These ships are built like subs (only vertically oriented). Not like surface ships, and especially not like Orbital Shuttles and Aircraft. That is how we can determine their mass. Just find submarine (surfaced displacement = mass, submerged displacemet depends on volume only) size (length) equivalents, and consider that subs are on average 8-12X longer than wide, while expanse ships 3-4X higher than wide. And that, for both subs and expanse ships cases, is due to design limitations by functionality.
