HMS Racehorse (1757)

HMS Racehorse was an 18-gun sloop of the Royal Navy, later refitted as a survey vessel. She was originally the 18-gun French privateer Marquis de Vaudreuil, presumably captured from the French at some point in the Seven Years' War, and purchased for the navy on 28 April 1757.

She was part of a voyage of exploration in 1773, commanded by Constantine John Phipps, that unsuccessfully attempted to find a northwest passage from the Atlantic Ocean to the Pacific Ocean. A young Horatio Nelson served as a midshipman aboard the second ship of the small squadron, HMS Carcass (1759) under captain Skeffington Lutwidge, second in command of the Phipps expedition.

The expedition left the Nore on 10 June and passed along the western coast of Svalbard and advanced to latitude 80°50'N before reaching impenetrable ice front. They came in sight of Sjuøyane off Svalbard's north coast and midshipman John Walden, along with two pilots, landed on the westernmost island on 5 August of the same year. The island later known as Waldenøya (Walden Island).

Other Islands named after expedition members are Phippsøya and Nelsonøya of Sjuøyane. Additionally, Cummingøya is named after watchmaker Alexander Cummings, who made the pendulum used by Phipps' expedition. According to Gerard De Geer's 1913 Spitzbergen map, this is the island where Phipps tried to make a pendulum observation.

Racehorse was renamed Thunder and reclassed as bomb vessel in 1775. Thunder, while under Commander James Gambier, was captured off Sandy Hook on 14 August 1778 by the French 74-gun ship Hector and Vaillant, part of the squadron under the Comte d'Estaing.