We use our ipad all of the time for this. We have a Garmin
plotter as well, but sailing up into Canada this summer it lacked cartography. I would recommend it to anyone as a backup, or if you are taking a trip somewhere where you don't yet have charts
. The Navionics
apps are cheap and the iphone versions will run (and are even cheaper, though lower resolution). iNavX has it's problems and I can't recommend it. I really wish I could get a refund, both for the app and the international charts
from Fugawi. The charts
are essentially rentals with a time out on the time you can download them, so if you ever need to restore your ipad later you are SOL.