46 U.S.C. § 57109

Unless otherwise authorized by the Secretary of Transportation, a vessel purchased, chartered, or leased from the Secretary may be operated only under a certificate of documentation with a registry or coastwise endorsement. Such a vessel, while employed solely as a merchant vessel, is subject to the laws, regulations, and liabilities governing merchant vessels, whether the United States Government has an interest in the vessel as an owner or holds a mortgage, lien, or other interest.