Yacht Controller transmits simultaneously on two individual radio frequency bands which are widely spaced in the radio frequency domain. Therefore, if the communication between the transmitter and the receiver is disturbed by a radio-frequency transmission device operating in the immediate vicinity either legally or illegally then communication and control continues by the other band. In the extremely unlikely event of simultaneous interference on both bands, the receiver activates the buzzer for short periods, thus signalling the momentary interruption of communication with the transmitter. Due to the security of the communication protocol, it is not possible for the system to accept incorrect commands.