USS SC-18 [SEP] vessel class
USS SC-18
USS "SC-18, until July 1920 known as USS "Submarine Chaser No. 18 or USS "S.C. 18", was an "SC-1"-class submarine chaser built for the United States Navy during World War I. 
"SC-18" was a wooden-hulled 110-foot (34 m) submarine chaser built at the New York Navy Yard at Brooklyn, New York. She was commissioned on 10 November 1917 as USS "Submarine Chaser No. 18", abbreviated at the time as USS "S.C. 18".
USS SC-501
USS "SC-501" was a "SC-497" class submarine chaser that served in the United States Coast Guard and later the United States Navy during World War II. She was originally laid down as "PC-501" on 29 April 1941 by the Seabrook Yacht Corporation in Houston, Texas, and launched on 24 January 1942. She was reclassified "SC-501" on 8 April 1943, and acquired from the Coast Guard on 9 April 1943. She was reclassified as "Unclassified Miscellaneous Vessel" IX-100 on 21 April 1943