I just imported all of the RNC charts from NOAA as well.
I'm not sure where you are in the development process on these things but I'll give you my first blush impressions. Don't take them as overly critical, but as a tester we don't file bugs for "this works. ;-) Here goes:
Switching charts (along the bottom of the screen
and the Up and down arrows) to be completely confusing. Stitching is definitely needed and instead of "changing charts" just allow the zoom in and out to change the chart being displayed.
I sometimes found dragging the chart around didn't move the chart.
You might also consider adding a download add-on which will download NOAA charts for you.
Also a "Go to boat" icon is needed as well as in the right click menu.
Keep up the awesome!