Hmmmm, I just went through a discussion about the various Navionics offerings on the BBC site. On my Android phone, I have the Navionics Boating app. Costs between $5.00 and $15.00 per year. I don't remember exactly.
I asked if I should buy the "Chip" for my Humminbird 587 ci hd AND if that chip will give me better detail compared to my Navionics phone app. I was told that the phone app has the exact same data and presentation (other than size, obviously) as does the chip.
I decided to give the phone a more thorough workover. I bought an extended mount for my phone to bring it closer to my face. I am considering making a "shade" to give it more clarity in the sun.
Just FYI richg99
p.s. I am here in Houston TX. I have used the Nav.app on a Texas lake in the past week. I just dialed up Chick. I can see pretty fine depth readings in Harrison Bay on the same installed free map. FYI