While iNavX is a great tool, I switched to Garmin Bluecharts for our charters. Here are the main reasons why. Some of the reasons may be a couple of years old now, but I’ve been happy and haven’t looked back.

1. Charts are MUCH less expensive on Garmin.
2. Charts are MUCH easier to purchase and download through the App Store versus setting up X-Traverse Maps, downloading the charts, etc.
3. I like the Active Captain integration for Garmin (though you don’t need it as much in the BVI’s with this great TTOL board on your side).
4. I liked being able to plan out my routes and waypoints on my iPad and then easily email them over to my phone. So that way I knew I had a couple of backups to my primary device, which was my iPad with a Nuud waterproof case and RAM mount.

Yes, it all works offline so long as you have a 3G/4G device with the GPS chip in it.

Here is another thread on this topic.

TTOL Navionics versus Bluecharts thread

In that thread, I posted this Garmin promo video if it helps.

Bluecharts mobile promo video