough to be used as a portable Time standard; it can therefore be used to determine Longitude by means of Celestial Longitude (ˈlɒndʒɪˌtjuːd or ˈlɒŋgɪˌtjuːd symbolized by the Greek character Lambda (λ is the east-west Geographic coordinate measurement A Logbook was originally a book for recording readings from the log, and is used to determine the distance a ship traveled within a certain amount of time A chip log, also called common log, ship log or just log, is a Navigation tool used by Mariners to estimate Speed of a vessel Celestial navigation, also known as astronavigation, is a Position fixing technique that was devised to help sailors cross the featureless oceans without having to A marine chronometer is a timekeeper precise enough to be used as a portable Time standard; it can therefore be used to determine Longitude by means of Celestial This article is about the sextant as used for Navigation. For the astronomer's sextant, see Sextant (astronomical. Marine chronometers were as revolutionary in the 19th century as GPS is today. A marine chronometer is a timekeeper precise enough to be used as a portable Time standard; it can therefore be used to determine Longitude by means of Celestial However the cost of these instruments could be prohibitive, sometimes resulting in tragic consequences for ships that were unable to determine their longitude, as in the case of the Arniston. Longitude (ˈlɒndʒɪˌtjuːd or ˈlɒŋgɪˌtjuːd symbolized by the Greek character Lambda (λ is the east-west Geographic coordinate measurement Overview East Indiaman operated under charter or licence to the Honourable East India Company, which held a monopoly granted by Queen Elizabeth I

Even today, when highly accurate navigational equipment is readily available and universally used, there is still scope for error. Using the incorrect horizontal datum for the chart of an area may mislead the navigator, especially as many charts have not been updated to use modern data. This article describes a concept from Surveying and Geodesy. For other meanings see Datum (disambiguation. A chart or graph is a type of Information graphic, that represents tabular numeric data and/or functions. It is also important for the navigator to appreciate that charts may be significantly in error, especially on less frequented coasts. For example, a recent revision of the map of South Georgia in the South Atlantic showed that previous maps were in some places in error by several kilometres. South Georgia and the South Sandwich Islands ( SGSSI) is a British overseas territory in the southern Atlantic Ocean.

Over the centuries, many technological and organisational developments have been used to reduce accidents at sea including:

• International Regulations for Preventing Collisions at Sea
• Pilotage aids including lighthouses and sea marks
• Basic navigation tools such as the magnetic compass, nautical chart, marine chronometer, sextant, log and sounding line
• Advanced navigation tools such as the radio communication, radar navigation, gyrocompass, sonar, hyperbolic Radio navigation and satellite navigation
• Inspection of shipbuilding quality and maintenance of seaworthiness of the ship such as "A1 at Lloyd's"
• Intelligence and better defences to protect the ship from acts of violence, war and piracy
• Use of fireproof/unflamable materials to prevent fires from spreading rapidly, and modern fire-fighting agents such as gases and foams that do not compromise the buoyancy and stability of the vessel as quickly as water. The International Regulations for Preventing Collisions at Sea 1972 ( COLREGS) are published by the International Maritime Organization (IMO and set out the "rules Pilotage is the use of fixed visual references on the ground or sea by means of sight or radar to guide oneself to a destination sometimes with the help of a Map or Nautical A lighthouse is a Tower, building or framework designed to emit light from a system of lamps and lenses or in older times from a fire and used as an A sea mark, also seamark and Navigation mark, is a Pilotage aid which identifies the approximate position of a maritime channel hazard Navigation is the process of reading and controlling the movement of a craft or vehicle from one place to another A compass, magnetic compass or mariner's compass is a navigational instrument for determining direction relative to the earth's Magnetic poles It consists A nautical chart is a graphic representation of a maritime area and adjacent Coastal regions A marine chronometer is a timekeeper precise enough to be used as a portable Time standard; it can therefore be used to determine Longitude by means of Celestial This article is about the sextant as used for Navigation. For the astronomer's sextant, see Sextant (astronomical. A chip log, also called common log, ship log or just log, is a Navigation tool used by Mariners to estimate Speed of a vessel A sounding line or lead line is a length of thin Rope with a Plummet, generally of Lead, at its end Radio is the transmission of signals by Modulation of electromagnetic waves with frequencies below those of visible Light. See also Navigation, Radar radar systems can provide very useful navigation information in a variety of situations A gyrocompass is similar to a Gyroscope. It is a Compass that finds True north by using an (electrically powered fast-spinning wheel and friction Sonar (which started as an Acronym for sound navigation and ranging) is a technique that uses Sound propagation (usually underwater to navigate Radio navigation or radionavigation is the application of Radio frequencies to determining a position on the Earth. Global Navigation Satellite System (GNSS is the standard generic term for satellite navigation systems that provide autonomous geo-spatial positioning with global coverage See also Shipbuilding (song. Shipbuilding is the construction of Ships It normally takes place in a specialized facility known as a In Shipping, the designation A1 is a symbol used to denote quality of construction and material Military intelligence (abbreviated MI int Commonwealth, or intel A fire extinguisher is an Active fire protection device used to extinguish or control small fires often in emergency situations A fire extinguisher is an Active fire protection device used to extinguish or control small fires often in emergency situations
• Built-in devices to delay flooding long enough for rescue ships to retrieve survivors and/or tow the ship to the nearest shipyard for repairs, such as watertight compartments and pumps. Shipyards and dockyards are places which repair and build ships These can be Yachts military Floodability is a characteristic of the construction of a Ship to resist Flooding. For information on Wikipedia project-related discussions see WikipediaVillage pump.

