I have a 598 ci si HD unit(cheapest unit that has side imaging) with a transom mounted transducer. I'm finally able to buy a transducer for my trolling motor but will have to use the same unit for both transducers. My boat is only 16' so the way my unit is mounted I can turn it around and see it from my trolling motor location. I know you can use a transducer switch to control what image (transom or trolling motor) goes to your unit but the switch is $85 and they advertise a y cable for $24 you can use instead of a switch. How is this possible? I would think both images would still go to the unit. Can anyone help out this confused individual?