NCC-1718 was the registry number of a Federation starship that was in service to Starfleet in the mid-23rd century. This unnamed starship underwent a layover at Starbase 11. The ship's number was seen on a chart indicating the repair status of several vessels. (TOS: "Court Martial")
The registry NCC-1718, displayed on Commodore Stone's chart.
Unfortunately, we don't know what this ship was named since it was only identified by its hull number. According to Franz Joseph's Star Fleet Technical Manual, this number was assigned to a Constitution-class heavy cruiser named the USS Excelsior. In Greg Jein's interpretation of the starbase chart in The Case of Jonathan Doe Starship, he named the vessel USS Endeavour.