The drive noise was resolved by replacing it with a rubber joint. In order to be able to move forward at very low speeds, I replaced the positive and negative wiring of the motor and reversed the forward and reverse directions. The high frequency sound generated by the amplifier at low speeds was reduced by wrapping the receiver box in a urethane sheet and pasting a 1mm rubber plate under the deck. I increased the rudder angle to be able to make small turns.
  / 1111875430160901