a shanty or chantey is a work song with a word or two which is shouted out. This is what keeps the men hauling together. to me way hey ... HUH! we'll pay Paddy Doyle for his boots.
a forebitter or a foc'sle (forecastle) song is entertainment. Songs like Rolling Home are Homeward Bound songs.
There were no engines in the old days to do the heavy lifting, just "Norwiegen Steam" (muscle power) and, without a rythym they would all be hauling to their own beat.