Fishfinder 340C Owner’s Manual 3GETTING STARTED > U NDERSTANDING THE FISHFINDER AND SONARUsing Dual BeamDual beam works best for shallow water (for example, inland)applications. A dual beam transducer can transmit a narrow or awide beam. The water area covered by the transmitted sound wavesis determined by the beam width of the transducer and the waterdepth. The narrow beam provides crisp detail of what is under yourboat, and is very helpful if you are fishing in deeper water wherethe beam covers more area (for example, at a 30-foot depth, thenarrow beam covers the area of about a 7-foot circle).WideBeamNarrowBeamThe wide beam is more helpful in shallow water, because it givesyou a much wider view of objects in the water, including areasbeyond the sides of your boat. At a 30-foot depth, the wide beamcovers the area of approximately a 20-foot circle.Understanding the Fishfinder ScreenExperimentation and experience are the keys to successfullyinterpreting your Fishfinder screen. We recommend that you takeyour Fishfinder out on familiar water, and spend time learning tointerpret what you see on the Fishfinder 340C screen.Think of the Fishfinder screen as if you took a picture from theside of an aquarium in your home. You can see how deep a fish isin the water (how close it is to the top or bottom), but you cannottell where the fish is located horizontally in the water (whether it isnear the front or the back of the aquarium). Remember this whenyou are trying to locate exactly where something is in the water.