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Oil tankers, also known as petroleum tankers, or tankers are ships designed for the bulk transport of oil. There are two basic types of oil tanker: the crude tanker and the product tanker.^[1] Crude tankers move large quantities of unrefined crude oil from its point of extraction to refineries.^[1] Product tankers, generally much smaller, are designed to move petrochemicals from refineries to points near consuming markets.

Some specialized types of oil tankers have evolved. One of these is the naval oiler, a tanker which can fuel a moving vessel. Another specialized design is the Ore-bulk-oil carrier which combines aspects of tankers and dry bulk carriers.

Oil tankers are often classified by their size as well as their occupation. The size classes range from inland or coastal tankers of a few thousand tons to the mammoth supertankers of 650,000 tons.

Oil tankers have been involved in a number of damaging and high-profile oil spills. As a result, they are subject to stringent design and operational regulations.

History

The *Falls of Clyde* is the oldest surviving American tanker and the world's only surviving sail-driven oil tanker.^[2]

The technology of oil transportation has evolved alongside the oil industry. Although man's use of oil reaches to prehistory, the first modern commercial exploitation dates back to James Young's manufacture of parafin in 1850.^[3] In these early days, oil from Upper Burma was moved in earthenware vessels to the river bank where it was then poured into boat holds.^[4] In the 1850s, the Pennsylvania oil fields became a major supplier of oil, and a center of innovation.^[4] Break-bulk boats and barges were originally used to transport Pennsylvania oil in 40-gallon wooden barrels.^[4] The idea of moving bulk oil in specially-constructed tanks evolved quickly on America's railways, with modern-style cylindrical tank-cars emerging in 1871.^[4]

In 1863, two sail-driven tankers were built on the River Tyne.^[5] These were followed by the first oil-tank steamer, named the Vaderland.^[5] The first successful oil tanker was the Zoroaster, was designed by Ludwig Nobel (brother of Alfred Nobel) and built in 1877.^[5] This vessel had a displacement of 250 tons, with a length overall of 184 feet, a beam of 27 feet, and a draft of nine feet.

The Zoroaster plied the Caspian Sea from the Apsheron Peninsula, near Baku, in what was then the Russian Empire. Earlier designs suffered greatly from safety problems due to the free surface effect: as the tanker heaved in the sea, the oil would move more quickly than the water, causing ships to capsize. Nobel's tanker had proved itself in the unforgiving waters of the Atlantic ocean and his basic concept revolutionised the transport of oil.

In 1903, the Nobel brothers built two oil tankers which ran on internal combustion engines, as opposed to the older steam engines.^[5] The Vandale and Sarmat were each capable of carrying 750 tons of refined oil and powered by 360 horsepower diesel motors.^[6] This same firm soon went on to make much larger oil tankers, such as the Emanuel Nobel and Karl Hagelin, 4,600-ton kerosene tankers with 1,200 horsepower engines.^[7]

Size categories

Photo	Class^[8]	Tonnage (dwt)	Typical load (bbl)
Oil Tanker Size Categories
The Fredericksburg was a coastal oil tanker of 40,000 dwt.	Seawaymax	10,000-60,000
The Fredericksburg was a coastal oil tanker of 40,000 dwt.	Panamax	60,000-80,000
The Aframax tanker Gerd Knutsen at the wharf in Brest.	Aframax	80,000-120,000	650,000 - 800,000
The Aframax tanker Gerd Knutsen at the wharf in Brest.	Suezmax	130,000-160,000	1,000,000
The informal term Supertanker is generally reserved for vessels over 250,000 dwt.^[9]	VLCC	200,000-320,000	2,000,000
	ULCC	over 320,000	over 2,000,000
	V Plus	over 440,000

Merchant oil tankers carry a wide range of hydrocarbon liquids ranging from crude oil to refined petroleum products.^[1] Their size is measured in deadweight tons (dwt). Crude carriers are among the largest, ranging from 55,000 dwt Panamax-sized vessels to Very Large Crude Carriers (VLCCs) of over 300,000 dwt.^[10]

At the smaller end of the spectrum lie product tankers, carrying refined cargoes range from well under 10,000 dwt to Panamax size.^[10] The smallest tankers, less than 10,000 dwt in capacity, work coastal and inland waterways.^[10] Examples of routes plied by small tankers include the Russian Volgotanker on the Volga River and lake tankers such as those used on Lake Maracaibo in Venezuela in 1923-53.

