A propulsion unit control system is provided for a boat having plural propulsion units provided side by side and electrically connected in association with two adjacent operation levers. In addition, to pilot tones which may be existent within an orthogonal frequency division multiplexing signal, one or more data tones within that same signal may be employed to assist with channel estimation. This invention also relates to uses of the compounds to make medicaments and treatments comprising the administration of the compounds to animals in need of the treatments.