Following post-shakedown repairs and alterations, "Andres" then conducted further training off Rockland, Maine, and put of New London, Connecticut, before she proceeded to Miami, Florida, arriving there on 10 June 1943 for duty with the Operational Training Command, Atlantic Fleet. She then operated principally in the Florida Straits area as a school ship at the Submarine Chaser Training School (SCTS), Miami, Florida, indoctrinating student officers and nucleus crews, and interspersed this training with periodic overhauls at the Charleston Navy Yard, South Carolina, (19–29 March, 25 June – 1 July, and 16–26 October 1944).