does a trolling motor need a title or to be registered?

No

Yes and no. It depends upon your state...you need to check with the titling agency in your state. I live in Texas, and our agency is the Parks and Wildlife Department. Most likely you will not actually register the trolling motor, but the boat, as it will now be considered a "Powerboat". I know this may sound silly, but I had to register a flatbottom boat because I wanted to run a trolling motor on it. The State did not care about the trolling motor (what kind or how powerful), but since it now made the boat a "Powerboat", the boat itself had to be registered. Hope this helps!

If it has a motor of any kind, even a trolling motor, it must be registered before use.

http://www.boat-ed.com/sc/handbook/register.htm