Double-hulled tanker Double-hulled tanker A double-hulled tanker refers to an oil tanker which has a double hull. They reduce the likelihood of leaks occurring than in single-hulled tankers, and their ability to prevent or reduce oil spills led to double hulls being standardized for oil tankers and other types of ships including by the International Convention for the Prevention of Pollution from Ships or MARPOL Convention. After the Exxon Valdez oil spill disaster in Alaska in 1989, the US Government required all new oil tankers built for use between US ports to be equipped with a full double hull. A number of
Oil tanker instrument, Shell consulted the "London Tanker Brokers’ Panel (LTBP)". At first, they divided the groups as "General Purpose" for tankers under ; "Medium Range" for ships between 25,000 and and "Large Range" for the then-enormous ships that were larger than . The ships became larger during the 1970s, which prompted rescaling. The system was developed for tax reasons as the tax authorities wanted evidence that the internal billing records were correct. Before the New York Mercantile Exchange started trading crude oil futures in 1983, it was difficult to determine the exact price of oil, which could change with every contract.