The Third Dimension

I use a few constants in my plans which deserve a little explanation.
The thickness of the walls is almost always 30cms. This is because The Empire Strikes Back provided a highly unusual piece of hard data concerning the thickness of the walls of the Falcon, by virtue of the Falcon's ring corridor has been physically cut into at one point, and the exposed slice through it is visible is a few shots. I have adopted this as a standard except where irreconcilable factors dictate a thinner wall, or the curvature of the hull dictate a thicker one.

The deck / deckheads of ships is set at 50cms with the habitable head height being a standard 250cms. This is an international standard adopted by virtually every vehicle manufacturer who intends for their product to be used globally. NASA, Boeing and Vosper all use it for example, as do many architectural firms. The 50cm floor represents space for structural support, support for whatever may be expected to stand on it, and the wide variety of plumbing, ducting, electrical and miscellaneous equipment that needs to traverse the entire ship.
This defines a 300cm section to provide habitable environs on a ship.

After creating the spruced plan elevation of a ship, the next thing I do is to determine what areas of that ship are likely to be able to include the 300cm sections. Often this is fairly obvious, many couriers exceed this measurement by some way, though not enough to justify two decks. When it isn't all that obvious, I can do a few things to determine the habitable zone. Firstly, I can simply do a side elevation, and if necessary a front or rear elevation. I say simply, often these take far more time and effort than the deckplan itself. Secondly in situations where even this could prove to be ambiguous, I build the ship in LightWave 8, which then allows me to slice and dice a three dimensional model into its 300cm deck zones. This also allows me to render the slices directly, giving very precise footprints for the plan.

In several cases there are places on maps where the head height is greater or lesser than the 300cm. Most of the time this would include things like the autochef being situated in a sloping section of the hull, so towards the rear of the unit, head height is definitely not attained. In every case where this would represent any kind of serious impediment to movement, it is so noted on the plans.

I work on the assumption that most people on a ship will be quite able to navigate around minor obstructions with no difficulty, and so momentary drops in height are not recorded. This is consistent with the deckplan standards on modern vehicles.

One final point on this issue is I will not be bothering to make notations of any changes in this 300cm standard. What I mean by this is if a person looks at a ship which is created for, for example, the Ssi'ruuk then I assume that the person will make the logical leap that the deckheads will be a lot higher on their own. I don't feel the need to mollycoddle to that extent.