Fog ships basically are starships; it's just that they can also swim. Even canonically, Iona's ability to dive works by gravity manipulation, not buoyancy control and hydrodynamics, and her main propulsion appears to be some sort of plasma drive. Fog ships are submersible even when they're patterned after ships that patently weren't (e.g., Takao), they can fly, and in the manga there's at least one that can teleport interoceanic distances.

That said, their ship configurations can be altered, and internal mechanisms reconfigured. I-400-class Fog submarines were not normally equipped with supergraviton cannons, for instance; Iona cannibalized hers from the wreck of Hyūga.

Also, and on a point of order, at the moment he has a girl and seven kilotons of metallic dust (and the latter is at the bottom of an antarctic fjord, to boot), not a submarine. :)

--G.
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Benjamin D. Hutchins, Co-Founder, Editor-in-Chief, & Forum Mod
Eyrie Productions, Unlimited http://www.eyrie-productions.com/
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