Ok guys here is something i found this weekend my terrova (us2)is mounted on a MKA-21 Quick Release Bracket made of plastic so when mounted to my aluminum boat it is not grounded to the boat. when I use a ground wire from the frame of the minn kota (us2) to frame of boat i get different readings coming from my us2 when not in the water on my 597ci hd so the question is when mounting minn kota TM with us2 should the trolling motor be grounded to boat or not someone should check with humminbird/minn kota