The USS Merrimac (NCC-1715) was a 23rd century Federation starship operated by Starfleet. It was classified as a cruiser.
In the mid-2270s, the Merrimac was mentioned in comm chatter intercepted by the Epsilon IX station. (Star Trek: The Motion Picture)
This starship was only mentioned in dialogue.
The comm transmission of this starship was trimmed from the director's cut.