Supertanker is an informal term for the very largest tankers. Today it is applied to Very-Large Crude Carriers (VLCC) and Ultra-Large Crude Carriers (ULCC) above 250,000 dwt. These ships can transport two million barrels of oil.^[10] By way of comparison, the oil consumption of Spain and the UK combined is about 3.2 million barrels of oil a day.^[11] Ships of the smaller Aframax and Suezmax classes are no longer regarded as "supertankers".

The largest supertanker—indeed the world's largest ship ever —was the Jahre Viking or Seawise Giant (now the permanently moored storage tanker Knock Nevis), weighing in at 564,763 deadweight tons. In the 1950s, tankers with only a tenth of that capacity would have been called supertankers.

The four largest supertankers,^[12] built circa 2002, carry the designation (V Plus), although the term ULCC has not been assigned a maximum dwt.^[13]

When first introduced, their size and draft prevented supertankers from docking at many existing docks, requiring them to discharge their cargo into smaller tankers offshore. Some ports have developed special deep-water off-loading facilities connected to the land by pipelines (such as the Louisiana Offshore Oil Port). Supertankers are also very efficient ships, mostly relying on a single propeller for propulsion, and therefore supertanker transport costs typically account for only US $0.02 per gallon of gas at the pump.^[14]

Current architecture

Oil tankers generally have from 8 to 12 tanks.^[15] Each tank is split into two or three independent compartments by fore-and-aft bulkheads.^[15] The tanks are numbered with tank one being the forwardmost. Individual compartments are referred to by the tank number and the athwartships position, such as "one port," "three starboard," or "six center."^[15]

A cofferdam is a small space left open between two bulkheads, to give protection from heat, fire, or collision.^[15] Tankers generally have cofferdams forward and aft of the cargo tanks, and sometimes between individual tanks.^[16]

A pumproom houses all the pumps connected to a tanker's cargo lines.^[15] Some larger tankers have two pumprooms.^[15] A pumproom generally spans the total breadth of the ship.^[15]

Hull designs

Single hull, Double bottom, and Double hull ship cross sections. Green lines are watertight; black structure is not watertight

A major component of tanker architecture is the design of the hull or outer structure. A tanker with a single outer shell between the product and the ocean is said to be single-hulled.^[17] Most newer tankers are double-hulled, with an extra space between the hull and the storage tanks.^[17] Self-descriptive hybrid designs such as double-bottom and double-sided combine aspects of single and double-hull designs.^[17]

All single-hulled tankers around the world will be phased out by 2026, in accordance with the International Convention for the Prevention of Pollution from Ships, 1973.^[17]

In 1998, the Marine Board of the National Academy of Science conducted a survey of industry experts regarding the pros and cons of double-hull design. Some of the advantages of the double-hull design that were mentioned include:

ease of ballasting in emergency situations,^[18]
reduced practice of saltwater ballasting in cargo tanks decreases corrosion,^[19]
increased environmental protection,^[19]
cargo discharge is quicker, more complete and easier,^[19]
tank washing is more efficient,^[19] and
better protection in low-impact collisions and grounding.^[19]

The same report lists the following as some drawbacks to the double-hull design:

more expensive to build,^[20]
more expensive canal and port expenses,^[20]
ballast tank ventilation difficult,^[20]
ballast tanks need continual monitoring and maintenence,^[20]
increased transverse free surface,^[20]
more surfaces to maintain,^[20]
explosion risk in double-hull spaces if vapor detection system not fitted,^[21]
cleaning mud from ballast spaces a bigger problem.^[21]

In all, double-hull tankers are said to be safer than a single-hull in a grounding incident, especially when the shore is not very rocky.^[22]The safety benefits are less clear on larger vessels and in cases of high speed impact.^[19]^[23]^[24]

Cargo-related operations

File:Unloading tanker.jpg

Cargo flows between a tanker and a shore station by way of marine loading arms attached at the tanker's cargo manifold.

