FAQs Where can I buy cartridges? Can I see the charts I'll get before buying a cartridge? How can I find out about cartridge updates? My cartridge appears to be faulty, what should I do? I’ve bought a new chartplotter and my old C-Map cartridges don’t fit. Can I exchange them? What’s the difference between Local, Standard and Wide C-Cards? What is the chart datum? Why do I sometimes get a blank screen when I zoom in? How can I store waypoints? How can I view my cartridges at home? How do I operate the Tide Info™ function?