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
Milford Haven Waterway first oil terminal and oil refinery in 1960; unfortunately this coincided with a serious oil-spill from "Esso Portsmouth", the first oil tanker to unload there. Since then, there have been numerous spills of varying magnitude, providing the port authority with a great deal of experience. Uniquely at the time, the harbourmaster instituted the principle of cleaning up first and allocating the blame (and the responsibility of paying for it) later. There are two large oil refineries nearby which represent one fifth of the United Kingdom's oil refining capacity. In 1978 the tanker "Christos Bitas" ran aground off the Haven, spilling