Here's a good picture of the double echo method that I like to use, structure that is hard shows up on the second echo generally it is superimposed on the second echo but you can see what I'm talking about, but something soft like the fish in the picture won't show on the second graph,notice there is no arch as I really think this fish was right on the edges of the beam, but I will still anchor down on a mark like this and give it a try we pullled a 21# Blue from this spot only minutes from placing baits on this structure, before we left I scanned the area and this fish was gone...............Doc
http://img147.imageshack.us/img147/2088/fishdeid0.jpg