[masraum]

Originally Posted by Bill Douglas

Try formatting it with FAT16 using the computer It's the older one. I think the newer one is FAT32 and one of the devices may not like it

Something like this. Modern PCs have several different formats that they can use. I would be surprised if anything still used FAT16, but it's possible.

I think Windows often wants to use NTFS (by default?), but I think NTFS is Windows proprietary, so lots of other stuff doesn't recognize it. FAT32 is usually pretty universal.

What you probably need to do is read the manual for the fish finder and figure out what format it requires, and then ready what formats the GoPro is compatible with. Hopefully, there's some overlap.

Or, have SD cards for each and don't share.