Cincinnati Daily Gazette (June 24, 1867), p. 1:

"On shipboard, all is quiet, excepting when sail is made or shortened, or the tack is changed. Then, however, there is noise indeed.

"The sailors rush like mad for the rope to be pulled, and some lusty-lunged fellow strikes the time with [a] loud discordant 'Yo, heave, yo!' or some weird tune ending in a chorus 'of Ranzo, boys, Ranzo!' or 'Shallow, shallow Brown,' and all pull together."

We've seen the word "weird" before, applied to chantey tunes in early reports.

It suggests just how far outside the mainstream of parlor or concert music the chantey tunes seemed to be.