I have a Piranhamax 220, since discontinued. It has the dual beam sonar technology and it does mark fish below and around the boat. Yes, I use the fish symbols. Gray scale screen. For about $100, its hard to beat the PMax units. It is a base unit and performs the same functions as the more expensive units. For your purposes, it should work great. I use mine on lakes of all sizes, 300 acres to thousands of acres. Won a few local Crappie tournaments with it as well. Humminbird also sells a PMax unit that attaches to the side of the boat and is removeable. I believe it is called the Fishin Buddy. The main feature you want is Dual beam sonar. The sonar will read a circle the same as the depth of the water. If your in 10' of water, it will display a 10' circle. 30' = 30'. Single beam will give you considerable less information and will need to be on top of the fish to see them. Humminbird has a section that explains the beam technology. Worth the read.