I just recently purchased a new Lowrance Elite 4 HDI fish finder. I am in the process of installing it on my kayak. This may sound like a silly question but is it ok to turn on the unit on while not in the water? The reason I ask is when I was a kid i thought i remember someone telling me that it was not good to turn a fish finder on if not in the water. Also, if it is ok, does anyone know if it has a demo screen that i can play around with before heading out on the water? Thanks!!