46 U.S.C. § 56501Section
§ 56501. Definition
In this chapter, the term "essential vessel" means a vessel that is—
(1)(A) security for a mortgage indebtedness to the United States Government; or
(B) constructed under this subtitle or required by a contract under this subtitle to be operated on a certain essential foreign trade route; and
(2) necessary in the interests of commerce and national defense to be maintained in condition for prompt use.
(Pub. L. 109–304, §8(c), Oct. 6, 2006, 120 Stat. 1656.)
