Usually only the program has to be installed on the "hard drive", usually data like chart data can be on a chip with another drive name other than C.
That thing I gave you the link for can take a huge hard drive, power it and make it's data available over wifi
for up to five devices simultaneously, good for storing movies, music
, huge numbers of photos etc. Open CPN
would probably allow you to have the chart data on a file there, but I've not tried it. I've got Garmin
blue chart which I like and Navionics
which I like less, but Open CPN
works so well, and is so well priced, I think it's my new favorite. I've set up two Motion LE-1600's for it, one as a back-up, really great, but old tablet that you can get on Fleabay for around $100. I put a SSD in my primary one.
I'm just learning
Open CPN and have not used it's advanced features yet
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