I think there is some confusion as to how a GPS works. Your pucks or transducers have nothing to do with the actual marking of a waypoint. They only allow you to see what you want to mark. When you mark something, that location is marked where the antenna is at that time. For instance if you have your transducer on the stern of your 20' boat and a GPS with an internal antenna on the bow, your waypoint is already 20' off. Is this not true Joby or am I leaving something out?