RedactedNarrative: A boat fire occurred on May 30, 2014 in Narragansett Bay. The vessel, Equus, was an auxiliary sail (47’) with 4 people aboard headed south toward the Newport Bridge and Castle Hill. At approximately 3.5 miles SW of Sakonnet Pt. Captain noticed an acetone smell coming from the alternator area. Capt placed a call to co-worker who advised that the smell was most likely a malfunctioning voltage regulator. The boat continued to motor sail at 1800 rpm, boat speed 6 knots. A crew member went below and noticed a small amount of smoke coming from the engine compartment. Capt opened the hatch and saw that the smoke was originating from the battery. Capt then placed a radio distress call to the Coast Guard. The smoke was intensifying and eventually turned to combustion and a then small fire. The CG then put out a PAN PAN and notice to all mariners. Fire extinguishers were used but did not extinguish the fire. The fire was now billowing out of the hatches. The CG advised to close the hatch in an attempt to smother the fire. The first vessel on scene was the Pinga Fogo and was approaching the Equus ready for rescue. All crew members including Capt abandoned ship and safely boarded the Pinga Fogo. The Equus became completely engulfed in flames and then sank below the surface.