i'll continue sailing about and see what comes of it. in the meantime, however, nigel's quest has come impossible, since i hit a snag with oxbay's liberation. this one's my fault though. i forgot about ewan glover when leaving port royal, and fast travelled straight to my ship, sailing away afterwards. i remembered him later and went to fetch him. surprisingly, he was still in his spot, and the dialogue worked as planned. two anomalies were that he didn't walk up to me to talk, and didn't walk to his ship afterwards, so i'm afraid i got a case of sequence breaking here. and way to set the relevant flags as triggered up to the point that you arrive in bridgetown? i'm in that town at the very moment.
this being said, fast travelling to your ship at that point should be temporarily disabled in the future to avoid this problem.