Operations aboard oil tankers are governed by an established body of best practices and a large body of international law.^[25]

Pre-transfer preparation

Prior to any transfer of cargo, the Chief officer must develop a transfer plan detailing specifics of the operation such as how much cargo will be moved, which tanks will be cleaned, and how the ship's ballasting will change.^[26] The next step before a transfer is the pretransfer conference.^[27] The pretransfer conference covers issues such as:

What products will be moved,^[27]
In what order will products be moved,^[27]
Names and titles of key people,^[27]
Particulars of shipboard and shore equipment,^[27]
Critical stages of the transfer,^[27]
Federal, state, and local regulations in effect,^[27]
Emergency and spill-containment procedures,^[27]
Watch and shift arrangements,^[27] and
Shutdown procedures^[27]

After the conference is complete, the person in charge on the ship and the person in charge of the shore installation go over a final inspection checklist. ^[27] In the United States, the checklist is called a Declaration of Inspection or DOI.^[27] Outside of the U.S., the document is called the "Ship/Shore Safety Checklist."^[27] Items on the checklist include:

Proper signals and signs are displayed,^[27]
The vessel is securely moored,^[27]
A language for all communication is chosen,^[28]
All connections are secure,^[28]
Emergency equipment is in place,^[28] and
No repair work is taking place.^[28]

Loading cargo

Loading an oil tanker consists primarily of pumping cargo into the ship's tanks.^[28] As oil enters the tank, the vapors inside the tank must be somehow expelled.^[28] Depending on local regulations, the vapors can be expelled into the atmosphere or discharged back to the pumping station by way of a vapor recovery line.^[28] It is also common for the ship to move water balast during the loading of cargo to maintain proper trim.

Loading starts slowly at a low pressure to ensure that equipment is working correctly and that connections are secure. Then a steady pressure is achieved and held until the "topping-off" phase when the tanks are nearly full.^[28] Topping off is a very dangerous time in handling oil, and the procedure is handled particularly carefully.^[28] Tank-gauging equipment is used to tell the person in charge how much space is left in the tank, and all tankers have at least two independent methods for tank-gauging.^[28] As the tanker becomes full, crew members open and close valves to direct the flow of product and maintain close communication with the pumping facility to decrease and finally stop the flow of liquid.

Unloading cargo

The process of moving oil off of a tanker is similar to loading, but has some key differences.^[29] The first step in the operation is following the same pretransfer procedures as used in loading.^[30] When the transfer begins, it is the ship's cargo pumps that are used to move the product ashore.^[30] As in loading, the transfer starts at low pressure to ensure that equipment is working correctly and that connections are secure.^[30] Then a steady pressure is achieved and held during the operation.^[31] While pumping, tank levels are carefully watched and key locations, such as the connection at the cargo manifold and the ship's pumproom are constantly monitored.^[29] Under the direction of the person in charge, crew members open and close valves to direct the flow of product and maintain close communication with the receiving facility to decrease and finally stop the flow of liquid.^[29]

Tank cleaning

Tanks must be cleaned from time to time for various reasons. One reason is to change the type of product carried inside a tank. Also, when tanks are to be inspected or maintenance must be performed within a tank, it must be not only cleaned, but made "gas-free."^[32]

On most crude-oil tankers, a special crude oil washing (COW) system is part of the cleaning process.^[32] The COW system circulates part of the cargo through the fixed tank-cleaning system to remove wax and asphaltic deposits.^[32]

Tanks that carry less viscous cargoes are washed with water. Fixed and portable water washing systems exist.^[32] Some systems use rotating high-pressure water jets to spray hot water on all the internal surfaces of the tank.^[32] As the spraying takes place, the liquid is pumped out of the tank.^[32]

After a tank is cleaned, it may be gas-freed."^[33] This involves blowing fresh air into the tank to force accumulated gasses out.^[33] Specially trained personnel monitor the tank's atmosphere, often using hand-held gas indicators which measure the percentage of hydrocarbons present.^[33] When this percentage drops below a value specified in tank-vessel regulations, the tank is declared to be gas-free.^[33]

After a tank is gas-free, it may be further hand-cleaned in a process referred to as "mucking." This task is generally done by able seamen and deck officers using tools such as mops, buckets, rags and sponges.

Specialized designs

Naval oilers

A naval oiler (called a fleet tanker in the Royal Fleet Auxiliary) is distinguished from other oil tankers by their ability to deliver fuel while making way in a process known as underway replenishment. Prior to the advent of this technique, naval vessels refuelled while in port or at anchor.

