I've found another great source to consider re: the "genesis of chanteys" topic. I don't seem to remember it being discussed before.

It is fiction, and the date is 1869, so there is that possibility it was drawn from elsewhere. But whatever the case, the material is great.

THE ARK OF ELM ISLAND by Elijah Kellogg

The narrator keeps remarking on Black people's tendency to sing as they work. "...a nigger can no more work without a song, than a Frenchman can talk if you tie his hands."

The Ark has a crew of "Portland [Maine] darkies," and amongst them is a "chanty-man" named Isaiah Phillips.

The work songs, "habe no merit of composition, being the merest trash."

"The songs of the negro seamen generally refer to their labor-- hoisting or stowing molasses, or screwing cotton, which is severe labor, where unity of effort is of the first importance; and here the negro's accurate ear renders them most effective, and they will accomplish more, with less fatigue to themselves, than white men....they will put in the queerest quirks and quavers, but all in time."

An anecdote is told, during which a work song is quoted -- a variant of what Hugill called "Hooker John":

"Eberybody he lub someting
    Hoojun, John, a hoojun
Song he set de heart a beating
    Hoojun, John, a hoojun"

That's the first reference I recall seeing to that chantey. Usually people take Hugill's text and start speculating what "hooker" is. (I myself have speculated it was "hoosier.")

The narrator mentions ad-libbing.

The crew was manning the windlass, and "Isaiah" sings, intriguingly, what is obviously a variation of "Stormalong":

"Wind blow from de mountain cool
    O, stow me long
Mudder send me to de school
    Stow me long, stow me"
[etc -- more, completely incidental verses]

Later, the cook songs a song, just for joy. It is none other than one of my favourite chanties, "Hilo, boys, a hilo."

Then the workers "struck up a still quicker tune, intermingling with the words most singular yells and quavers."

They thn haul out with a hand over hand chantey that I don't recognize, with a chorus of "Hand ober hand, O"

THEN they walk away with the rope. The song quoted os another "Fire down below," yet one that looks like it could have been "The Sailor Fireman" cited by Hugill.

Much later in the story, while not at work, someone sings "Highland laddie" (pg 255).

Interesting that nowhere are the songs referred to as "shanties/chanties," although, as in Nordhoff, "chanty-man" is referred to (twice). It is after Clarke mentioned "chanty-man" in 1867, and before Alden finally says "shanties" in 1869.

The passage starts around pg 117