The center of displacement is always below the center of mass, so the iceberg never gets the stability of a rock hanging on a thread (ships can do that with bal

The center of displacement is always below the center of mass, so the iceberg never gets the stability of a rock hanging on a thread (ships can do that with ballast). The only way for an iceberg to achieve stability is "differential" - every infinitesimal movement needs to move the center of displacement in a way which counters the movement. This basically means flat bottom.