The s were constructed after the s. Mariposa cost $926,446 to construct and had an overall length of 180feet. She had a beam of 37feet and a draft of up to 12feet at the time of construction, although this was increased to 14inchesft7inchesin (ftin) in 1966. She initially had a displacement of 935lt; this was increased to 1026lt in 1966. She was powered by one electric motor. This was connected up to two Westinghouse generators which were driven by two CooperBessemer GND-8 four-cycle diesel engines. She had a single screw.[2]
The Iris-class buoy tenders had maximum sustained speeds of 13kn, although this diminished to around 11.9kn in 1966. For economic and effective operation, they had to initially operate at 8.3kn, although this increased to 8.5kn in 1966. The ships had a complement of six officers and seventy-four crew members in 1945; this decreased to two warrants, four officers, and forty-seven men in 1966. They were fitted with a SL1 radar system and QBE-3A sonar system in 1945. Their armament consisted of one 3-inch/50-caliber gun, two 20 mm/80 guns, two Mousetraps, two depth charge tracks, and four Y-guns in 1945; these were removed in 1966.[2]
Upon receiving her commission Mariposa was assigned to the 3rd Coast Guard District and homeported at Staten Island where she was used for general ATON until the end of World War II.[1] After the end of the war, she stayed in Staten Island. In 1990, she underwent a major renovation and from June 1991, until being decommissioned, she was stationed at Seattle.[1] In 2000, she was transferred to the U.S. Navy for use as a training hulk.[1]