Despite having a bunch of fun Navionics on board, I am a firm believer in having paper charts. Unfortunately, depending on how you approach the problem, they can be ungodly expensive for a complete chart set for your crusing area.
One solution I have come up with for providing me with the paper-based backup that I crave for the Caribbean is the Caribbean Chart Pack from NV Charts. At $179 for the pack, I think it’s a pretty good deal. Check it out. I hope it helps.