The fleet oiler USS Maumee, launched on April 17, 1915, pioneered the technique of underway replenishment.^[34] A large ship at the time, at 14,500 deadweight tons, Maumee began refuelling destroyers en route to Britain at the outset of World War I.^[34] This technique enabled the Navy to keep its fleets at sea for extended periods, with a far greater range independent of the availability of a friendly port.^[34] This independence proved crucial to victory in World War II by the ships commanded by Fleet Admiral Nimitz who, as Maumee’s executive officer, had played a key role in developing underway replenishment.^[34]

Underway replenishment was quickly adopted by other navies. One example of this is the Australian fleet oiler HMAS Kurumba which provided underway replenishment services in the United Kingdom's Royal Navy from 1917 to 1919.^[35]

Naval oilers may also carry water, ammunition, rations, stores and personnel.^[35]

Ore-bulk-oil carriers

An Ore-bulk-oil carrier, also known as combination carrier or OBO, is a ship designed to be capable of carrying wet or dry cargoes. The idea is to reduce the number of empty (ballast) voyages, in which large ships only carry a cargo one way and return empty for another. These are a feature of the larger bulk trades (e.g. crude oil from the Middle East, iron ore and coal from Australia, South Africa and Brazil).

Combination carriers found themselves specialising in one trade or the other, and their flexibility went very much unused. Very few were built after the 1980s, and the idea has rather fallen out of fashion. One of the more famous OBOs was the Derbyshire MV Derbyshire of 180,000 deadweight tonnes, which in September 1980 became the largest British ship ever lost at sea. It sank in a Pacific typhoon while carrying a cargo of iron ore from Sept-Îles in Canada to Japan.

A fleet of smaller, "river-sized" (several thousand tonnes) ore-bulk-oil carriers have been used for some decades on European Russia's waterways, primarily by Volgotanker. The Russian word for 'ore-bulk-oil carrier', nefterudovoz (нефтерудовоз, literally 'oil/ore carrier'), in combination with a number, is often used as a proper name for a ship, e.g. Nefterudovoz-51M'. ^[36]^[37]

Pollution

File:OilCleanupAfterValdezSpill.jpeg

The Exxon Valdez spilled 10.8 million gallons of oil into Alaska's Prince William Sound.^[38]

From time to time there have been accidents that have led to serious and catastrophic pollution. Another concern has been the pollution caused by careless cleaning of ships' tanks. According to the U.S. Coast Guard, fewer than 67 barrels (about 2,800 gallons) were spilled out of more than 4.2 billion barrels of petroleum delivered by tankers to the U.S. in 2005. The total volume of petroleum spilled from tankers annually in the U.S. has averaged fewer than 4,000 barrels annually from 1996-2005, including no marine incidents during 2005's record hurricane season. In fact, far more oil enters the oceans from natural sources and other incidents than from tanker spills.

However, it is telling that although the Exxon Valdez incident was one of the 20th century's most catastrophic environmental disasters, it could, in fact, have been far worse. Current media reports suggest that some 11 million gallons of oil was dumped on the Alaskan coast in that disaster. This equates to some 35,000 mts of cargo - the Exxon Valdez had the capacity to load about 215,000 mts.

Anti pollution control and measures

Following the Exxon Valdez incident, 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 the Erika (1999) and Prestige (2002), the European Union passed its own stringent anti-pollution packages (known as Erika I, II, and III), which also 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".^[39]

Today's fleet

Flag states

As of 2007, the United States Central Intelligence Agency statistics count 4,295 oil tankers of 1,000 deadweight tons or greater worldwide.^[40] Panama was the world's largest flag state for oil tankers, with 528 of the vessels in its registry.^[40] Six other flag states had more than 200 registered oil tankers: Liberia (464), Singapore (355), China (252), Russia (250), the Marshall Islands (234) and The Bahamas (209).^[40] Former sea-powers the United States and the United Kingdom only had 59 and 27 registered oil tankers, respectively.^[40]

