I use a capps and coleman style rig with a 1/2oz sinker. you want your line to stay vertical, so just tap the trolling motor and go slow enough that the lines stay vertical. If the line stays pointed toward the back of the boat let off the trolling motor until they are vertical and start again, but SLOWER. the slower you can go the better.
+1 above
You can try jigs but sometimes crappie are so lethargic in winter, minnows are the bait of choice.
I have been trying out the WM troll techs and really like them.