RedactedNarrative: While the operator was sailing on July 13, 2017 in Lake Salvador he was knocked overboard off the starboard side of his vessel (IN-9899-DU) by the shift of the boom, around 4:30pm.  Operator was the only passenger on board and he was not wearing a PFD.  Operator was found by a passing boater, treading water around 8:00 am on July 14, 2017. The IN-9899-DU has remote steering. The primary contributing factors to the incident are the operator’s inexperience. He stated that he was currently teaching himself how to sail and is new to sailing.  The secondary contributing factor is the weather, when the wind blew causing the boom to shift.  At the time of the interview, alcohol or drugs are not believed to a contributing factor.  Operator is being treated for dehydration and a rash on his legs from being in the water.