Garrymny, as others has said, the downspeed and temp unit give information. Experience tells you what to do with it. You still have to use your eyeballs esp. in the spring! This morning out of Olcott before the winds picked up you might have noticed a slick line in the water at about 50'. That slick line is a "current tell". Usually there is debris in those slicks. Fish will collect along those current lines just like the debris found there. If you paid attention to the weather the day before, you would have seen there was an East wind which blows in cold water and pushes fish to the West towards the warm Niagara flow. As the wind picked up, you might have noticed that there was brown water coming in at 75-100' but the green water was persistent inside that line. Did you see many seagulls today floating around? Why not? If you were trolling towards Wilson and paying attention to your fishhawk, you were trolling into the Niagara current and against a stiff westerly. Your gps speed would tell you that you were barely moving, yet heading into the current as displayed by your fishhawk should have told you that despite not covering much ground, the current against your lure was keeping your lures working correctly. As you gain experience you will learn to trust your downspeed unit and find the units true worth, especially as the season progresses and you begin to fish deeper in the water column to find the thermocline.