46 C.F.R. § 140.105
Applicability and delayed implementation for existing vessels
This part applies to all towing vessels subject to this subchapter.
(a) With the exception § 140.500, which has a later implementation date, an existing towing vessel must comply with the requirements in this part no later than either July 20, 2018 or the date the vessel obtains a Certificate of Inspection (COI), whichever date is earlier.
(b) The delayed implementation provisions in paragraph (a) of this section do not apply to a new towing vessel.