RedactedNarrative: I spoke to the owner/operator of the vessel which caught fire. Operator advised me that his family arrived at Currie Park boat ramp around 3:00 pm. They loaded up their vessel and backed the vessel in to the water. The vessel was moored at the dock when Operator began trying to start it. Operator was having engine trouble and could not get the vessel started. Operator was able to get the vessel started and began to leave the dock when the vessel stalled out. Operator attempted to get the boat to start again. When the boat started for a second time an explosion occurred under the deck on the starboard side of the vessel. Following the explosion, the vessel began to catch fire. 
  
  According to Operator, when the vessel exploded, his wife passenger 1 (P1) was sitting on the starboard gunnel of the vessel and was thrown into the vessel toward the port side. His son, Passenger 3 (P3) was sitting on the port side of the vessel during the explosion and received a 2 inch laceration on his leg from a piece of shrapnel. The last Passenger 2 (P2) was sitting on the port side passenger seat and was uninjured during the explosion. 
  
  Operator tried to extinguish the fire using a fire extinguisher he had on board, but the fire extinguisher failed to work. I later inspected the fire extinguisher on scene. The fire extinguisher appeared to be full and up to date but was inoperable. 
  
  Investigators conducted an investigation on the vessel to determine the cause of the explosion/fire. The investigators determined that a spark ignited fumes under the deck causing the initial explosion, in turn catching the fuel tank on fire. Due to operator inexperience and lack of proper ventilation the explosion/fire was deemed accidental.