sentences:  The first Navy ship to be named Mockingbird, "AMc-28", a wooden dragger built in 1936 as "Rio Douro" by Morse Shipyards, Thomaston, Maine, was purchased by the U.S. Navy from L. C. McEwen and A. M. Pereira of Gloucester, Massachusetts, 30 October 1940; converted to a coastal minesweeper by the General Ship & Engine Works, East Boston, Massachusetts; renamed "Mockingbird" 14 November 1940; and placed in service at Boston 12 June 1941.