I never managed to place Roll Jordan (Tree of Life &c&c) in a work environment, land or sea. And I seemed to have lost track of my copy of Grimké but, if memory serves, it's not the same 1988 volume as Gibb's and there was no mention of a pre-war journey to Beaufort or St. Helena.
If one keeps in mind, management sings the verse and labour gets the chorus; the St. Helena Experimenters et al were certainly new management; ergo new repertoire comes with.
Driftier: There was no way in heaven the newly arrived 'Yankees' could understand and transcribe natural Sea Island Creole lyrics. The singers must switch to a greatly simplified colonial English to be understood at all. And if any author writes in a spoken word accent it's very likely deliberate schtick for the benefit of the reader. Good intentions aside, better to think of the Port Royal materials as a kind of imported Christian minstrelsy/Tom Show. 'Based on a true story' &c.