We had a club meeting last night and a guy that is well versed in electronics gave us a talk on the use of sonar/gps ..His thought,ALWAYS ON AUTOMATIC SeTTING ON SENSITIVITY,,as for you and your specific problem,i would guess putting them on a source other than the trolling motor and on another battery seperate from all the others..keep tranducers as far away as possible from each other..thats what I heard,,,ss