Before jumping on me, SEAiq USA cartography IS the paper charts, just presented on a screen. Aqua Maps and Navionics charts are updated constantly. Navionics displays Active Captain only, but has an auto routing feature that I have found useful. Aqua Maps displays both Active Captain and Waterway Guides information. Aqua Maps and Navionics both have proprietary cartography and highly accurate depth information, tide and current information. SEAiq USA gives me paper charts on a screen that change scale as they are zoomed in or out. The apps I use are Aqua Maps, Navionics, and SEAiq USA. It can supply position information for up to five devices simultaneously. The GPS flaw hasn’t really affected me because I use a Dual 160 Bluetooth GPS for position. In fact, I carry two, one primary, one backup, one cell enabled, one not. I use an iPad Pro 12.9” because I like the large display. A caveat for using iPad for navigation apps- the iPad Pro 12.9” cell enabled models have a flaw such that the native GPS is not reliable.