(a) In accordance with 10 U.S.C. 2631(a) , DoD contractors shall transport supplies exclusively on U.S.-flag vessels. In accordance with 10 U.S.C. 2631(b) , DoD (see 247.573(a)) may waive this requirement when a U.S.-flag vessel- (1) Is not available at a fair and reasonable rate for commercial vessels of the United States; or(2) Is not otherwise available.(b) Contracts must provide for the use of vessels belonging to the United States when security classifications prohibit the use of other than vessels belonging to the United States.(c) In accordance with 10 U.S.C. 2631(c) - (1) Any vessel used under a time charter contract for the transportation of supplies under this section shall have the following work performed in the United States or its outlying areas: (i) Reflagging or repair work, if the reflagging or repair work is performed- (A) On a vessel for which the contractor submitted an offer in response to the solicitation for the contract; and(B) Prior to acceptance of the vessel by the Government.(ii) Corrective and preventive maintenance or repair work for the duration of the contract, to the greatest extent practicable.(2) The Secretary of Defense may waive this requirement if the Secretary determines that such waiver is critical to the national security of the United States. In accordance with 10 U.S.C. 2631(c)(2) , DoD shall immediately submit, in writing, a notice to the congressional committees listed at 10 U.S.C. 2631(e) of such a waiver and the reason for the waiver.(d) In accordance with section 1017 of the National Defense Authorization Act for Fiscal Year 2007 (Pub. L. 109-364), when obtaining carriage requiring a covered vessel, the contracting officer shall consider the extent to which offerors have had overhaul, repair, and maintenance work for covered vessels performed in shipyards located in the United States or Guam.(e) In accordance with section 3504 of the National Defense Authorization Act for Fiscal Year 2009 (Pub. L. 110-417), DoD may not award, renew or extend, or exercise an option under a charter of, or contract for carriage of cargo by, a U.S.-flag vessel documented under 46 U.S.C. chapter 121, unless the contract contains the clause at 252.247-7027. 65 FR 50146 , Aug. 17, 2000, as amended at 70 FR 35545 , June 21, 2005. Redesignated and amended at 72 FR 49206 , Aug. 28, 2007; 73 FR 70911 , Nov. 24, 2008; 75 FR 65438 , Oct. 25, 2010; 78 FR 37990 , June 25, 2013; 79 FR 61583 , Oct. 14, 2014