The Hermes consisted of a saucer section and nacelle, each similar in exterior design to that of a Constitution-class vessel of the 2260s. Its configuration was significantly different, however, as it employed only a single nacelle. (Star Trek II: The Wrath of Khan, Star Trek III: The Search for Spock)
Ships of the class
The Hermes-class starship was a design originally created by Franz Joseph in his Star Fleet Technical Manual. The production staff of The Wrath of Khan and The Search for Spock used some of Joseph's Technical Manual images as plates for background displays on bridge monitor screens.
According to the Star Fleet Technical Manual, the only distinctiveness between Hermes-class scout and her sister class, the Saladin-class destroyer, were her armaments. Where the Saladin-class housed three phaser banks and two photon torpedo launchers, the Hermes scout only housed one bank of two phasers.
Intended to be merely background decoration, freeze frames and close examination have inconclusively shown that the images used were taken from the Joseph book with little or no modification. This would be confirmed later by Rick Sternbach on a few occasions at TrekBBS.com.
The Hermes-class was also present in the Star Fleet Universe series of games.