hummingbird piranha question
I have not used the Humminbird, but as with most LCDs they are a little more difficult to interpret what one is seeing on the display since it is stationary while ice fishing. You'll probably see your jig as a solid line on the display and fish will probably show up as squares made up of only a couple of pixels. There is also a delay in the display, unlike a flasher, which is "real time". Spend some time with it and you'll figure it out.
As for the transducer, contact Humminbird to find out which ( if any iceducers would work with your unit. One could always rig the skimmer transducer to work although it would probably be difficult to rig it to shoot dead vertical-the beauty of floating iceducers.
Last season I had to use a Fishing Buddy portable while my Vexilar was being serviced, and while it worked, it was WAAAY inferior to a flasher.
LCDs are great for open water, but for ice fishing they leave little to be desired. Good luck!!