RedactedNarrative: Based on witness statements and evidence at the scene, the operator was attempting to start his vessel after launching it at Poplar Springs boat ramp.  The vessel had started once and subsequently died.  Operator continued to attempt to start the engine at which point the vessel exploded.   The resulting blast propelled Operator approximately 20'' into the air, based on witness statements, and separated the deck from the hull of the vessel.  The vessel then burned to the water line before sinking.  Operator was helped from the water and transported to University of Tennessee ER by EMS for treatment.