Its not like a fin, what is it officially called? I have no idea myself.
What is the forward skeletal bulbous section under the Nebulon-B Frigate called?
Which bit exactly?
Well it was kitbashed from model ship hulls glued together so I say we refer to it as "the hull."
The bottom of that main prow-pylon is the main weapon mounting too. The rod looking doo-hicks are huge cannon thingies.
i have been pouring though the deck plans, and they never describe it, but it holds all the important things, it seems.
There are lots of names that spring to mind, sadly none that are repeatable on a family friendly website 
....you're welcome.
Edited by FTS Geckoi have been pouring though the deck plans, and they never describe it, but it holds all the important things, it seems.
Yeah, the hull.
Edited by SanchezI've heard it called the ship's chin, likewise on the assault frigate and other ships that have a similar structure.
If it were dorsal instead of ventral I'd call it a superstructure. Substructure, maybe?
The Taint
I called it lots of names when I was building my Neb B, none of which can be repeated here! Keel seemed to stick in my mind though and for the lack of any other useful term that's probably the tag I will give it when playing
Edited by bulldogukSorry FTS Gecko, that does not help at all.
Thank you Bulldoguk and Levi Porphyrogenitus.
Superstructure and Keel both seem to work, just need to think of what would be better.
It's posts like these that make me love these forums. I mean that with all honesty.
I always wondered why you would design a starship intended for combat with such a tiny, spindly mid section. It's just asking to be blown in half by a well-aimed torpedo. Plus structural stress etc etc. I know someone in 1977 saw an outboard motor and said to themselves "wouldn't it be fun if there was a spaceship like that" but seriously. Especially since the other large ships actually make sense, e.g. Star Destroyer, Corvette, even the Millennium Falcon would work as an actual physical spacecraft. But the instant the Nebulon-B tries to turn while accelerating, it's going to snap in two.
*Disclaimer*
Yes I know Star Wars doesn't do real physics. Just my engineering brain.