Uh, I think the reason the transducer has to be hooked up is that the power cord and transducer share the same plug. Kinda hard to run it in demo mode, without any power.I don't think it hurt anything. My Eagle actually has a mode that you can play around in. It gives you a fake underwater picture so you can get used to the functions of the unit. I am not for sure if it is feeding from the transducer in this setting but the transducer has to be hooked up.