That is very similar to the unit I have. I run an eagle 640c. I think many of the features and details are the same. I have downriggers on my boat. I have 6,8,10 and 12 pounds cannon balls. I can run them under the boat and go to my sonar features and dial the sensativity in so I see a solid line or fade it out and see a broken, dotted line. When I am in less than 50 fow water, it works better on the 200 mhz setting and 50 mhz in deep water. I like using my cannon balls as a reference as I know the exact depth and size of the ball. Things that make a difference are current, motor noise and interference and water clarity,waves or debris. I hope this helps. If you don't have downriggers, you might improvise.