When a fish finder isn’t returning good data for whatever reason, try “peaking” the transducer. It’s a way to fine-tune the settings so the transducer will return a clearer picture even in difficult conditions. Do this in four steps: First, change the range to three times the actual water depth; second, increase the sensitivity until you see a second “bottom” underneath the first one on the main screen; and third, slowly reduce sensitivity until you have a pretty good read on the first “bottom” result. Finally, put the range back to its normal setting.