The Cran had their own ship.
After encountering her mother, Heather McCrimmon returned to the Tenth Doctor, who was uncovering a plot by the Cran to steal Earth's rain clouds. Heather and the Doctor boarded the CranShip and disarmed the Cran by channelling lightning from the clouds they were stealing. They then brought the Cran to the Shadow Proclamation. (COMIC: The Great Rain Robbery)