RedactedNarrative: Vessel 1 was noticed by the Marine Deputy on patrol, at the mouth of Municipal Marina in Pere Marquette Lake. The vessel was smoking and the four people on board were using a 5 gallon bucket to pour water near the stern of the vessel. The operator stated that the injured person was the one that put gas in the vessel. But once they had gotten underway they heard the explosion. The people were yelling "Fire". The operator/owner stated they tried using the fire extinguisher but it broke but thought they had put the fire out. The Marine Patrol assisted everyone with putting PDF's on (from Marine vessel due to no PDF's onboard vessel 1), before transferring to Marine vessel. The injured person sustained burns to the skin on his leg and the others on vessel had minor burns but refused medical attention. The Marine Patrol returned to the vessel to clear area and follow vessel that was towed to launch. Beer cans and liquor was visible on board, and a sobriety exercise test performed and was determined to not be a factor in the boat fire.