46 U.S.C. § 58103

(a) Prohibition .— Except with the written consent of the Secretary of Transportation, a contractor holding a contract under the operating-differential subsidy program or under chapter 575 of this title may not— (1) employ another person as the managing or operating agent of the operator; or (2) charter a vessel, on which an operating-differential subsidy is to be paid, for operation by another person. (b) Applicability of Provisions to Charterer .— If a charter prohibited by this section is made, the person operating the chartered vessel is subject to all the provisions of this subtitle and the operating-differential subsidy program, including limitations of profits and salaries.