46 CFR §67.161

1. (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:
   1. (1)46 U.S.C. chapter 125;
   2. (2)46 U.S.C. chapter 313 for an instrument filed or recorded before the date of invalidation, and an assignment or a notice of claim of lien filed after that date;
   3. (3)46 U.S.C. 56101, 56102 and 57109; and
   4. (4)46 U.S.C. 56301.
2. (b)The provisions of paragraph (a) of this section do not apply to a vessel which is subject only to a mortgage filed or recorded before January 1, 1989, which had not attained preferred status as of that date.