LitCharts assigns a color and icon to each theme in Moby-Dick, which you can use to track the themes throughout the work.
Limits of Knowledge
Fate and Free Will
Nature and Man
Race, Fellowship, and Enslavement
Madness
Religion
Summary
Analysis
Ahab awakes the next morning to find that the compass needles of the ship have been turned around by the electrical energy of the storm, and that the Pequod is going west, instead of east along the equator.
Another means of steering the ship has gone by the wayside, indicating that the ship travels Ahab's course, or perhaps fate's course, toward its showdown with Moby.