46 U.S.C. § 31305
Waiver of lien rights
This chapter does not prevent a mortgagee or other lien holder from waiving or subordinating at any time by agreement or otherwise the lien holder’s right to a lien, the priority or, if a preferred mortgage lien, the preferred status of the lien.
( Pub. L. 100–710, title I, § 102(c) , Nov. 23, 1988 , 102 Stat. 4741 .)