"Wainwright" moved to Boston on 22 May and remained there until 27 July when she got underway for the Connecticut coast. She reached New London, two days later; and, on the 30th, she was commissioned by the Coast Guard. The warship retained her name while serving with the Coast Guard's "Rum Patrol" to suppress the illegal importation of alcoholic beverages. She served at New London from the summer of 1926 until 1929. On 4 January 1929, she headed south to Charleston, South Carolina, whence she conducted gunnery practice until 4 February when she returned north to Boston. In January 1930, she headed south again for gunnery practice but this time at St. Petersburg, Florida. During each of the two succeeding years—in January 1931 and late in March 1932—she returned to St. Petersburg for a month of target practice and afterward resumed her duties along the New England coast.