State of preservation

The Vasa is one of the oldest and most well-preserved ships salvaged in the world, due to the low salinity of the Baltic Sea

Many factors determine the state of preservation of a wreck:

• the ship's construction materials
• the wreck becoming covered in sand or silt
• the salinity of the water the wreck is in
• the level of destruction involved in the ship's loss
• whether the components or cargo of the wreck were salvaged
• whether the wreck was demolished to clear a navigable channel
• the depth of water at the wreck site
• the strength of tidal currents or wave action at the wreck site
• the exposure to surface weather conditions at the wreck site
• the presence of marine animals that consume the ship's fabric
• temperature

Construction materials

Exposed wooden components decay quickly. History During the 17th century Sweden went from being a small poor and peripheral northern European kingdom of little influence to one of the major players in continental politics Salinity is the Saltiness or dissolved salt content of a body of Water. Cargo (or freight) refers to goods or produce transported generally for Commercial gain by ship, aircraft, train, Marine salvage is the process of rescuing a ship its cargo and sometimes the crew from peril Characteristics A tide is a repeated cycle of sea level changes in the following stages Over several hours the water rises or advances up a beach in the flood Ocean surface waves are Surface waves that occur on the Free surface of the Ocean. Wood is hard fibrous lignified structural tissue produced as secondary Xylem in the stems of Woody plants notably trees but also shrubs Often the only wooden parts of ships that remain after a century are those that were buried in silt or sand soon after the sinking. A century (from the Latin centum, meaning one hundred is One hundred consecutive Years Centuries are numbered ordinally (e Silt is Soil or rock derived Granular material of a Grain size between sand and clay Sand is a naturally occurring Granular material composed of finely divided rock and Mineral particles An example of this is the Mary Rose. The Mary Rose was an English Tudor Carrack warship and one of the first to be able to fire a full Broadside of cannons

Steel and iron, depending on their thickness, may retain the ship's structure for decades. Steel is an Alloy consisting mostly of Iron, with a Carbon content between 0 Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 As corrosion takes place, sometimes helped by tides and weather, the structure collapses. Corrosion means the breaking down of essential properties in a material due to Chemical reactions with its surroundings Thick ferrous objects like cannons, steam boilers or the pressure vessel of a submarine often survive well underwater in spite of corrosion. | NOTE Throughout this article "cannon" is used as BOTH the || singular and plural Uses A Steam engine uses the expansion of steam in order to drive a Piston or Turbine to perform Mechanical work. A boiler is a closed vessel in which Water or other Fluid is heated A pressure vessel is a closed container designed to hold gases or liquids at a Pressure different from the ambient Pressure. A submarine is a Watercraft that can operate independently below water as distinct from a Submersible that has only limited underwater capability

Propellers, condensers, hinges and port holes were often made from non-ferrous metals such as brass and phosphor bronze, which do not corrode easily. A propeller is essentially a type of fan which transmits power by converting Rotational motion into Thrust for propulsion of a vehicle such as an A hinge is a type of bearing that connects two solid objects typically allowing only a limited angle of Rotation between them Brass is any Alloy of Copper and Zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties Phosphor bronze is an Alloy of Copper with 35 to 10% of Tin and a significant Phosphorus content of up to 1%

