Y Class, or Class Y starships were freighters deployed by the Earth Cargo Service in the 22nd century. Y class ships were built to replace the earlier J-class starships that had been used by Earth's cargo service in the early 22nd century. The design principles of a Class Y were similar to those of the earlier class J ships - with the major difference being that the Y class was a larger vessel. The Y class freighter was also known as Fortunate class. (ST video game: Legacy)