oh but you could...
Please explain?
The ship would need sleeping quarters for 80 officers and crew. That would mean most of the saucer section would be taken up by their rooms, even if they were sleeping 4 to a cubicle such as the areas seen on DS9 of the Defiant. The engineroom seen in "Pegasus" was two decks tall, which would require either of these two options to be true:
1. The secondary hull is accessible easily by way of turbolift or stairs. This would be required since the primary hull could not contain the bridge (1 deck), engineering (2 decks), the computer core (2 or 3 decks) and the living quarters. Not to mention all the myriad science areas and other rooms aboard a normal starship.
2. The length would be over twice that of the stated number of 120 m, and instead would be closer to 300 m. This would allow all of the above-mentioned areas to be contained within the saucer section, and the lower section used only for equipment decks and such.
Of course, the second option is fine, since we could possibly presume that there are a number of different size configurations for a vessel of this type, much like B'Rel and K'Vort BoPs.
Any way you look at it, of course, the Oberth is a nifty little ship. It seems to fit nicely with the rest of the fleet of the era, yet is small enough to be a scout and science vessel in its primary function.
