iNavX and associated charts can control your boats autopilot. Navionics app can't, but if using primarily as a good planner and back up, both are good. Navionics, on an around the world trip would work out cheaper.
Put Navionics HD on my Ipad 2 yesterday and wow! It is full screen, touch screen with every thing else you can think of. On of the best 34.99 i have spent. Only thing I have to figure out is how to mount it at the helm. Any ideas?
Have a look at 'gumdrop marine series'. They have a number of support brackets available also.