Originally Posted by
Team Colibri
In order to have correct heading while stationary (or drifting) you need a heading-device. Typically a Point-1 but there are numerous options available from many brands, and a NMEA2000-network.
A map can never be better than the data used to create it, but yes you can update your C-Map card through their website. I would preview the current mapping on their website first though, to ensure you get what you want. If you do not, choose another option for mapping (like Navionics) or create your own maps through C-Map genesis or by using Reefmaster.