A Starfleet tug tows the USS Fredrickson
Federation tugs were the workhorses of the Federation used exclusively to tow damaged or diabled vessels.
In the 23rd century, the Starfleet utilized Ptolemy-class starship's as combined tug-transports. (Star Trek II: The Wrath of Khan)
By the 24th century, specialized tugs were readily used for assistance during the Dominion War for towing disabled vessels from battle zones. The USS Fredrickson was one such starship to benefit from these utility vessels in 2374. (DS9:"A Time to Stand")