RedactedNarrative: Operator had purchased vessel during the winter and had reconditioned the vessel. He took the engine hoses and belts and replaced with new ones and other equipment. The day of the fire he had stopped at a gas station and placed 54 gallons of fuel back into the vessel. At the boat ramp he placed the blower on for 15 minutes and then backed the vessel into the water. He started the engine moved the vessel and then shut the engine off to move his trailer and vehicle into a parking space. Upon departing from the boat ramp the boat engine stopped, he place the throttle into neutral and then gave the throttle some pushing forwards (choking the fuel) and the engine started. He proceeded on his journey but shortly looked back and saw a flame coming out of the engine room. He opened up the forward cabin door to retrieve the fire extinguisher when a back draft blew flames toward him. He pushed his vessel away from the dock to protect other vessels. It drifted back and he pushed it out again but this time it came to rest along vessel #2. The vessel's canvas caught on fire. He jumped on this unoccupied vessel and pushed his vessel away and grabbed the canvas of vessel #2 and threw it into the water. Vessel #1 then drifted downstream and came to rest in shallow water when the fire department arrived to put out the fire. Officer believes that when operator pumped the throttle several times it may have caused the float in the carburettor to become stuck which may have caused the fuel to overflow into a hot engine causing fire and one of the fuel hoses the operator replaced was not connected properly.