Ships don't have a mathematical requirement that their internal structure be one homogenous material, thus it's a trivial matter to put a weight at the lowest p

Ships don't have a mathematical requirement that their internal structure be one homogenous material, thus it's a trivial matter to put a weight at the lowest point of the ship so that it acts like a weeble: http://en.wikipedia.org/wiki/Weeble http://en.wikipedia.org/wiki/Weeble