For the purposes of this chapter the term “vessel of the United States” shall mean any private vessel documented or certificated under the laws of the United States. Notwithstanding any other law, the documentation or certification of any such vessel shall not be considered to be affected, for the purposes of this chapter, in any manner or to any extent if at any time during any voyage for the purpose of fishing beyond the fishery conservation zone (as defined in section 1802(8)  of title 16), the vessel is commanded by other than a citizen of the United States.1