I bought a Humminbird 161 to use on my prowler 13. It's an entry level combo fishfinder/gps unit. I got the idea from Jim Spears site here. Jim uses a hull mounted transducer held on by bungee cords and nestled in a foam block. I want something more hydrodynamic and have considered mounting it inside the hull. I was wondering if anyone else has done this and what the results were and any mounting ideas/how you've routed the cables, etc.