I;m with Harvey on this one. Shanties particularly have a rhythm which is mean to match the work being done. It comes as quite a surprise when you are soloing at stamp-and-go rate and you find the chorus is being sung at capstan or downton pump speed. I have a theory that its doen to let the chorus joiners have as much of the song as possible but I'm still going to sing "Slowing down to Lethargy" at a rollicking pace to show up the irony :D