Why does the Oil Pollution Act require certain oil tankers to have double hulls?

The Oil Pollution Act requires certain oil tankers to have double hulls to prevent or minimize the release of oil into the marine environment during accidents, such as groundings or collisions.12

In a double-hulled ship, the sides and bottom are constructed with two layers separated by a space. This design significantly reduces the likelihood that an incident breaching the outer layer will also breach the inner layer, thereby maintaining the integrity of the cargo tanks and preventing spills.3

The U.S. Congress passed the Oil Pollution Act in 1990 as a direct response to the Exxon Valdez oil spill, which resulted in the release of nearly 11 million gallons of crude oil into Prince William Sound. By mandating double hulls, the act aims to protect ecosystems and wildlife from the devastating impacts of such environmental disasters. This requirement aligns with broader international efforts, such as the amendments to the International Convention for the Prevention of Pollution from Ships, which have worked to phase out single-hulled tankers globally.123