Here's what I have,,,,,,14 ft. jon boat with a 15 horse evinrude. Works great. I'd like to get a fish finder for use in our river and some lakes. Do they make them that takes like 9 volt batteries or do I need a 12 car battery? What would be a good finder and depth finder for my boat. Don't really want to spend a pile of $$$$. Give me your ideas please. Never had one before. Don't really want something that's big and bulky.