46 C.F.R. § 67.161
(a) Notwithstanding any other provision of this subpart, except as provided in paragraph (b) of this section, a Certificate of Documentation but no trade endorsement thereon, issued to a vessel which is the subject of an outstanding mortgage filed or recorded in accordance with subpart Q of this part or any predecessor regulations, remains valid for purposes of:
[CGD 89-007, CGD 89-007a, 58 FR 60266, Nov. 15, 1993, as amended by USCG-2016-0531, 82 FR 43864, Sept. 20, 2017]