Horizon Offshore, Inc. announced the board of directors has elected J. Louis Frank as chairman of the board. Replacing outgoing chairman, James Devine, a UK national, with Frank, a U.S. citizen, allows Horizon to meet certain U.S. regulatory requirements relevant to a recently awarded contract. Mr. Devine remains a member of the board of directors. Also elected to the board of directors was John T. Mills. Mr. Mills is senior vice president and chief financial officer of Marathon Oil Corporation. Mr. Mills joined Marathon Oil Company in 1976 as a tax specialist. He became chief tax counsel in 1984.