Fleet Operations Centre
The Zabathu is the most common type of tug employed by 25th century Starfleet. As a tug, it is specialized for towing other vessels and is a highly maneuverable ship with powerful tractor beam generators. Zabathus are not meant for combat and only lightly armed, with its combat performance comparable to that of a runabout. The name of the class originates from an Andorian mount and pack animal.
Most Starfleet orbital and deep space stations have Zabathus attached to them. On a regular basis, they assist large ships with docking using their tractor beams in conjunction with those of the docking facility. They are deployed to longer ranges for the purposes of towing disabled starships, clearing debris fields or other tasks that required a vessel to move large objects for an extended period of time. Zabathus do not operate independently and rarely have a dedicated crew; like escorts and runabouts attached to stations, the crew is picked from the station roster, with the commanding officer generally being a senior engineer with bridge training.
Mobile Repair Carrier
The Saturn is by definition a carrier and is based on the design of the Jupiter-class carrier, but it is primarily meant to carry out field repairs. Instead of fighters, Saturns possess more work bees and more cargo space to store materials for repair work. The Jupiter's bays for Callisto escort craft were redesigned to become miniature drydocks for smaller escorts such as Sabers and Defiants who can dock with the carrier for thorough repairs.
Only one Saturn-class vessel has been built so far, the prototype U.S.S. Saturn.