Raper was born in 1767, entered the navy in February 1780, on board the Berwick, which in July joined the flag of Sir George Rodney in the West Indies.
From 1785 to 1788 he was in the Salisbury, the flagship of Rear-admiral John Elliot, at Newfoundland, and afterwards in the Impregnable and Queen Charlotte in the Channel till 22 November 1790, when he was promoted to the rank of lieutenant.
In November 1795 he commanded the Racoon in the Thames; and on 1 February 1796 was posted to the Champion, a small frigate employed on the coast of Ireland and afterwards in the North Sea.
264); and in the following May took part in the attempt to destroy the locks and sluice-gates of the Bruges-Ostend Canal.p From January 1799 to September 1802 he commanded the Aimable in the West Indies (James, Nav.
In 1810 he declined an offer of the rank of vice-admiral in the Portuguese service; and was in November appointed to the Mars, which he commanded till February 1813, on the Lisbon station and in the Baltic.