I have the Elite TI2 7 at the bow of my boat for the trolling motor. When I graph around off shore find a waypoint and get to the waypoint on my graph, I’ll put spot lock on and try to keep my boat a certain way. Sometimes it will turn of course because of wind or current, but my graph shows my boat position in reference to my waypoint I set, being very sporadic, acting like my boat is doing turns. I don’t have any kind of precision compass. So what do I need so my boat position will stay still and be a lot more accurate? This makes fishing offshore very tough!