Rickie and others my do this better than me but I'm going to try. On 2d to get arches its relative to how fast the fish is swimming throug the cone or how fast you are crossing over the fish. As you pass over a fish it first shows op and signal increases as you get closer to fish then tapers off as you pass by thus creating the arc you see. If your sitting still or going real slow it's pretty rare to see anything but that blob. The lighter color is going to be to outside edge of cone and darker is going to be more in center of cone. Remember, 2d is nothing more than a cartoon image of what's under you. Plus I'm not convinced the installed transducer on trolling motor are best quality to match your unit. Anything made for universal applications is not great for compatibility.
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Charlie Weaver USN/ENC 1965-1979