page_title: Oil tanker
section_title: Ore-bulk-oil carriers
hierarchical_section_title: Oil tanker / Special-use oil tankers / Ore-bulk-oil carriers
caption_attribution_description: English: The Ore/Bulk/Oil carrier Maya in Brest. Soya in being carried in the central holds and ballast in lateral tanks. Français&#160;: Le transporteur combiné pétrole/vrac/minerai (OBO) Maya à Brest. Du soja est ici transporté dans la soute centrale, et le ballast dans les citernes latérales.
context_page_description: An oil tanker, also known as a petroleum tanker, is a ship designed for the bulk transport of oil or its products. There are two basic types of oil tankers: crude tankers and product tankers. Crude tankers move large quantities of unrefined crude oil from its point of extraction to refineries. For example, moving crude oil from oil wells in a producing country to refineries in another country. Product tankers, generally much smaller, are designed to move refined products from refineries to points near consuming markets. For example, moving gasoline from refineries in Europe to consumer markets in Nigeria and other West African nations.
  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 metric tons of deadweight to the mammoth ultra large crude carriers of 550,000 DWT. Tankers move approximately 2.0 billion metric tons of oil every year. Second only to pipelines in terms of efficiency, the average cost of transport of crude oil by tanker amounts to only US$5 to $8 per cubic metre.
  Some specialized types of oil tankers have evolved.
context_section_description: An ore-bulk-oil carrier, also known as combination carrier or OBO, is a ship designed to be capable of carrying wet or dry bulk cargoes. This design was intended to provide flexibility in two ways. Firstly, an OBO would be able to switch between the dry and wet bulk trades based on market conditions. Secondly, an OBO could carry oil on one leg of a voyage and return carrying dry bulk, reducing the number of unprofitable ballast voyages it would have to make.
  In practice, the flexibility which the OBO design allows has gone largely unused, as these ships tend to specialize in either the liquid or dry bulk trade. Also, these ships have endemic maintenance problems. On one hand, due to a less specialized design, an OBO suffers more from wear and tear during dry cargo onload than a bulker. On the other hand, components of the liquid cargo system, from pumps to valves to piping, tend to develop problems when subjected to periods of disuse. These factors have contributed to a steady reduction in the number of OBO ships worldwide since the 1970s.
  One of the more famous OBOs was MV Derbyshire of 180,000 DWT 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 Canada to Japan.
caption: The OBO-carrier Maya. The picture is showing both the cargo hold hatches used for bulk and the pipes used for oil
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