RedactedNarrative: Operator returned to Blackwater Marina after purchasing VA 8256 YY from the previous owner. Operator instructed the marina to fill up the boat with fuel prior to his return. Operator boarded the boat, opened the engine compartment and was instructed by marina staff to turn the battery switch to the #2 position. Operator turned on the ignition and the boat started immediately. After the boat started, Operator saw an explosion in the forward portion of the cabin which then came out of the cabin toward him. Operator jumped overboard to escape the flames and then climbed onto the dock.  Operator received burns to his face and hands.