Many sailors with modern radar have spent installed MARPA (Mini Automatic Radar Plotting Aid). The radar acquires a target and in a short while deduces its course, speed and likely closest point of approach. Unfortunately, results are often disappointing. Nothing is finalised yet, but the emerging truth is that this is because most small-craft operators use MARPA with the radar in ‘head-up’ mode. In this format, many radars do not actively link to the electronic compass system and MARPA doesn’t like it. In some cases at least, it has been shown that with the radar in ‘north-up’, or even better, ‘course-up’, the compass comes into play and the MARPA makes a much better fist of behaving itself.