H.M.S. Fly, an 18-gun sloop, was built at Pembroke Dock and launched on 25th August 1831. Measured at 480 tons, she was 114½ feet in length with a 31½ foot beam, mounted 16-32pdr. carronades and 2-9pdrs., and carried a compliment of 120 officers and men when fully crewed. Sent first to the West Indies (1831-35), she spent most of her active service on the South American station where, from 1841-46, she carried out a notable survey of the south-western Pacific, particulary on the Great Barrier Reef where her objective was to chart a safe route into Sydney. Although not engaged on any official survey prior to that date, this log nevertheless illustrates the energetic rôle played by ships like the Fly as they visited the far-flung corners of the Empire to enforce the 'Pax Britannica' throughout the nineteenth century. After a surprisingly short sea-going career, Fly was reduced to a coal hulk (redesignated C.2; later C.70) at Plymouth in 1855 and was eventually broken up in 1903.