RedactedNarrative: The operator was operating the watercraft on flathead river.  He had been pulling the owner of the boat on his wake board.  After they were done, the owner got back into the boat and was sitting on the swim deck, at the rear of the boat.  Passenger #1 was sitting in the front passenger seat.  Operator failed to turn off the engine and thought he put the boat in nuetral, but it was in reverse.  Owner jumped off the rear of the boat to go for a swim.  The boat slowly backed up, hitting him with the propeller.  Owner was stuck under the boat until Passenger #1 noticed what was happening and turned the boat off and put it in neutral.  Owner swam to the surface and was pulled from the water and taken by ambulance to Kalispell Regional Hospital.  The Owner had lacerations to his left arm, arm pit, ribs, and chest.