I'm working on plotting my course, using sea charts as well as land maps, and jet navigation charts. One of my tasks is to break the 200+ mile journey down into manageable sections, each with its own navigational problems. I'm constantly checking my data to be sure I'm not building problems into the expedition from the start. I calculate my data by hand, and enter it into my computer and GPS, and verify the results. The image above is one of my recent navigation sheets, marked up as I found errors! Better here, though, than out on the ice.