Interior shells of plasma-charged atmospheres are quite common; water
less so. Assuming we are not discussing aquatic entities it is more
likely the water doughnut appeared as liquid, but was in fact another
state of matter entirely.
A torus of energy amortises all inertia effects in many
near-terrestrial designs, helping to integrate everything inside the
shell of the craft within a single field.
The grid system of navigation is equally applicable to all spheres -
indeed, the terrestrial 360 degree grid of nautical miles is a
derivation of such a system. The electromagnetic fields on Earth have
been altered to more closely follow this system for both navigational
and propulsive purposes below the ionosphere.
Does this help? Any more descriptions would be useful.