RedactedNarrative: VESSEL 1 WAS HEADING NORTH ON BISCAYNE BAY WHEN OPERATOR ENCOUNTERED A LOSS OF POWER WHILE ATTEMPTING TO GET ON PLANE.  OPERATOR NOTICED BLACK SMOKE COMING FROM ENGINE COMPARTMENT. OPERATOR CALLED IN MAYDAY TO USCG. PASSENGER PUT OUT FIRE WITH FIRE EXTINGUISHER AND OPERATOR PREPARED DINGY FOR EVACUATION. FIRE WAS QUELLED AND ALL PASSENGERS AWAITED ASSISTANCE FROM USCG, FWC, AND TOW BOOAT US.