I don't have one and losing my heading when on the trolling motor is driving me crazy. I am using Helix 12's G2N at both bow and the console. I made an appt to have the heading sensor installed for the bow unit. They are suggesting I have another installed for the console unit. This stuff baffles me and they could not explain clearly enough why the second one for the console unit would be helpful. For my fishing so far just the bow unit is a problem when the boat is barely moving. I have not had a problem at the console that I know of. Can someone explain the need for the second heading sensor. Thanks.