GPS and electronic charts question?
I used to ask myself these same questions until I started smoking through the ears from frustration.
Finally found a FREE full-featured nav program call SOB (www.digiboat.com.au).
Uses c-map charts, either on CD or the NT+ cartridges from a plotter. You''d probably only need one or two c-map cartridges for all your area (they''re about $200 each, with a 5% discount from digiboat).
Oh and the extra detail available from the c-map vector charts is extraordinary! It leaves the old electronic Admiralty Charts feeling like, well ... paper!