I'm looking to start upgrading my 15 year old depth/fish finders. I don't understand everything I should about the new equipment. I'm wanting to start at the bow with something to tie to at the console in the future. I jig fish hand held gps marked brush in the spring and troll at other times. I've been looking at 7 to 9 inch lowrance units. All suggestions including other brand welcome. Also what type transducer.