When last I was tending to this thread we were sifting through references to chantying in the 1870s. The discussion by this point has become quite sticky, because even contemporary references from the 1870s are potentially "contaminated" by the available articles from the late '60s. Still, I'll go on with trying to cite activity attributed to the 70s, with the caveat that , for the sake of time, the authenticity of each source is not being verified.

There is a travelogue by Symondson from 1876, TWO YEARS ABAFT THE MAST, that describes his voyage in an English merchant ship SEA QUEEN. Based on the date of the preface (Sept 1876), the voyage must have started in fall of 1874 or earlier. "Chanties" are mentioned by name several times. The term is used in quotes, still suggesting, perhaps, its relative newness.

When attempting to leave London, there's this:

//
Tuesday, at eleven o'clock, the third mate returned aboard, accompanied by Mr H (one of the owners), with instructions from the owners to return to Gravesend. We were not a little amused whilst heaving round the windlass at seeing Mr H leaning over the bulwarks deplorably sick. Our putting back made the men strike up the wellknown homeward-bound "chanty"—

" Good-bye, fare-ye-well;
Good-bye, fare-ye-well!"
//

When this author says "windlass" he means capstan. So it is GOODBYE FARE YOU WELL, which I think is more of a brake windlass chanty, but here we have it for capstan.

Off Portland we have this:

//
We filled up with water and took aboard some fresh meat; and the wind having hauled round to N.E., with fine and clear weather, we weighed anchor to the tune of the "chanty,"—"I served my time in the Black Ball Line,"—and proceeded out by the west entrance of the breakwater.
//

We don't associate BLACKBALL LINE with weighing anchor by capstan today. However, the one prior reference to Blackball Line, from the 1868 "On Shanties" articles, also puts it as a capstan chanty. Weird.

Next, when in Sydney Harbour:

//
Whilst heaving up anchor prior to the tug towing us to the wharf, we had some good "chanties " —for Jack's spirits are at their highest at the thoughts of a run ashore. The "chanty" known under the name of " The Rio Grande" is particularly pretty, the chorus being:—

"Heave away, my bonny boys, we are all bound to Rio.
          Ho ! and heigho!
Come fare ye well, my pretty young girl,
      For we're bound to the Rio Grande."
//

So, RIO GRANDE.

Later while Sydney Harbour is being described generally:

//
As the sun slowly vanishes away, the perspective becomes blue and purple, the sky settles into a bright greenish hue, and the noise and flutter cease, to be replaced by an almost unbroken silence, made all the more noticeable by its suddenness. The plaintive notes of a distant sailor's " chanty " or call alone break upon one's ear at intervals; and sweetly pretty they sound, particularly at such a time and place.
//

Ooh, chanties are still 'plaintive'!

Another general comment -- giving some insight on non-Anglophones knowing chanties:

//
Since the introduction of steam, there has been a large proportion of foreigners in the English merchant service — mostly Germans, Swedes, Dutchmen, and Russian Fins. All foreigners are called " Dutchmen " at sea. However, those who sail out of England on long
voyages, have mostly been so long in our service, that practically they are Englishmen, knowing our "chanties" and sea-rules better than their own.
//

On the difference between Navy and merchant ships, the author reconfirms what we understand to be the case, that chanties were not part of Navy practice:

//
Merchant Jack laughs with contempt as he watches their crew in uniform dress, walking round the windlass, weighing anchor like mechanical dummies. No hearty "chanties" there—no fine chorus ringing with feeling and sentiment, brought out with a sort of despairing wildness, which so often strikes neighbouring landsfolk with the deepest emotion. He likes to growl—and he may, so long as he goes about his work. I have heard mates say—Give me a man that can growl: the more he growls, the more he works. Silence reigns supreme aboard a Queen's ship; no general order is given by word of mouth—the boatswain's whistle takes its place.
//

"Despairing wildness"! Nice.