Not P but Moby-Dick (29)

[Mike Jing]

>From Chapter 48:

“Pull, pull, my fine hearts-alive; pull, my children; pull, my little
ones,” drawlingly and soothingly sighed Stubb to his crew, some of whom
still showed signs of uneasiness. “Why don’t you break your backbones, my
boys? What is it you stare at? Those chaps in yonder boat? Tut! They are
only five more hands come to help us—never mind from where—the more the
merrier. Pull, then, do pull; never mind the brimstone—devils are good
fellows enough. So, so; there you are now; that’s the stroke for a thousand
pounds; that’s the stroke to sweep the stakes! Hurrah for the gold cup of
sperm oil, my heroes! Three cheers, men—all hearts alive! Easy, easy; don’t
be in a hurry—don’t be in a hurry.

According to the OED, "heart alive" is an exclamation. What is the meaning
of "my fine hearts-alive" and "all hearts alive" here?