I have a Humminbird PirhanaMAX20 mounted on my kayak about $100. I am still learning to use it and understand all the feedback. I can turn on the little fishies or leave them off. It is a dual beam sonar but only when you have the fishies turned on. I use it mostly for finding breaklines. It seems to have a lot of manual control...I am still learning to use the zoom and sensitivity to enhance the detail...It was pretty easy this summer finding the thermocline and seeing how it moved through out the season.