46 CFR §67.145

1. (a)A Certificate of Documentation issued to a vessel which is the subject of an outstanding mortgage recorded pursuant to subpart Q of this part or predecessor regulations, may not be exchanged for a cause arising under §§ 67.167(b) (1) through (5) or 67.167(c) (1) through (8) without the consent of the mortgagee, except as provided in paragraph (b) of this section.
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.
3. (c)When the owner of a vessel applies for a Certificate of Documentation and the consent of the mortgagee is required under paragraph (a) of this section, the applicant must submit a properly completed original Application, Consent, and Approval for Withdrawal of Application for Documentation or Exchange of Certificate of Documentation (form CG-4593) signed by or on behalf of the mortgagee to the National Vessel Documentation Center.