HMS Racehorse was an 18-gun ship-rigged  sloop of the Royal Navy, later refitted as a survey vessel. She was originally the 18-gun French privateer  Marquis de Vaudreuil, captured from the French in 1757 during the Seven Years War, and purchased for the British Navy on 28 April 1757. As she was a three-masted vessel, she was described as a ‘frigate’, but as she mounted just 18 guns, she was actually registered as a sloop.