We use Navionics on Android phone and tablet -- it is outstanding!
BlueChart is no longer available from Garmin. It has been replaced by ActiveCaptain which is nice if you have a recent Garmin chartplotter with current maps. If not, it is VERY pricey to get the maps and useless without it. You can still access the crowd sourced ActiveCaptain data through a web based interface, but only when you have an internet connection..
1975 Trojan F36 Convertible, Twin Chrysler 440's
2014 West Marine AL360 Inflatable, 1966 Mercury 6HP, 1992 Mercury 20HP