- Continuous acceleration would provide artificial gravity, but ships would be built like silos, not boats.
- A rotating section is the most feasible explanation for pseudo-gravity, but I've found only a couple of commercially available ship maps that actually have rotating rings.
- A small black hole providing energy at the core of a ship would lead naturally to concentric rings or spheres, with feet pointing toward the center (assuming tidal forces wouldn't rip the crew apart).
- A moon-sized ship would have spherical decks, albeit with a huge area.
Yet all spaceship deck plans I've seen assume the crew stands perpendicular to the direction of motion, on the same plane ... as if the ship were a set built on a studio backlot.