For a three-act plot analysis, put on your screenwriter’s hat. Moviemakers know the formula well: at the end of Act One, the main character is drawn in completely to a conflict. During Act Two, she is farthest away from her goals. At the end of Act Three, the story is resolved.
Act I
Ishmael decides to go on a whaling voyage, travels to Nantucket, and finds a BFF, Queequeg, and a ship, the Pequod.
Act II
After learning of Captain Ahab’s quest for revenge on Moby Dick, Ishmael continues to be a part of the day-to-day whaling activities of the Pequod, explaining many (many, many) of the technical details of whaling to the reader.
Act III
The Pequod discovers and pursues Moby Dick, but the ship is destroyed in the process and everyone except Ishmael is killed.