Yeah, Daze and Cranberry, that is what I drew here in pencil myself here seems like days ago now lol. I tried to get it into Paint or Photoshop, but as mediocre as my skills are I could not convert the image and overlap and do all those steps you so easily just did, so thanks!
So based on that I think that "during" the storm Hoban could not or would not be running around rushing to plot a "during a storm" location. He was seen all around on deck mostly sulking, so I think he made the ones prior to the re-route to Krawk Island and the others had to be made by someone else. It almost doesn't matter but I suspect Anshu or Captain/Shumi, in other words someone in charge or someone documenting a course that planned to alter it in the first place (Anshu's motive, though somehow I do not suspect him the "criminal" for some reason).
EDIT: Okay, you guys did extrapolate a little further. I am not so sure that is the intention of the map, and I don't think the ship's course is meant to indicate where Hoban is now, but I could be way wrong. Hmmm.
Yeah, something about that doesn't make sense. If they already went to KI and Hoban drifted toward where they are now on MI, wouldn't they have hopefully seen him? Or has the whodunnit gone too far now? The multiple choice crude nature of this drives me mad, lol. I think the last X on the grid is where the ship was last, just before they landed where they are now. Where we are now (in the plot).