Steve, you need to find the previous threads on this topic. My internet is playing up and lucky this is getting through. The relief maps need to be downloaded on your phone as the GPS units don't have the processing power or storage to do it all. You then have to use WiFi to get the maps across to the unit. Good luck.
Sam
Try this post
http://www.ausfish.com.au/vforum/sho...Relief+shading