Okay, I still don't think Melville knew what a narrative structure was.
I'm up to chapter 43 or so, still listening on audio provided by Librovox. The story is all over the place. There is an entire chapter dedicated to "cetology," the study of whales, where the narrator classifies and lists everything he knows about whales. That simply has to be the most boring chapter in the whole book, completely escaping the narrative. The only thing it might be able to provide is a kind of realness to the whaling background.
The problem is that I could never get this far just reading it myself.
And then it finally gets a bit interesting.
Captain Ahab finally comes out of the cabin. This has to be a great star part, much like Orson Welles in The Third Man.