46 CFR § 4.03-40
Public vessels
April 15, 2021
Public vessel means a vessel that—
(a) Is owned, or demise chartered, and operated by the U.S. Government or a government of a foreign country, except a vessel owned or operated by the Department of Transportation or any corporation organized or controlled by the Department (except a vessel operated by the Coast Guard or Saint Lawrence Seaway Development Corporation); and
(b) Is not engaged in commercial service.
[CGD 95-028, 62 FR 51195, Sept. 30, 1997]