Yet another idea: if a ship's motors fail, have a ship ready that can push it in the right direction, in time. Probably need 2x the amount of horsepowers to make up for lost time, but it's not impossible.
Yes, that's called a tug and in plenty of harbors a vessel of this size would not be permitted to do close quarters maneuvers without the mandatory assistance of one, or in this case more likely two, tug boats of a certain minimum size relative to the size of the vessel.