Been there, done that, nothing helpsI have tried all combinations of wiring and shielding and kits known to man. the digital motors on these TMs play havoc with the Humminbirds. I have 2 on the bow (SI and standard) and both have interferance. The problem is the digital motors actually turn power off and on digitally (really fast) to control the speed, not a variation in voltage (0-36volts). The result is that sometimes, the frequency of the on and off, is close to the sonar frequecy and HB is bad about not filtering this internally. Has nothing at all to do with the actual power wires to the either unit, it is the field around the motor. I have tried everything. I have held the transducer away from the motor and once about an inch away, interferance is gone. Best thing I have found is with the boat out of the water, run the TM from slow to high and watch the graph for interference. Put a Sharpie or tape mark on the TM speed control where the least interference is and then on the water, you can set the speed control in that area. I have a Motor guide and if I thought a TM change would fix it, I would love to use that as an excuse to buy a fourtrex.Hope this helps a little. Milton