Assuming both units would support the same transducer, (power and frequency) you would need a way to switch the cable from one unit to the other, I.e. selector switch.I've got a hummingbird helix 5 on our boat . It's mounted on the port side. What I would like to know is if I got another smaller hummingbird sonar can I run both units off the same transducer? Thanks for any help