46 U.S.C. § 12139 — Reports

(a) In general. To ensure compliance with this chapter and the laws governing coastwise trade and fishery qualifications, the Secretary may require owners, masters, charterers, and mortgagees of documented vessels to submit reports in any reasonable form and manner the Secretary sets. (b) Vessels rebuilt outside United States. (1) Under Secretary regulations, if a documented — or last-documented — vessel over the tonnage described in (2) is rebuilt outside the United States, the owner or master must report the rebuilding to the Secretary. (2) That tonnage is 500 gross tons as measured under section 14502, or an alternate tonnage the Secretary sets under section 14104 using section 14302. (3) If the rebuilding finishes in the United States, the report is due when it finishes. If the rebuilding finishes outside the United States, the report is due when the vessel first arrives at a US customs port.