Oh, here's some more fun, references to "shanty singing" in the 1840's. I've been following up some leads in Bill and Gene Bonyun's book Full Hull and Splendid Passage and this one paid off:

Some Recollections, by Captain Charles P. Low, published by Geo. H. Ellis Co., Boston, US, © 1906 (http://www.archive.org/stream/somerecollection00lowciala/somerecollection00lowciala_djvu.txt)

Commanding the Clipper Ships "Houqua," "Jacob Bell," "Samuel Russell," and "N. B. Palmer." in the China Trade 1847-1873.

Aboard the "Toronto" from Boston to London, circa 1844, p. 35

We had a crew of thirty seamen and four ordinaries, no boys. The crew was made up of the hardest kind of men; they were called "hoosiers," working in New Orleans or Mobile during the winter at stowing ships with cotton, and in the summer sailing in the packet ships. They were all good chantey men; that is, they could all sing at their work and were good natured and could work hard, but they did not care much about the officers and would not be humbugged or hazed. Besides this large crew, we had as steerage passengers twenty men from the ship Coromandel, an East India ship that had come home from a two years' voyage, who were going to London on a spree. The steerage passage cost only "fifteen dollars and find themselves." They were also a jolly set of fellows and when we reefed topsails or made sail they all joined in with us, so that our work was easy and we could reef and hoist all three topsails at once, with a different song for each one. In the dog watch, from six to eight in the evening, they would gather on the forecastle and sing comic songs and negro melodies.

Arriving at the London docks: p. 37

The London docks are all enclosed, and you can only enter at high tide, slack water; and as soon as the ship is in, the gates are shut. It was very late in the evening when we entered, and while hauling in, the two crews united in singing, and made such noise that the dock master requested the mates to stop them, as they would wake up the whole of London. But when the sailors heard this they only sang the louder and only stopped when the ship was made fast.

Loading Cargo: p. 38

We had a great many tons of these cheeses on board as freight. Some weighed one hundred and fifty to two hundred pounds and were very ugly things to handle. The sailors discharged the cargo and hove the sling loads up by a winch at the mainmast. If very heavy we took the load to the capstan; and while we were heaving away, at eleven in the morning, the sailors struck up "Roll and go for that white pitcher, roll and go," and the steward would come up with a great pitcher filled with rum, and give each of us a drink. The same thing was repeated at four in the afternoon. This was varied when we were taking in cargo, which consisted of a great deal of railroad iron and we had to pass it in from a lighter alongside and then down the hold. It was terribly hard work, and instead of the rum, a quart of beer from the tap room was brought to each one at eleven in the morning and four in the afternoon. I do not think we could have held out without it.

Cheerily,
Charley Noble