My lifting cord for my trolling motor continues to wear after only a few uses, and I have had to replace many times. Is there a better way? I'm thinking of using some sort of SS cable or something. Any ideas would be greatly appreciated.

I have had many trolling motor cables break on me. It is a real pain in the a** when you are trying to get trolling motor out of the water and the cord breaks. I have always replaced with rope but I'm thinking that a plastic coated cable would work really well for this, like the kind that they have for dogs to run around in the yard.

Where does it wear, and what causes the wear?

You could use the plastic coated metal cable, but once the plastic coating wears off, you'll be grinding on the surface that is causing the wear on your cord now.

I'm guessing that it wears where it rubs the gunnel of the boat as you pull the line.  If so, hardware such as this might solve your problem.

http://www.iboats.com/Anchor_Rollers_Mounts/dm/view_id.217392

To make the cord last longer, before installing, treat the cord with  bow string wax to reduce friction. Eliminate any rough areas that may be causing too much friction.

Lifting cords do wear but one that's lasting such a short period of time seems to indicate you've got a problem somewhere.  Carefully check the cable route and make sure you've got no burrs or rough edges somewhere along the line causing the premature failure.  

My Minn Kotas came with a cheap tin groument going thru the bracket. Had it replaced with a much nicer nut with a hole thru it. Came from the Minn kota repair guy.

Garnet

Sounds like the trolling motor manufacturers need to start installing ceramic guides to prevent scuffing of the rope.

I installed SS cable on a prior boat.  It works great with one exception.  It slowly chews through the tin grommet and then starts chewing through the aluminum frame.