No, it is the small wires to the bow. Wire diameter over distance = resistance = voltage drop. The smaller the wire, the more resistance it has.
Typically a fuse panel is wired with 10 guage. Circuits from that are probably 18 guage or smaller.
All the connections involved in a wiring harness = more resistance and future failures.
Humminbird recommends their units powered directly to the battery and extend the power cord with larger conductors with a spade type fuse/holder at the battery. Solder and waterproof wire splices. I use 12 guage marine grade conductors for by bow unit power supply. I first used the boat wiring harness (too lazy to do it right) when I first got the Tracker and it did OK until I installed a Side Imaging unit there. Kept having shut-off issues. I don't any more.
When someone complains of unit operating issues, the first question is how is the unit powered?