I found the following on Humminbird's FAQ: (
https://www.humminbird.com/faqDetail.aspx?id=14216 )
Q: If my friend has a ZeroLine card can I copy Autochart Live data from my ZeroLine card to his ZeroLine card?
A:
Yes. Autochart Live data can be copied or merged. Autochart Live files are stored on the ZeroLine card in the "acdata" folder. These files can be copied to and from ZeroLine cards. Data copied to a single card from two different cards will be merged together by Autochart Live automatically.
I tried this out. I have done some mapping on my ZL card and my friend has done some mapping on his ZL card. Some of that mapping is on the same lake, and some of those maps are on the same spots on the same lake, while others of course are not. I pasted his acdata files into my acdata folder on my card and I got the message that 10 of his 63 files contained the same name as files in my acdata folder. I opted to skip those files of his with the same name rather than replace mine. When I fired up the unit, his and my maps appear to have merged successfully.
Is there any work around to some of the files sharing the same name? We plan to continue to share our our charts and I imagine that this issue will only become more prevalent and prevent us from sharing certain data. Humminbird customer service rep had never heard of this issue and had no advice.