RedactedNarrative: Vessel occupant statements indicate they were sailing upstream in the main channel in the Concord area of Fort Loudon Lake.  The winds were around 15mph with gusts greater than 15.  The operator stated when he steered the vessel to change directions the boom swung and struck the victim who immediately lost consciousness and was sliding overboard.  He was bleeding from his right ear.  Occupant grabbed him and pulled him into the boat.  The occupants called 911, lowered the sails and returned to Concord Sailboat Club using the boat motor.  He was transported to UT Hospital by ambulance.