RedactedNarrative: BOAT OWNER STATED HE WAS GAINING SPEED ON HIS BOAT WHEN HE HEARD THE ENGINE HESITATE. SOON, THERE WAS SMOKE COMING FROM THE INBOARD MOTOR. OPERATOR SHUT DOWN ENGINE AND ATTEMPTED TO EXTINGUISH THE FLAMES WITH ON BOARD FIRE EXTINGUISHER. OWNER SAID HE HAS NO IDEA WHAT CAUSED THE FIRE, BUT PLANS TO TAKE IN FOR SERVICE AND INSPECTION. OWNER/OPERATOR WAS NOT INJURED AT ALL. SAFETY/COMPLIANCE CHECK REVEALED FIRE EXTINGUISHER WAS EXPIRED AND THERE WAS NO THROWABLE PFD ACCESSIBLE. OWNER GIVEN WARNING FOR THOSE VIOLATIONS.