Ex-DM 20, former USS Harlequin, ex-AM 365 and ex ID-20. She belonged to the Admirable-class minesweepers built in 1954 and used by the Mexican navy as patrol vessels, later was disarmed for use as a survey vessel and with a crew numbered 62 men. As a patrol vessel were her displacement 650 (standard)-900 (full load) tons with as dimensions 56,3 x 10,1 x 4,4 metres or 184.5 x 23 x 14.4 feet. The two Cooper Besemer GSB-8 diesels supplied via two shafts 1,710 bhp allowing a speed of maximum 15 knots or with a speed of 10 knots a range of 4,300 nautical miles. Steel hull-build.
