Looking to add a Garmin 520 to my freshwater river boat. Garmin site says it comes preloaded with a map.
I have another Garmin on my ocean boat and know about the blue tooth chip I had to add to view the marine topography such as rocks, depths, etc.
Question is do I have to add any type of chip to the 520 so it will be useful when we run up to the Koyukuk and back? Main purpose of the GPS is to record areas where it was shallow/problem areas on our runs up or down. Precise mapping is not required. Just want to be able to follow the line back home to avoid problems.