SI is a must, DI not so much. But remember...ya gotta be moving slowly in a straight forward/reverse direction for either to work as intended. Traditional 2D sonar works all the time, that's what you will use to see your jig under the transducer. I use an old H-bird 999 on the bow in split screen 2D/SI, and an older 997 at helm set on SI, but I still have 20/20 vision I'm told. Larger screen couldn't hurt. Like they said the base mapping isn't great. Protip- don't run SI range out too far, 60 ft or so is plenty for these shallow lakes like Rend. You'll figure it out just take lots of gas, an SD card to record pics, and go slow.