Originally Posted by I-Am-Zim
We don't know that Uhura was in the secondary hull. If you'll watch that scene, Kirk and McCoy leave sick bay and go directly out the door to a computer terminal. Kirk locates Uhura and they both run from the terminal straight down the corridor to the room with the big tanks where uhura is. I will have to watch it again to be sure, but I don't think there was a cut in that scene. Therefore, the room Uhura was in was on the same deck as sick bay.
It was my impression based on the size of the room that she was in, and the general look was much more consistant with engineering, which is in the secondary hull.