Notes

^ ^a ^b ^c Hayler and Keever, 2003:14-2.
^ Delgado, James (1988). "Falls of Clyde National Historic Landmark Study". Maritime Heritage Program. National Park Service. Retrieved 2008-02-24.
^ Chisholm, 19:316.
^ ^a ^b ^c ^d Chisholm, 19:320.
^ ^a ^b ^c ^d Chisholm, 24:881.
^ Chisholm, 24:881-882.
^ Chisholm, 24:882.
^ Note: definitions of what size of tanker constitute what type e.g. whether a 320,000dwt tanker is VLCC or a ULCC, varies from broker to broker, lawyer to lawyer and ship owner to ship owner. As there is no set, standard, classification, there is no one 'correct' answer. All descriptions of X-size being an X-tanker should be treated with caution.
^ USCG PSIX
^ ^a ^b ^c ^d Hayler and Keever, 2003:14-3.
^ Energy Statistics > Oil > Consumption by country
^ These four sister ships were built by Hellespont Steamship Corporation at the Daewoo shipyard. They are currently named TI Asia, TI Europe, TI Oceania, and TI Africa.
^ Education Section: Basic Glossary. Tankers International.
^ The History Channel. Modern Marvels: Supertankers.
^ ^a ^b ^c ^d ^e ^f ^g Turpin and McEven, 1980:8-24. Cite error: The named reference "tur824" was defined multiple times with different content (see the help page).
^ Turpin and McEven, 1980:8-25.
^ ^a ^b ^c ^d Hayler and Keever, 2003:14-4.
^ "Double-Hull Tanker Legislation: An Assessment of the Oil Pollution Act of 1990 (1998)". Marine Board Commission on Engineering and Technical Systems. Retrieved 2007-04-10.
^ ^a ^b ^c ^d ^e ^f "Double-Hull Tanker Legislation: An Assessment of the Oil Pollution Act of 1990 (1998)". Marine Board Commission on Engineering and Technical Systems. Retrieved 2007-04-10.
^ ^a ^b ^c ^d ^e ^f "Double-Hull Tanker Legislation: An Assessment of the Oil Pollution Act of 1990 (1998)". Marine Board Commission on Engineering and Technical Systems. Retrieved 2007-04-10.
^ ^a ^b "Double-Hull Tanker Legislation: An Assessment of the Oil Pollution Act of 1990 (1998)". Marine Board Commission on Engineering and Technical Systems. Retrieved 2007-04-10.
^ Joem K. Paik and Tak K. Lee, Damage and Residual Strength of Double-Hull Tankers in Grounding, International Journal of Offshore and Polar Engineering, Vol. 5, No. 4, December 1995.
^ [http://www.earthtoys.com/emagazine.php?issue_number=07.02.01&article=green_ships Earthtoys - Emagazine
^ Double, double, oil and trouble in Fairplay International Shipping Weekly, 23 Jun 2005.
^ Hayler and Keever, 2003:14-1.
^ Hayler and Keever, 2003:14-6.
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o Hayler and Keever, 2003:14-7.
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j Hayler and Keever, 2003:14-8.
^ ^a ^b ^c Turpin and McEven, 1980:8-30.
^ ^a ^b ^c Hayler and Keever, 2003:14-9.
^ Hayler and Keever, 2003:14-10.
^ ^a ^b ^c ^d ^e ^f Hayler and Keever, 2003:14-12.
^ ^a ^b ^c ^d Hayler and Keever, 2003:14-13.
^ ^a ^b ^c ^d Navy Dept., Office of the Chief of Naval Operations, Naval History Division. Dictionary of American Naval Fighting Ships Volume 6. ISBN 0160020301. Retrieved 23. {{cite book}}: Check |authorlink= value (help); Check date values in: |accessdate= (help); Cite has empty unknown parameters: |month=, |chapterurl=, and |coauthors= (help); Unknown parameter |accessmonth= ignored (|access-date= suggested) (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help); Unknown parameter |origdate= ignored (|orig-date= suggested) (help); Unknown parameter |origmonth= ignored (help)CS1 maint: multiple names: authors list (link)
^ ^a ^b "Navy Contribution to Australian Maritime Operations". Royal Australian Navy. Retrieved 2008-02-23.
^ Ship listing of the type "Nefterudovoz"
^ [http://www.shipphotos.co.uk/pages/nefterudovoz51m.htm Ship photos - Nefterudovoz-51M
^ "Frequently asked questions about the Exxon Valdez Oil Spill". State of Alaska.
^ European Parliament. 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. Retrieved 02-22-2008. {{cite book}}: Check date values in: |accessdate= (help); Cite has empty unknown parameters: |accessyear=, |origmonth=, |accessmonth=, |month=, |chapterurl=, and |coauthors= (help); Unknown parameter |origdate= ignored (|orig-date= suggested) (help)
^ ^a ^b ^c ^d Central Intelligence Agency, 2007.

