What are some purposes and effects of Chapter 23 ("The Lee Shore") of Herman Melville's Moby-Dick?

Chapter 23 (“The Lee Shore”) of Herman Melville’s novel
Moby-Dick has a number of different purposes and effects, including
the following:

• By opening by referring to an
  earlier section of the novel, this chapter helps contribute to the unity of the
  book.


• By referring to the Pequod’s “vindictive bows,”
  this chapter helps foreshadow and highlight a major theme of the novel:
  vengeance.


• By referring to the “cold malicious waves” of
  the sea, this chapter helps remind us that all ocean voyages during Melville’s day were
  inherently dangerous. This was particularly true of the extended voyaging of whale
  ships, as when Ishmael mentions here a “four-years’ dangerous
  voyage.”


• By saying that he looked upon Bulkington with
  “fearfulness,” Ishmael foreshadows Bulkington’s fate and at the same time characterizes
  himself as a man of sympathy and common sense: he is not stupidly
  brave.


• By saying that he offers this chapter as a
  “stoneless grave” for Bulkington, Ishamel indicates that at least one man – perhaps more
  – will die as a result of this voyage. His intention to commemorate Bulkington shows
  Ishmael’s own decency and concern for other people. The foreshadowing of Bulkington’s
  death already contributes to the tragic tone of the
  book.


• By referring to the forthcoming voyage of the
  Pequod as a “tempestuous term,” Ishmael hints that the voyage will not be an easy
  one.


• By characterizing Bulkington as a man ever in
  pursuit of goals besides comfort, Ishmael implies his admiration of the bravery of
  whale-men in general and thereby also implicitly characterizes
  himself as a brave man.


• By
  describing a ship as rushing

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for refuge's sake forlornly . . . into peril; her
only friend her bitterest
foe!

Ishmael reveals his
taste for paradox and his appreciation of the complexities of life.  Ishmael is not a
simplistic thinker, as passages such as this already
imply.

• By directly addressing the reader (as
  when he asks, “Know ye, now, Bulkington?”), Ishamel engages in a kind of conversation
  with the reader, making the tone of the book more intimate and literally
  dialogical.


• At one point Ishmael declares that
  

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all deep, earnest thinking is but the intrepid
effort of the soul to keep the open independence of her sea; while the wildest winds of
heaven and earth conspire to cast her on the treacherous, slavish
shore?

By expressing
admiration for such thinking, he thereby characterizes himself as an intrepid soul
intent on keeping his independence and avoiding slavishness.  It remains to be seen
whether Captain Ahab will also emerge as such a person. In any case, this passage
foreshadows a major theme of the novel: life itself as a kind of metaphorical
voyage.

• By declaring his admiration for people
  who take brave risks rather than living merely comfortable lives, Ishmael raises a major
  question posed by the book: should Ahab be seen as such a person, or is he something
  else, something smaller?