So much for any argument about the "Enterprise is too big to be constructed -on- Earth" ...
We've got vessels today which are larger and more massive than the NCC-1701. Using future technologies and materials, one would assume it would be even easier to construct "starships" comparitively to our seagoing vessels of today.
Far from it.
Naval vessels don't fly and are supported by the sea itself. They are constructed under a proportional ratio that has been used since the times of antiquity. Unsupported some of those vessels would snap in two should an exceptionally tall wave crest under them.
Like this:
http://twentytwowords.com/2013/06/19/large-cargo-ship-snaps-in-two-in-rough-seas-both-pieces-remain-afloat-5-pics/It's not as simple as a diagram. You have to build differently for such large structures to support their own weight in gravity.
NOTE: The Star Trek The Next Generation Technical Manual.
After a Saucer Separated Landing:
"It is assumed that the vehicle would be a total loss insofar as ever being returned to operational service, due to the extreme loads placed upon it, which would result in deep unrecoverable alloy damage."
Special note on page 23:
"Fairly early on, Rick did a drawing for our writers showing the Enterprise superimposed over a map of the Paramount Studios lot. This was fun because it gave us for the first time a concrete idea of how big the ship "really" is. A bit later, though, we started to think of some of the implications of this enormous size. We began to realize that it would be pretty difficult for a structure that size to maintain its rigidity and form, especially under the tremendous accelerations that impulse and warp drive would likely entail. (We envisioned the main impulse engines firing, squashing the ship like a partially deflated blimp."
Page 19:
Without the structural integrity field, the vehicle would be unable to withstand accelerations greater than 7.4 m/sec2 without significant deformation, or greater than 19.5 m/sec 2 without unrecoverable structural damage (in other words, the spacecraft would sag under its own weight in Earth's gravity without the reinforcement of the SIF.
@ Joshmaul
I commented on a PotD recently about "Every Starship is a Planetary Assault ship."
(FYI. ) The Galaxy Class Starship carries enough antimatter to destroy the Earth 35 times over. Just a quarter sized amount of anti-matter could propel the Space Shuttle into orbit!
Any accident would be immediately fatal to entire cities and continents if not the planet itself. That's why in Star Trek IV and DS9 they elude to Fusion plants and Solar power as primary energy sources.