Following the creation of the United Federation of PlanetsEarth Starfleet began the process of updating its fleet to newer standards using now more widely available technology from other Federation planets. The NV or Intrepid-class was one of the first to receive such refits, falling behind the already more advanced NX class. Though these refits included updated technology based on alien technology such as Vulcan shield technology much of the upgrades were revolutionized by the NX-01 Enterprise and her sister ships, as such the refits were called NX Refits. The final refitted Intrepids were twice as effective in combat and in exploration then they were prior to the refit.
The Refit of the Intrepid class is inspired by one John Eaves' rejected concepts for one of Earth's defense ships. The concept is vaguely similar to what one would expect a pre-TOS version of the intrepid to look like with a longer body, and a more catamaran designed nacelle geometry.