RedactedNarrative: Operator of vessel 1 states he was leaving the Charles Point Marina transient dock, with his engines operating when he heard a loud explosion coming from below. He was operating from the fly bridge. He further stated that he looked to the stern of the boat and observed that the cabin doors were blown open. Operator went below and subsequently observed heavy smoke and flames coming through the floor above the engines. He stated he used his on board wash down system to extinguish the fire. Operator did not recall venting prior to departure.