The word "rouster" was pronounced "rooster."

A little more information from "The Mississippi Roustabout," Stoughton Cooley, The New England Magazine, v. 17, issue 3, Nov. 1894, pp. 290-301.
"The sense of rhythm in the roustabouts, like that of all Negroes, is very acute. Though they have a limited vocabulary, they readily construct songs for any and all occasions. Whether it be at a log freight pile---or leaving port at New Orleans, where the crew line the forecastle and sing as the flag comes down, the words will be apt and the tune melodious. No boat ever had a name so long or so outlandish that they could not weave it into a song; no event in river history is so complicated that it cannot be told in musical rhyme.
All of the songs consist of rhyming couplets, with a refrain following each line,- the leader lining off---, the whole crew.... joining in the chorus. The sense of rhythm shows itself even in their walk. They have a swinging, shuffling gait, called "coongineing," in which their movements are in such accord that the whole boat will respond, swaying until the mate compels them to break step."
The men may be divided into watches, each with a "captain of the watch."