RedactedNarrative: Had boat serviced for summer.  Towed from Oregon. Launched at Rockford Bay County Launch. Idled through no wake zone for approximately 10 minutes to a private water toy.  Turned off engine and a few minutes later observed white/grey smoke form engine compartment.  Passengers exited boat with PFDs. Passengers were picked up by a passing vessel that towed boat to a dock.  Boat owner and dock owner, names unknown, each discharged a type B1 fire extinguisher in the engine compartment.  Worley Fire Boat arrived on scene, confirmed fire was out and boat was safe to be towed to the Rockford Bay launch. KCSO Marine Patrol arrived at the launch to collect accident information an conducted a Vessel Safety Inspection.
NameOfBodyOfWater: Lake Coeur d'Alene
NearestCityTown: Coeur d'Alene