Suggestion, get a nice DI (down imaging) fishfinder. Lowrance HDS or Humminbird DI. It Jury-rig your fishfinder with a 14.8V Lithium Ion battery, and you'll have plenty of fun on the water. Fisher finder with DI, on Craigslist, is about $100. Add the LIon 14.8v pack with the charger, it will be another $60.