The provisions of section 6(b)(2) prescribe special methods for
computing minimum wages and hours worked under the Act which are
applicable only to seamen who are employed on American vessels. An
``American vessel'', which would appear to signify a vessel of the
United States as distinguished from a foreign vessel, ``includes'',
under the terms of the definition in section 3(p) of the Act, ``any
vessel which is documented or numbered under the laws of the United
States.'' The Department of the Treasury, Bureau of Customs and the
United States Coast Guard, respectively, are responsible for
documentation and numbering of vessels.