Tony, Thats how I wired my Navman.
I bought the 3100 wind, repeater and depth. I interfaced my Garmin GPS to the repeater. The 3 instruments are mounted in my companionway cover pod. The gps is out at the helm. I ran all wires to the to the pod. Then I ran one data cable back to the GPS. Power to the pod and out to the GPS are on one source, one fused toggle switch. You can do the same, with all cables to the helm then one data cable from the helm out to the repeater.Ted