RedactedNarrative: Vessel 1 had departed from the boat dock when the engine stalled.  The operator attempted to start the vessel multiple times.  Due to fuel/air mixture accumulating in the engine compartment there was an explosion when the operator attempted to start the vessel.  Two of the occuppants sitting beside the engine compartment were burned and one of the occupants who was sitting against the engine cowling received an impact injury when the engine cowling hit her after the engine compartment exploded.