In the Winter, Crappie are located in the warmest water in the lake...if warm Springs aren't available, they are in the deepest water. Normally in a frozen Lake the water at depths can still be 38 degrees. Crappie start losing swimming ability in water under 38, so they will suspend. To stay alive they have keen eyesight which allows the to live off of zooplankton which requires little effort to hunt.
If you can find Springs, warm water discharges, old creek beds, sunny rip rap, or something else that may be a couple degrees warmer than the rest of the water, your chances from the bank will improve.