A further documentation of the African influence regarding Shanties is noted in the liner notes of an old record I have entitled Whaling and Sailing Songs from the Days of Moby Dick by Paul Clayton (1956). The performance of the songs is a bit weird, but he does seem to have done some research.
Regarding the Shanty Blood Red Roses he notes:
"It is thought that this fine old halyard Shanty is of Scottish origin. It is mentioned by Captain R.C. Adams in his book On Board the Rocket (1879) as being sung by the Negro crew of an American ship in mastheading the maintopsail, but is unquestionably of earlier origin than this mention." Unfortunately he doesn't say where he got the information regarding the Scottish conection.