Owner stated that he had turned the blower  on, prior to putting the boat in the water. Drove the boat for a short distance and then checked the motor and everything was fine. Owner then drove the boat around the lake some more then stopped to check the motor again and things appeared to be fine.  He  stated that he was heading back to the boat landing to pick up his family traveling approximately three quarter to full throttle when he heard what appeared to be a puff and then there was a little black smoke. He then stopped the boat and opened up the motor compartment and noticed flames coming from the engine. He  grabbed his fire extinguisher to put out the fire and was unsuccessful. He stated the flames got too big and there was a lot of heat so he decided to jump off the boat into the water and swim away from the fire.
Glenwood                      