I put it on a 2x4 and attached that to the side of my boat. I tried it out yesterday and it sees the bottom well. It did not show any fish. I made sure that the fish ID was on and tried all different configurations. NO FISH BLIPS! I know that there were fish there, I saw them jumping. I trolled over and around the places that they were jumping and still nothing. Just a nice bottom. How would I check that this feature is working? Catch a fish and stick it under there? That is my only guess.