The idea of variability and improvisation is there:

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The airs to which the chanties are sung are pretty much common property—that is to say, you will hear thom all the world over. Miss Smith has scored many of them, and musical readers cannot do better than consult her pages if they want to test the quality of Jack's music. But the words of the chanties vary very much. There is a sort of general range of subject for each air, while a great amount of latitude is exercised by the chanty-man. In fact, a clever "improvisatore" who can adapt the lives and the peculiarities of officers and crew to the metre of the chanty he is leading, is very much esteemed. Like everybody else, Jack enjoys hearing the foibles of his fellows humorously hit off. and he does not object to being "dressed" a bit himself in turn.

Thus, then, the words of a chanty may be altered according to the ability of the chantyman and the opportunity afforded by the incidents and personages of each separate voyage. All that is wanted is that hauling chanties shall be short and lively; that windlass chanties be more measured; that pumping chanties be adapted to the monotonous movement of the work, and that capstan chanties be in long metre, and of a more tender character in general. Thus it is, that in the capstan chanties, when the men run round and round from slow to quick as the anchor comes "home," we find usually both more sentiment, and more of the semblance of part-songs.

Here is one capstan chanty:

To the Liverpool Docks we'll did adieu,
To Suke, and Sally, and Polly, too;
The anchor's weighed, the sails unfurled,
We are bound to cross the watery world.
Hurrah, we're outward bound!
Hurrah, we're outward bound!

The first four lines may be either sung as a solo, with the last two in chorus, or the four lines by divisions of the men, and the last two in unison. Of course, for "Liverpool Docks" will be substituted the name of any other place from which the ship is parting.
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This OUTWARD AND HOMEWARD BOUND evidently comes from the 1869 Chambers's Journal article. It is verbatim. Smith had another version of the shanty, w/ Catherine's Dock, which probably led the author here to his/her idea about substitution.