Salinity of water

Shipwrecks typically decay rapidly when in sea water; shipwrecks in some fresh water lakes, such as the Great Lakes of North America, have remained intact with little degradation. Seawater is Water from a Sea or Ocean. On average seawater in the world's oceans has a Salinity of about 3 Freshwater is a word that refers to bodies of water such as Ponds lakes rivers and streams containing low concentrations of dissolved Salts and other Total dissolved The Laurentian Great Lakes are a chain of freshwater lakes located in eastern North America, on the Canada–United States border. There are two reasons for this:

• Iron-based metals corrode much more quickly in sea water due to the dissolved salt present; the sodium and chloride ions chemically accelerate the process of metal oxidation which, in the case of ferrous metals, leads to rust. Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Corrosion means the breaking down of essential properties in a material due to Chemical reactions with its surroundings Salt is a Dietary mineral composed primarily of Sodium chloride that is essential for Animal life but toxic to most land plants An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge Rust is a general term for a series of Iron oxides, usually red oxides formed by the reaction of Iron with Oxygen in the presence of water or air
• Bacteria found in sea water cause the wood on ships to rot more quickly than in fresh water. The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have Wood is hard fibrous lignified structural tissue produced as secondary Xylem in the stems of Woody plants notably trees but also shrubs

In some sea areas, most notably in Gulf of Bothnia and Gulf of Finland, salinity is very low, and centuries-old wrecks have been preserved in reasonable condition. The Gulf of Bothnia (Pohjanlahti Bottniska viken ie Bottenviken + Bottenhavet is the northernmost arm of the Baltic Sea. The Gulf of Finland ( Finnish: Suomenlahti, Russian: Финский залив, Finskiy zaliv, Swedish: Finska viken

Loss, salvage and demolition

HMS Antelope's magazine explodes

An important factor in the condition of the wreck is the level of destruction at the time of the loss or shortly afterwards due to the nature of the loss, salvage or later demolition. See also firearms magazine for an explanation of the magazines used to load man-portable weapons

Examples of severe destruction at the time of loss are:

• being blown onto a beach, reef or rocks during a storm
• collision with another ship
• a catastrophic explosion (e. g. HMS Hood, HMS Sheffield (D80) )
• a fire that burns for a long time before the ships sinks

After the loss the owners of the ship may attempt to salvage valuable parts of the ship or its cargo - this operation can cause damage. History Construction Construction of Hood began at the John Brown & Company shipyards in Clydebank, Scotland, on 1 September The sinking of HMS Sheffield British version At approximately 10 A Marine salvage is the process of rescuing a ship its cargo and sometimes the crew from peril

Shipwrecks in shallow water near busy shipping lanes are often demolished to reduce the danger to other vessels.

Depth, tide and weather

Wrecks are slowly broken up by exposure to wave action, the weather and the tides. Ocean surface waves are Surface waves that occur on the Free surface of the Ocean. Characteristics A tide is a repeated cycle of sea level changes in the following stages Over several hours the water rises or advances up a beach in the flood Additionally, wrecks in deeper water suffer more degradation due to higher levels of water pressure.

Temperature

Extreme cold (such as in a glacial-fed lake) can slow degradation of organic ship materials. "Glacial" and "Glaciation" redirect here For the geological periods see Glacial period.

See also

• List of shipwrecks
• Wreck diving
• Underwater archaeologists

References

• Hans Blumenberg, Shipwreck with Spectator: Paradigm of a Metaphor for Existence (Cambridge, Mass. : MIT Press, 1997)

External links

• UNESCO page on underwater cultural heritage
• UNESCO 2001 Convention on the Protection of the Underwater Cultural Heritage
• Ethics in Underwater Archaeology (Capitalism versus Socialism in Underwater Archaeology) by E. Lee Spence
• Sea Research Society (shipwrecks, cannon, and underwater archaeology)
• More than 3 million shipwrecks rest beneath the world's waters
• Lighthouse Archaeological Maritime Program (LAMP), St. Augustine, Florida
• Database of 100,000+ North American shipwrecks from 25 years of documenting wrecks
• Database of 10,000 submerged wrecks and obstructions in the coastal waters of the United States
• National Underwater and Marine Agency
• Florida Shipwrecks: 300 years of Maritime History, a National Park Service Discover Our Shared Heritage Travel Itinerary
• Flinders University Maritime Archaeology Program
• Maritimequest Shipwreck Database (Downloadable Excel file)
• Straits of Mackinac Shipwreck Preserve
• Shipwrecks and Smuggling - a learning resource from the British Library archives
• Shipwrecks UK, providing context, thematic information and detail for more than 45,000 shipwrecks in the seas surrounding Britain and Ireland, including revealing maps.
• Documents relating to shipwrecks off the Welsh coast