On june 15, 2013, the owner/operator,and his wife and their 2 children launched their vessel at linville access area.  They drifted away from the ramp and turned the ventilation system on and started the engine.  The vessel exploded causing the fire and totally destroying the vessel.  The ventilation system only ran for about 30 seconds before starting the engine.  The owner/operator grabbed his children and jumped off the vessel along with his wife and swam to shore.  The children were wearing pfds.  One child had on a swim vest the others a type iii.
The explosion was caused by the vapors not being totally vented out of the engine compartment.  However, the spark or flame could not be determined due to the total loss by fire.  Based on experience and research, i feel there was the possibility of a loose wire inside the compartment that could have caused a spark.  It could not be determined if the engine had a back fire flame arrestor or not due to total loss by fire.  The owner had a fuel pump put on the engine two days prior.  I do not feel this was a cause of the ignition.
Note:  the owner bought the vessel two days before the accident from someone who had bought it one week earlier from someone who died.  The new owner had not sent in the paperwork to title the vessel in his and his wife's name.  All paperwork involving the sale of the vessel was destroyed in the fire.
MORGANTON