RedactedNarrative: V1 was at anchor, operator attempted to start engines.  After starting Port engine an explosion occurred in engine compartment.
  Vessel caught fire and occupants abandoned ship.
  
  V1 was at anchor just East of Picnic Island in San Carlos Bay.  (Lee County Florida)
  V1 operator attempted to start engines.
  Ran blower for 1 minute prior to start up.
  Started starboard motor.
  Attempted to start port motor, when an explosion occurred.
  On board automatic fire suppression system activated.
  Operator opened rear compartment to assess damage.  Fire started up again, Operator attempted to extinguish with hand held fire extinguisher but flames became too large.  3 occupants put on pfd's and exited vessel.
  
  
  No injuries.