RedactedNarrative: Engine was not running correctly.  Engine would rev up to a high RPM then kill.  This occurred not less than five times.  Each time this occurred, the boat took on water over the stern until it sunk to the bottom of the lake.  
  
  Both occupants were located in the rear of the vessel, this positioning played a role in the swamping of the vessel.  PFD's and kill lanyard were not used.  Once the vessel was submerged, the operator drowned and the passenger swam (unharmed) to safety. 
  
  Chemical testing of the operator's blood yielded multiple types of drugs, drug use would be a likely contributing factor in this incident.