A contemporaneous reference to rowing song style in Sierra Leone, West Africa. 1834.

"But from each and all proceeded the rower's song. No negro spins his canoe through the water without a melody, and, if he be not alone, without the long wild chorus. All sing; and on the rivers of these glowing climes, where all is genial and laughing, as the song breaks upon his ear, the traveller forgets to be a critic. The voices may be harsh when near, the words uncouth, the artists terrible to look upon, the music startling from contempt of all artificial rule ; but, as the simple cadence comes floating over the water, and the strong chorus is mellowed by distance, when the unities of time and place are remembered, there is something inexpressibly affecting in the strange song; at least I found it so.

...

The words of these songs are generally extempore. My captain interpreted several for me. The prevailing subjects were love and irony; occasionally, as will be seen in the sequel, revenge and war formed the theme. A stanza is sung in a loud sostenuto recitative by a single voice ; and at its conclusion the whole crew rush into a stormy chorus, at the same instant springing at their oars with renewed vigour. Several of their effusions amused themselves highly; and, as the extempore verse concluded with some pungent and unexpected idea, shouts of laughter delayed their chorus."

THE WHITE MAN'S GRAVE (1836), by FH Rankin.pp199-201.