Vessel 1 was travelling north on Lake White (toward the back side of the lake).  The Operator reported that he accelerated and the engine on Vessel 1 started to sputter, so the Operator returned Vessel 1 to idle speed; at this time the back of Vessel 1 exploded into flames.  One of the Occupants aboard Vessel 1 tried unsuccessfully to put out the fire with a fire extinguisher and then a cooler of water.  The two persons on board Vessel 1 then jumped into the water where they were picked up by another boater in the area who witnessed the incident.
Waverly