FWIW, I have a Hummingbird Piranha too and I'd recommend them. Runs on 8AA batteries and reasonably compact. My only issue this year was that the suction cup would fall off the hull of the boat. I suspect that this was due to an old suction cup and a kevlar rental boat with plenty of hull scratches. One of my winter projects is going to be making a floating transducer mount, so that it can float alongside the boat instead of sticking to the hull.

Ranger