References

Sullivan, George (1978). Supertanker!: The Story of the World's Biggest Ships. Dodd, Mead. ISBN 0396075274.
Mitchell, William Harry (1987). Sailing Ship to Supertanker: The Hundred-Year Story of British Esso and Its Ships. Terence Dalton. ISBN 086138055X. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
Double double, toil and trouble. Fairplay International Shipping Magazine. 23 Jun 2005.{{cite book}}: CS1 maint: year (link)
Devanny, Jack (2006). The Tankship Tromedy: the impending disaster in tankers. ISBN 0-9776479-0-0.
European Commission / European Maritime Safety Agency (2005). Double Hull Tankers: High Level Panel of Experts Report.
Encyclopædia Britannica (1911). "Petroleum". In Chisholm, Hugh (ed.). Encyclopædia Britannica. Vol. 21 (11th edition ed.). pp. 316–322. Retrieved 2008-02-22. {{cite encyclopedia}}: |edition= has extra text (help); Cite has empty unknown parameters: |accessmonth=, |month=, |accessyear=, and |coauthors= (help)
Encyclopædia Britannica (1911). "Ship". In Chisholm, Hugh (ed.). Encyclopædia Britannica. Vol. 24 (11th edition ed.). pp. 881–889. Retrieved 2008-02-22. {{cite encyclopedia}}: |edition= has extra text (help); Cite has empty unknown parameters: |accessmonth=, |month=, |accessyear=, and |coauthors= (help)
Hayler, William B. (2003). American Merchant Seaman's Manual. Cornell Maritime Pr. ISBN 0-87033-549-9. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
Office of Data and Economic Analysis (2006). "World Merchant Fleet 2001–2005" (PDF). United States Maritime Administration. Retrieved March 13. {{cite web}}: Check date values in: |accessdate= (help); Cite has empty unknown parameter: |coauthors= (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help); Unknown parameter |month= ignored (help)
Central Intelligence Agency (2007). CIA World Factbook 2008. Skyhorse Publishing. ISBN 1602390800. Retrieved 2008-02-22. {{cite book}}: Cite has empty unknown parameters: |accessyear=, |origmonth=, |accessmonth=, |month=, |chapterurl=, |origdate=, and |coauthors= (help)
Turpin, Edward A. (1980). Merchant Marine Officers' Handbook (4th ed.). Centreville, MD: Cornell Maritime Press. ISBN 0-87038-056-X. {{cite book}}: Check |isbn= value: checksum (help); Cite has empty unknown parameters: |accessyear=, |origmonth=, |accessmonth=, |month=, |chapterurl=, and |origdate= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)

External links

Bill Willis. Supertankers
Intertanko - the society of International Tanker Operators
The International Maritime Organization - Tanker Safety (for double-hulls)

[hay2-1] Hayler and Keever, 2003:14-2.

[foc-2] Delgado, James (1988). "Falls of Clyde National Historic Landmark Study". Maritime Heritage Program. National Park Service. Retrieved 2008-02-24.

[ebpetro316-3] Chisholm, 19:316.

[ebpetro320-4] Chisholm, 19:320.

[ebship881-5] Chisholm, 24:881.

[ebship881a-6] Chisholm, 24:881-882.

[ebship882-7] Chisholm, 24:882.

[8] Note: definitions of what size of tanker constitute what type e.g. whether a 320,000dwt tanker is VLCC or a ULCC, varies from broker to broker, lawyer to lawyer and ship owner to ship owner. As there is no set, standard, classification, there is no one 'correct' answer. All descriptions of X-size being an X-tanker should be treated with caution.

[9] USCG PSIX

[hay3-10] Hayler and Keever, 2003:14-3.

[11] Energy Statistics > Oil > Consumption by country

[12] These four sister ships were built by Hellespont Steamship Corporation at the Daewoo shipyard. They are currently named TI Asia, TI Europe, TI Oceania, and TI Africa.

[13] Education Section: Basic Glossary. Tankers International.

[14] The History Channel. Modern Marvels: Supertankers.

[tur824-15] ^ ^a ^b ^c ^d ^e ^f ^g Turpin and McEven, 1980:8-24. Cite error: The named reference "tur824" was defined multiple times with different content (see the help page).

[tur825-16] Turpin and McEven, 1980:8-25.

[hay144-17] Hayler and Keever, 2003:14-4.

[ho259-18] "Double-Hull Tanker Legislation: An Assessment of the Oil Pollution Act of 1990 (1998)". Marine Board Commission on Engineering and Technical Systems. Retrieved 2007-04-10.

