Vessel was heading to Key Largo when the port engine started smoking. Operator turned the engines off. Operator opened   the access hatch to ventilate and examine the engine. The operator decided to turn vessel around and proceed back to Miami Beach Marina on one engine. The operator and occupants heard an explosion.  They then observed a large fire in the rear of the vessel. 
       Operator sent a mayday call. He and the two occupants had to abandon ship due to the large fire.
KEY BISCAYNE                  