I'll look at the book again but I think it's 3 decks with 2 zoomed in drawings of sections of the deck to show more detail.
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Quite right -- I stand corrected!
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This is again the problem with trying to base size off of the film, the script, sets, photos, etc. We see lots of differences all over the place. To me, with those windows, I still don't see how you could squeeze more than 4 floors in and that is only if they're stacked with nothing in between like vents and conduits for wires and such which I don't think is the case.
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That's just the thing ... as we established from this picture, the viewport is the full deck high, from floor to ceiling (or deck sole to deck head, if you like). Looking at the various people inside, it even seems the ceiling height at the view ports is a bit over standard (makes sense, as the Bridge has a bit of a theatre structure, with tiered seating):
If I go from this picture posted earlier and draw lines from the viewport to the vanishing point, I can see that I can easily fit 17 full iterations of the viewport over the total height of the main hull, meaning that I can fit my nine decks, with
at least one full deck's worth of space between each:
Just to ensure a second opinion -- if we use this side elevation from one of Graham's blueprints (n.b. that it in itself is a compromise, as each of the three different models depicting the bow section yield somewhat different proportions), then I get 16 full iterations of the viewport height over the main hull:
So, on the whole ... nine decks work for me, I'd have to say.