A yacht was a type of boat.
The Britannia was the royal yacht of King Edward VIII. (PROSE: The Church of Football)
FAB 2 was Lady Penelope Creighton-Ward's yacht. (TV: The Man from MI.5, COMIC: The Great Silver Robbery!, etc.)
In an account dated to January 1965, MI5 agent Captain Blacker owned a yacht, which was blown up in a scheme by criminal gang leader Carl. (TV: The Man from MI.5)
Other sources dated the activities of International Rescue to the 1990s, (PROSE: The Dying Days) the 2060s, (PROSE: Titan Declares War! et al.) and the 2080s. (PROSE: Captain Scarlet in Death Crash! et al.)
Henry Palmerdale's steam yacht struck against Fang Rock while en route to Southampton due to a blanket of fog. The passengers were forced to abandon the vessel. Harker, the yacht's bosun, refused to take it out to sea again while the conditions persisted. (TV: Horror of Fang Rock)
When Missy travelled through time stealing several artefacts from Earth's history, the Twelfth Doctor wondered if, among other things, she was planning to sell them to buy a yacht and travel the world, although the Doctor thought this was unlikely. (PROSE: Dr. Twelfth)