SUCKS SUCKS SUCKS, after they charge you,,, you will use this app successfully,,,,then randomly when you are counting on it working so you can navigate in unfamiliar waters well outside of internet or cell coverage.....it will will tell you you need to "sign in".......(normally the app just opens up like every other app but NO......now I got to "sign in?".......good luck with that!!! It won't work without cell coverage,,,,,"you can download charts" they say,,,, No cell coverage? not gonna work!