(idiomatic) To either improve one's behavior or else be required to leave; to either improve one's performance in an activity or else withdraw from that activity completely.

Alternative form of spoil the ship for a ha'p'orth of tar

(idiomatic) When one makes a significant amount of money. / (idiomatic) When one is successful

Alternative form of that ship has sailed

To have something important fail for want of a small amount of money or effort.

A leader is ultimately responsible for the penalities of a catastrophe, even they result from external causes or the misactions of others under his purview.

(simile) Quickly but futilely, away from a failing project.

(New England, nautical, idiomatic) Said of an unwisely or overly extravagant person.

Alternative form of ships that pass in the night

(simile) Two or more people who encounter one another in a transitory, incidental manner and whose relationship is without lasting significance; two or more people who almost encounter one another, but do not do so.