Apparently Navionics is not meant to be hooked up live unless you have a particular brand of chart plotter (and that is a guess).

I think that if I find out the format that the program writes to the cards, I may be able to use it somehow. Sometimes with these various "proprietary" data formats just changing the extension is enough to fool the software into reading it.

I'll try saving some plots and courses on the garman data card and see if the Navionics might read it, and vice versa. Just means trial and error.