I liked the part about the 2d sonar where it mentioned the colors of the arches and where the fish is in relation to the cone angle. I.E., blue being on the outward edge and a red arch being right underneath. I learned a lot from the article. Doc Sampson, a.k.a., Dr. Sonar is so good at explaining things that have to do with the Lowrance systems. I've youtubed a lot of his stuff and the man knows what he is doing.