US Patent 7715574 Audio apparatus for vessel

An apparatus (12) which overcomes the foregoing inconveniences of manually adjusting the audio device (10) volume related to a vessels speed and participants distance behind the vessel in a towable activity. This apparatus (12) controls audio volume levels (14) set at V2 and (16) set at V1 where V2 is greater than V1 and audio volume level (14) is achieved when vessels engine or propulsion shaft RPM is above set point (22) for a time greater than designated by (24), thereby controlling audio volume as a relation to vessel speed.