I recently used EARTHNC.com charting to make a trip from Tampa, Fl to the
Dry Tortugas and back. Admittedly not an intinsically difficult trip
navigation wise but a chance to use this Android App in a limited
offshore trip. It makes your android
phone into a
chartplotter. It worked as advertised! While in Cel range of shore all NOAA raster
charts are available and you can zoom in or out as your needs dictate and movement from one charted page to the next is seamless. Once out of range the app uses the
phone GPS to accurately plot your position on any
previously loaded charts you have in
storage pretty nifty! Of course I used a regular
GPS and paper charts as well but the phone was never wrong . You do have to download the charts for your trip but it is easy enough.. cost me 10.99 a year subsciption for
Iphone or android...Good Luck