Just bought a boat with a Garmin 188c. It also came with a plug for in my house, mapsource bluechart cd version 4.01 a usb data programmer and mapsource data card. I've figured out using the unit but my problem is the chart is for an area just north of my boating area. I spent a few hours trying to figure out how to get the chart that i need to display on my computer so i can download it onto the data card but i'm not having any luck. Anyone out there that could offer suggestions? Thanks in advance