Ah, that's THE quotation. Nice to see it in full here. I like to think of that as the earliest English chanty as opposed to the Gulf chanties.
And we know this is real stuff because there are plenty of later versions and quotes.

Spunyard and Blowhard, yes hokum, but definitely a solid part of writers about maritime as used extensively by Dibdin and his contemporaries and imitated later. it has the dual purpose here of using expected generic names and keeping the real participants anonymous.