Help needed to wire new fish finder

[ccm]

Hi,
I had a Lowrance X102C fish finder on the bow of my bay boat that died so I purchased a Lowrance X-4 unit to replace it. The X-4 has two wires, one black and one red. The old unit had 3 wires. One larger wire and two smaller wires. I have been told that the larger wire is for networking purposes (which I never used). When I cut the original connection off to wire in the new unit this is what I found:

Larger wire...it contained 3 small wires colored red, black and white.

1st smaller wire...it contained 3 small wires colored red, black and one
wire that was naked (did not have any covering).

2nd smaller wire...it contained 4 wires colored blue, orange, yellow and
one naked.

I will also mention that the wires contained in the smaller wires are very small wires.

I need advice on which of these original wires that I should connect the red and black wires from my new unit.

I appreciate any advice you can offer.