Joanna Colcord, from a seafaring family, had the same question when she published the song. She didn't even speculate on what it might mean.
I know of only two other authentic texts. (The "English" version sung by A. L. Lloyd looks like Lloyd's rewrite of the American song.)
The stanzas appearing in A. H. Verrill's "The Real Story of the Whaler" (1916) do not include the compass reference.
But the version found by Gale Huntington in an 1859 logbook does include it.
Presumably the original has been jumbled. "Four and four" is a great guess. It's a "minor" verbal change, and it makes good sense!