During the nineteenth century, Bristol, England, was the busiest seaport in the world.
While local sailors were at sea, tradesmen would extend credit to their wives until the very day their husband’s ship returned to port.
Because the ship meant her family’s livelihood, women referred to their husband’s vessel as “my ship”.
And when asking for credit, they would promise to pay the tab “when my ship comes in.”
These days, the expression often means dreaming of better times since the arrival of the figurative ship is not a sure thing.