Starbuck and Stubb manage to retie and hoist some of the sails, and the ship begins to move in its normal direction, roughly eastward, despite the storm. Starbuck goes down to Ahab’s cabin to inform him that the ship is now moving, but outside Ahab’s door, Starbuck sees a loaded musket, and debates openly whether he shouldn’t simply shoot the captain and take over command of the ship. Although Starbuck knows that to kill is evil, he wonders whether it is not ethically preferable to kill Ahab and save the rest of the crew from certain doom. But, at the last moment, Starbuck lowers the “death tube” of the musket and puts it back—he does not have the heart, or the mind, to kill Ahab while the man sleeps. Starbuck tells Stubb to go down and wake Ahab with the news of the ship’s eastward progress.
In this chapter the conflict between Starbuck and Ahab comes to a head. It is significant that it does so while Ahab is sleeping, as it reveals that the true conflict here is not between Ahab and Starbuck but between Starbuck and himself. Starbuck is a moral man, and he reasons about his possible murder of Ahab and mutiny in morals terms—weighing the life of one man versus the lives of many. Yet within that moral reasoning is also a question of conviction or willingness to act boldly, and Starbuck's moralizing ultimately comes to be connected with a lack of will, a lack of exactly that over-riding sense of self that allows Ahab to discard social and moral conventions and which makes him so powerful. It is also worth noting the parallels between this scene and two scenes in separate Shakespeare plays. IN the first, Macbeth questions whether he can kill the sleeping Duncan. He ultimately does, with devastating effects. In the other, Hamlet contemplates killing the praying Claudius. He ultimately doesn't, with devastating effects. So there is also an element of fate at play here, and it may very well be that no matter what Starbuck decided in this moment it would turn out badly. But as with everything in Moby Dick, there's no way to know.