I bought a Helix 7 SI last year and am still figuring it out. I have navionics card with it, however, I am interested in an SD card for mapping lakes that are not one navionics. However, I've never done it before and am a little confused as I google which card to get. My understanding is that I need a zero line SD card and software if I wanted to transfer it to a computer. I found something like this on Amazon
https://www.amazon.ca/Humminbird-600033-1-AutoChart-Xero-Line/dp/B00S3TU2F8/ref=sr_1_3?dchild=1&keywords=autochart%2Bzero%2Bline&qid=1622227509&sr=8-3&th=1 however, I am still confused. Some comments say it works for autocharting. Other people say it has southern US lakes on it and won't autochart.
Can someone link me to something that will work?