The Lapwing-class minesweeper, often called the Bird class, was an early "AM-type" oceangoing minesweeper of the United States Navy. Seven ships of the class were commissioned during World War I, and served well into the 1950s. A number were refitted to serve as ocean-going tugs, salvage vessels, seaplane tenders, or submarine rescue ships. The propulsion system consisted of 2 Babcock & Wilcox 200psi boilers and a 1,400shp Harlan and Hollingsworth triple expansion reciprocating steam engine. Ships The table makes no distinction between classification as "Minesweeper No. X" and "AM-X". This change affected all boats equally ca. 1920. All boats reclassified as Fleet Tugs (AT) where later again reclassified as Fleet Tug, Old (ATO) (ca. 1944). The table treats them the same. Brant and Grebe were never reclassified as ATO. References External links USN Ships Ships of the U.S. Navy, 1940–1945 Mine warfare vessel classes