The Plush Princess was a small, warp capable yacht. The vessel had its own transporter system.
In 2293, when Captain Hikaru Sulu was taken prisoner, retired Captain James T. Kirk and the other former members of the USS Enterprise-A command crew decided to mount a rescue mission. Needing a ship, Spock and Montgomery Scott borrowed the Plush Princess from a local businessman.
Kirk and his former shipmates were able to rescue Sulu; however, the Plus Princess was heavily damaged in the rescue attempt. After returning to Earth, Starfleet was reluctant to repair the ship, but Spock and Scott talked them into doing so. (TOS novel: The Fearful Summons)