This is a 19th-century minstrel song by Edward Warden (1860) that was evidently brought aboard ship. Sheet music for the minstrel song can be found in the Brown Digital Repository. The song may have connections to He-back, She-back.
A. G. Gilchrist records this song between several other shanties in the Journal of the Folk-Song Society, Vol. 3, No. 12 (1908).
Another negro chanty, "Tapiocum", (learnt on shipbnoard by a friend from the singing of an old coloured seaman), is of a more cheerful cast. It describes the happy darkies hauling in the cargo "on de lebby" (levy = river embankment or wharf), with a gay chorus of:
"Working on de cotton-boat, ten bob a day, oh,
Pompey, can yo prick upon de banjo"? etc
Oakum is a tarred fiber used especially for sealing gaps in ships.