Tanker Size:There are different tanker sizes used for the international transportation of oil, from a modest coastal tanker to a VLCC or ULCC Supertanker. The common rule is that the volume that can be carried in a tanker increases as a function of the cube of its length. For instance, a ULCC is about twice the length of a coastal tanker (415 meters versus 205 meters), but can carry about 8 times the volume (50,000 deadweight tons versus 400,000 dwt).The largest ship ever built was an oil tanker; the Knock Nevis built in 1979 (christened as the Seawise Giant) with 565,000 of dwt, a length 458 meters, a beam of 69 meters and a draught of 25 meters. The ship was so large that no port could accommodate it fully laden, so it was loaded and unloaded while anchored offshore. In 2004 the Knock Nevis was converted to a floating storage and mooring unit of the coast of Qatar until 2009 when it was scrapped. As of 2010, only 12 tankers above 320,000 dwt remained. Of this, only two "true" ULCC of around 430,000 dwt are left in operation, the TI Europe and the TI Oceana, which were part of a group of four ships constructed between 2002 and 2003. The other two ships, TI Africa and TI Asia were converted into floating storage and mooring units in 2010. Oil tankers have a commercial life expectancy of about 30 years. Because of their huge mass, tankers have a large inertia, making them very difficult to steer. A loaded supertanker could take as much as 4 to 8 kilometers and 15 minutes to come to a full stop and has a turning diameter of about 2 kilometers.

Among the main tanker classes are:

Class Length Beam Draft Overview

Coastal Tanker

205 m 29 m 16 mLess than 50,000 dwt, mainly used for transportation of refined products (gasoline, gasoil).

Aframax 245 m 34 m 20 mApproximately 80,000 dwt (Average Freight Rate Assessment).

Suezmax 285 m 45 m 23 mBetween 125,000 and 180,000 dwt, originally the maximum capacity of the Suez Canal.

VLCC 330 m 55 m 28 m

Very Large Crude Carrier. Up to around 320,000 dwt. Some can be accommodated by the expanded dimensions of the Suez Canal. The most common length is in the range of 300 to 330 meters.

ULCC 415 m 63 m 35 mUltra Large Crude Carrier. Capacity exceeding 320,000 dwt. The largest tankers ever built have a deadweight of over 550,000 dwt.

Tankers

These vessels carry refined petroleum products in numerous bulk tanks for safety and in order to carry a number of different products in a single voyage.

Tankers of less than 100,000 dwt are referred to as either "clean" or "dirty". Clean tankers carry refined petroleum products such as gasoline, kerosene, jet fuels, or chemicals. The so-called dirty vessels transport products such as heavy fuel oils or crude oil. Larger tankers usually only carry crude oil.

Coastal Size: 3,001 dwt - 10,000 dwt

These are the smallest tankers and are generally used in coastal waters requiring a shallow draft. Coastal tankers typically carry kerosene, heating oils, fuels and chemicals.

Small Size: 10,001 dwt - 19,000 dwt

This is the next size up tanker and is still often used in coastal waters. These also typically carry kerosene, heating oils, fuels and chemicals.

Handy or Handysize

Size: 19,001 dwt - 25,000 dwt

Alternate: 10,000 - 34,999 dwt

This is a popular-sized tanker, but typically not used in very long voyages

Medium or Handymax

Size: 25,001 dwt - 45,000

Alternate: 35,000 - 49,999 dwt

This is a larger "Handy" sized vessel.

Large/Long Range One (LRI)

Size: 45,001 - 70,000 dwt

Alternate: 45,000 to 79,999

Large/Long Range Two (LRII)

Size: 70,001 - 100,000+ dwt

Alternate: 80,000 - 159,999

Crude Oil Carriers

These vessels carry bulk crude oil in tanks.

Tankers of less than 100,000 dwt are referred to as either "clean" or "dirty". Clean tankers carry refined petroleum products such as gasoline, kerosene or jet fuels, or chemicals. The so-called dirty vessels transport products such as heavy fuel oils or crude oil. Larger tankers usually only carry crude oil.

Panamax

Size: 50,001 - 80,000 dwt

Approximate 32.2m beam limitation

This is the maximum size ship that can pass through the locks of the Panama Canal. Locks are 1000ft long by 110ft wide and 85ft deep. Panamax dimensions are: overall length (LOA) of 965ft (290m); beam of 106ft (32.3m); draft of 39.5ft (12.04m).

Aframax

Size: 80,000 - 119,000 dwt

This is the largest crude oil tanker size in the AFRA (Average Freight Rate Assessment) tanker rate system.

Suezmax

Size: 120,000 dwt - 150,000 dwt

This is the maximum size crude oil ship that can pass through the Suez Canal in Egypt.

Very Large Crude Carrier (VLCC)

Size: 150,000 - 320,000 dwt

These are very large crude oil carriers that transport crude oil from the Gulf, West Africa, the North Sea and Prudhoe Bay to destinations in the United States, Mediterranean Europe and Asia. Although VLCCs are otherwise too large, it is possible to ballast these vessels through the Suez Canal.

Ultra Large Crude Carrier (ULCC)

Size: 321,000+ dwt

These are the largest man-made vessels that move. Currently, the largest ULCC is 564,939 dwt. These ships sail the longest routes, typically from the Gulf to Europe, the United States and Asia. They are so large that they require custom-built terminals for loading and unloading.