Good morning Jeff,
I agree with Gary on the shielded wire and I believe that you've picked the right stuff!
To your question regarding kicker grounding, if you have an electric start kicker and its operating correctly, then by definition its grounded. The reference to zinc servicing is interesting but should not be considered part of the electronic interference equation.
You may find it helpful to do a few "driveway drills" to isolate the source of the visual "static" that you are experiencing.
With the boat on the trailer, turn on your Lowrance with NOTHING else on. There should be no interference at this point. Now, start turning on bilge pumps, auto pilots, radios and other potential sources one at a time. If you can get the static to show up, perfect! You can re-route wires and /or replace the offending item.
If not, then it's time to launch and fire up the main and in turn, the kicker. Once you have the source of interference located, then you can formulate a plan of attack whether it be installing "ES" or electronic suppression spark plugs or a NewMar noise filter like this one:
http://www.ebay.com/itm/NewMar-80A-NOISE-FILTER-6-48-VOLT-DC-NEWMAR-ALTERNATOR-SUPPRESSOR-RV-MARINE-/262134038949?hash=item3d086801a5:g:MJwAAOSwo0JWGntz&vxp=mtrFinally, here is an article that may help. Good luck!
http://www.boatingmag.com/how-to/seven-tips-reducing-marine-electronics-interference