((a)) ** .—** 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)) ** .—** 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.