[ho260-19] ^ ^a ^b ^c ^d ^e ^f "Double-Hull Tanker Legislation: An Assessment of the Oil Pollution Act of 1990 (1998)". Marine Board Commission on Engineering and Technical Systems. Retrieved 2007-04-10.

[ho261-20] ^ ^a ^b ^c ^d ^e ^f "Double-Hull Tanker Legislation: An Assessment of the Oil Pollution Act of 1990 (1998)". Marine Board Commission on Engineering and Technical Systems. Retrieved 2007-04-10.

[ho262-21] "Double-Hull Tanker Legislation: An Assessment of the Oil Pollution Act of 1990 (1998)". Marine Board Commission on Engineering and Technical Systems. Retrieved 2007-04-10.

[22] Joem K. Paik and Tak K. Lee, Damage and Residual Strength of Double-Hull Tankers in Grounding, International Journal of Offshore and Polar Engineering, Vol. 5, No. 4, December 1995.

[23] [http://www.earthtoys.com/emagazine.php?issue_number=07.02.01&article=green_ships Earthtoys - Emagazine

[24] Double, double, oil and trouble in Fairplay International Shipping Weekly, 23 Jun 2005.

[hay1-25] Hayler and Keever, 2003:14-1.

[hay6-26] Hayler and Keever, 2003:14-6.

[hay7-27] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o Hayler and Keever, 2003:14-7.

[hay8-28] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j Hayler and Keever, 2003:14-8.

[tur830-29] Turpin and McEven, 1980:8-30.

[hay9-30] Hayler and Keever, 2003:14-9.

[hay10-31] Hayler and Keever, 2003:14-10.

[hay12-32] ^ ^a ^b ^c ^d ^e ^f Hayler and Keever, 2003:14-12.

[hay13-33] Hayler and Keever, 2003:14-13.

[danfs-34] Navy Dept., Office of the Chief of Naval Operations, Naval History Division. Dictionary of American Naval Fighting Ships Volume 6. ISBN 0160020301. Retrieved 23. {{cite book}}: Check |authorlink= value (help); Check date values in: |accessdate= (help); Cite has empty unknown parameters: |month=, |chapterurl=, and |coauthors= (help); Unknown parameter |accessmonth= ignored (|access-date= suggested) (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help); Unknown parameter |origdate= ignored (|orig-date= suggested) (help); Unknown parameter |origmonth= ignored (help)CS1 maint: multiple names: authors list (link)

[aussies-35] "Navy Contribution to Australian Maritime Operations". Royal Australian Navy. Retrieved 2008-02-23.

[36] Ship listing of the type "Nefterudovoz"

[37] [http://www.shipphotos.co.uk/pages/nefterudovoz51m.htm Ship photos - Nefterudovoz-51M

[EVOSTC_FAQ-38] "Frequently asked questions about the Exxon Valdez Oil Spill". State of Alaska.

[39] European Parliament. 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. Retrieved 02-22-2008. {{cite book}}: Check date values in: |accessdate= (help); Cite has empty unknown parameters: |accessyear=, |origmonth=, |accessmonth=, |month=, |chapterurl=, and |coauthors= (help); Unknown parameter |origdate= ignored (|orig-date= suggested) (help)

[cia-40] Central Intelligence Agency, 2007.

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v t e Modern merchant ships
Overviews	Ship Cargo ship Cargo Maritime transport Freight transport Merchant marine Maritime history Shipping line
Dry cargo	Barge Bulk carrier Car float Chain boat Coastal trading vessel Collier Container ship Heavy-lift ship Hopper barge Lake freighter Lighter aboard ship Livestock carrier Reefer ship Roll-on/roll-off (RORO) Train ferry
Tankers	Chemical tanker Floating production storage and offloading (FPSO) Gas carrier Hydrogen tanker LNG carrier Oil tanker
Passenger	Cable ferry Cargo liner Cruise ship Cruiseferry Ferry Narrowboat Ocean liner Roll-on/roll-off (RORO) Train ferry
Support	Anchor handling tug supply vessel Diving support vessel Emergency tow vessel Fireboat Platform supply vessel Pusher Salvage tug Tender Tugboat
Other types	Cable layer Crane vessel Dredger Drillship Fishing vessel Floating restaurant Icebreaker Merchant submarine Narco-submarine Pipe-laying ship Research vessel Riverboat Semi-submersible Snagboat
Related	Nautical operations Affreightment Admiralty law International Chamber of Shipping List of merchant navy capacity by country