American Geological Institute

Government Affairs Program

NRC Report "Double-Hull Tanker Legislation: An Assessment of the Oil Pollution Act of 1990"

After the Exxon Valdez oil spill, Congress promulgated the Oil Pollution Act of 1990, which intended to "minimize oil spills through improved tanker design, operational changes, and greater preparedness." Section 4115 of the act focuses on ship design, changing the standard from single to double hulls. By 2010, single-hull tankers greater than 5,000 gross tons will be excluded from U.S. waters unless they are equipped with a double bottom or double sides. Because this provision affects both domestic and international fleets, Congress ordered the U.S. Department of Transportation (DOT) to assess its economic and operational impacts. The DOT, acting through the Coast Guard, then requested the advice of the National Research Council.

Report Findings
The committee found that properly designed double hulls are potentially more effective than single hulls in preventing and mitigating oil spills after a vessel accident. Many existing double hull vessels, however, are not designed properly. The committee recommended quickly developing new technical guidelines for the construction of these vessels. The report also found that because most tankers in international trade will be retired before their statutory retirement dates, the legislation will not affect their life expectancy. Costs will increase because the capital cost of a double-hull tanker are estimated to be 9-17% higher than a single tanker, and maintenance and operation costs run 5-13% higher. The impact on domestic fleets will be slightly larger, due to requirements in the Jones Act. The committee recommended appointing an independent panel to examine policy options that would "ensure that enough U.S. built vessels will be available when needed." A final recommendation by the committee was to increase the amount of data on oil spills and vessel design available.

The report was prepared by the Committee on Oil Pollution Act of 1990 Implementation chaired by Douglas Wolcott, former president of Chevron Shipping, under the direction of the Marine Board. Committee members had expertise in a variety of areas, including tanker fleet management, tank vessel design, economics, marine safety, natural resource damage assessment, and international marine conventions. Additional information and order forms are available from the National Academy Press at 800-624-6242 and on the NAP web site. Copies are $34.00 plus a shipping charge of $4.00 for the first copy and $.50 for each additional copy.

Please send any comments or requests for information to the AGI Government Affairs Program at

Contributed by Kasey Shewey, AGI Government Affairs.
Last updated December 12, 1997

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