and you are left on the pier, alone, to wave forlornly as it recedes into the horizon; indicates that an action or decision has been irrevocably taken and that there is no sense in further attempts to alter it, as in “Don’t bother trying to convince the CMO about the rebrand, that ship has sailed”; stems from the fact that when ships have left port, to return to dock would be laborious and expensive and so is rarely if ever done, much to the chagrin of modern cruise ship passengers who failed to return on time after shore excursions and must now be helicoptered to the vessel if they wish to resume their itinerary