NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the panel responsible for the report were chosen for their special competencies and with regard for appropriate balance.

This report has been reviewed by a group other than the authors according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine.

The project is part of a program supported by interagency agreement No. DTMA91-94-G00003, which is managed on behalf of participating agencies by the Maritime Administration of the Department of Transportation; and grant No. N00014-95-1-1205 between the Navy and the National Academy of Sciences. Financial support from the American Bureau of Shipping to cover the costs of report publication is gratefully acknowledged. The views expressed herein do not necessarily reflect the views of the sponsors and no official endorsement should be inferred.

Limited copies are available from: Marine Board, Commission on Engineering and Technical Systems, National Research Council, 2101 Constitution Avenue, Washington, D.C. 20418