Routing Dakar to Ascension on a dark old evening the Nav headed for his sextant and started the mantra. Some time later, from the rear of the flight deck, was heard the sound of paper being screwed up and the comment, "Well, that was a waste of f'kin time!". Funny on its own but even funnier hearing it twice more as we followed a wobbly NDB south through the ITCZ.