RedactedNarrative: The owner/operator prepared to launch his 1991, 42 foot Fountain Lightning motorboat (MN2906LM) at the public boat launch at Lakefront Park in Hudson, WI located off of 1st Street.  Operator was in the boat as his brother, backed him into the water.  Once in the water, Operator started engine one.  Operator then started engine 2, but as he did so, engine 1 killed.  Operator went to restart engine 1 and a large explosion occurred sending boat parts into the air.  
  
  Operator and witness attempted to extinguish the flames.  At one point the vessel's halon fire extinguishing system deployed and extinguished the flames, but the flames returned a short time later.  The operator backed up his truck and hit the brakes, sending the burning boat floating out away from the launch.  The flames were eventually extinguished and the boat was brought back to shore, heavily damaged.  No injuries were reported.
  