Im sure you guys probably here this alot. I have an old fishfinder set up on my boat. One hooks up in front of my windshield and the other up by the trolling motor. I am wanting to upgrade. What im wanting is something good for the Mississippi river. I dont need GPS. I would like one with temperature reading. I need it to be able to disconnect so i can lock it up after im done fishing. Im willing to spend up 2 or 3 hundred bucks. What would you guys recommend? What all will i have to do to replace the old with the new? The old one is a Eagle.