lowrance 27 c

having trouble when im in shallow water under 5 feet it its showing lines across my sonar screen like its messed up???? also when i plane out faster speeds i lose bottom on sonar any help please?

[yarcraft91]

Start by checking the transducer "attack angle". The transducer should be mounted such that the back end of the transducer is very slightly lower than the front when the hull bottom is level front-to-back. A transducer that is parallel with the hull bottom or tilted down in front may perform as you describe. BTDT