I do find that it is a great tool for getting very accurate bottom readings because you can record your sonar on two logs, upload them to your laptop, and then in a day or two, you go back and Navionics will have updated the map for the area that you fished so you can update your card with that new very accurate information. In trying to set up and use the card I found that there is some information out there but not enough to really use it effectively so I thought I'd post here in case any guys are using the card and having the same troubles I encountered. I have an 899 HD Di SI Humminbird Fishfinder and recently got the Navionics Plus chart card.
