RedactedNarrative: On or about May 26, 2018 at approx. 15:30, V1, a 2011 17''6" Bayliner with TN registration of TN 7685 EE and HIN of BLBA07CUF112, was traveling downstream in the area of Hwy 411 bridge on Tellico Lake.  Operator/Owner was towing his brother on a tube when Operator lost his hat.  Operator made a turn to retrieve his hat from the water.  Based on the statement of Operator, he left the operators chair with the vessel in gear and under power but traveling less than 10 mph and proceeded to the bow of vessel.  Operator asks passenger to slow the vessel down a little more.  Based on statements from the operator, and passengers, either subject pulled the vessel throttle too much causing Operator to be ejected from the bow port side or Operator was leaning/stretching too far over the boat to retrieve his hat and fell overboard and was struck by the vessel prop as it passed over top of him before subject could get the boat into neutral position.