Thanks for this all - fascinating reading. I can't help wondering if there might not be some connection with waulkin' songs - sung while kneading tweed cloth soaked in urine. The tempo and gait is similar to, for example, Waulin o the Fauld (Western Isles), which would work just as well for rowin' to as for waulkin'. One could imagine men using the tune for the one purpose, and women for the other!

Strange that I should have learned what turns out to be a composite of the two sets of lyrics - but then that's folk music for you!