On 8/11/13 at about 1335hrs i was on duty and was at the saguaro lake aid station. I heard a loud noise like someone had slammed a door. A few seconds later deputy said there was a boat on fire near ramp 1. I looked out and saw a boat on a trailer attached to a truck down by boat ramp 1. I saw the engine cover was up and black smoke and flames were coming out of the engine compartment. I drove to the ramp. The boat had been removed from the trailer and was floating near the dock. The fire had moved to the front of the boat. The flames were high and the boat was bellowing thick black smoke. 

I started the investigation. I discovered 5 people had been on board the boat. The boat was still on the trailer and attached. Seconds after the boat was started an explosion occurred from the engine compartment on the rear of the boat. 4 of the 5 occupants were ejected out of the boat into the shallow water of the boat ramp. The operator stated to me he ran the blower for 4 minutes. He started the boat and it ran for about 20 seconds and then blew up. All 4 of the other occupants were ejected from the boat, the operator was not. 

He unhooked the boat from the trailer and pushed it out into the water. He had a small cut to his right shin. I contacted another occupant who was sitting behind the operator chair. He said he had tried to start the boat earlier but it would not start. He said it sounded like the battery was dead. They pulled the boat up the ramp as if leaving the lake. He said they parked and were going to try and figure out what to do with the boat. They contacted a man that was working on his boat and offered to help them. 

That man was interviewed and he said the battery switch was bad so he bypassed the switch. He stated they started the boat briefly on the exit road and it did start. The pulled it back down the ramp. The new operator started the boat and within a few seconds the boat blew up. Rural metro fire and tonto national forest fire put out the boat fire. The boat was still floating but the top was completely burned. We placed the back on the trailer and took it to the storage area,
MESA