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
Exxon Valdez oil spill effectively a bill of attainder, a regulation that was unfairly directed at Exxon alone. In 2002, the 9th Circuit Court of Appeals ruled against Exxon. As of 2002, OPA had prevented 18 ships from entering Prince William Sound. OPA also set a schedule for the gradual phase in of a double hull design, providing an additional layer between the oil tanks and the ocean. While a double hull would likely not have prevented the "Valdez" disaster, a Coast Guard study estimated that it would have cut the amount of oil spilled by 60 percent. The "Exxon Valdez" supertanker was towed