In May 1937, "Sicard" entered the Pearl Harbor Navy Yard for conversion to a light minelayer; and, on 20 June, she was reclassified DM-21. Except for a brief trip to the west coast for repairs and training from 20 September to 20 December 1937, "Sicard" operated in the Hawaiian area through 1941, engaging in division tactics and training exercises, fleet problems and maneuvers, joint Army and Navy exercises, battle, torpedo and mining practice, and reconnaissance missions around Midway and outlying islands. She entered the Pearl Harbor Navy Yard on 21 November 1941 and was under overhaul there when the Japanese attacked on 7 December. The ship had ammunition only for her .30-caliber machine guns but aided in the defense of the base by sending men to help operate the guns of the cruiser "New Orleans" (CA-32) and the destroyer "Cummings" (DD-365).