Best bang for the buck, a
refurb Note3 running OCPN. Get two. Raspberry Pi is a good value, as well, with OCPN. A
laptop? Install Ubuntu, kick the WinDOHs habbit, and install OCPN. Did I happen to mention that I like OCPN? It's free, too, and you can't get your
charts "updated" off your
phone. For US waters BTW, you can get free
charts, so the app, charts, and OS are all free. But if you are stuck on WinDOHs, you are still in luck because OCPN can run on that POS OS as well. Don't know about Mack. Won't install on an i-thing even if it is rooted/jailbroke.
CM93 charts will play on OCPN, and most other charts as well. And you can scan paper charts and then georeference them for use in OCPN. You can even convert
Google Earth images for use in OCPN but of course you won't have the navaids or hdrrographic data. Sometimes just knowing where the
water is very pale blue and where it is very dark blue is good enough. Sometimes it isn't. On the Bahama banks you will want the best charts available and even then you are likely to discover an uncharted
coral head the hard way if you aren't careful. I could say "just don't go there" but it is beautiful and a fairly shoal
draft boat just NEEDS to spend some time on the banks.