The first USS Dorchester (SP-1509) was a schooner that served in the United States Navy as a patrol vessel from 1917 to 1918. Dorchester was a Chesapeake Bay "Bugeye"-type schooner built in 1893. The U.S. Navy acquired her from the Conservation Commission of Maryland on 24 August 1917 for World War I service as a patrol vessel. She was commissioned the same day as USS Dorchester (SP-1509). Dorchester served in the 5th Naval District for the remainder of World War I, patrolling waters in Maryland and Virginia.