RedactedNarrative: Operator was underway and began smelling something hot. He deactivated his deep cycle battery to alleviate the draw on the alternator to no avail. Approximately one half hour later he smelled smoke and observed flames in his cabin near the ceiling 1/3 from the bow on the starboard side. Operator utilized one fire extinguisher to no avail. He radio'd for help and abandoned the vessel with his child. The vessel burned and sunk. The vessel was purchased the Tuesday prior to the incident and had been in the water for only three days. The fire is believed to be electrical in nature as there were no additional sources of heat or flame in the area.