Most people go too fast in the winter. It’s critical to slow down. 0.1 or 0.2 mph if slow trolling. This might mean you have to use the slowest speeds on your trolling motor. Another option is to put out an anchor until it just hits. Use the trolling motor to move both the boat and anchor for several feet. Stop and fish. Repeat.
If casting, retrieve very slowly. A freefall jig can be fished in moderately deep water. Stumps or the outside edges of brush can be pinpointed with repeated cast. Or, use a float so you can slow the bait or let it sit still. You can maintain the right depth. A slip-float lets you fish as deeply as you want. -TH