I don't think the Navionics chip works with the Garmins. Also, last time I checked, the add-ons offered by Garmin weren't worth much (the 1300 acre lake I fish was missing an entire island!). You can ask them to send you a sample map (fax) for your favorite lake and make your own judgement on the worth--that's what I did. 'Course, that was 3 years ago, so maybe Garmin's add-on has improved.