RedactedNarrative: Subject was operating Vessel 1 (V1), a 15 foot tiller handle vessel in the Intracoastal Waterway (ICW) with two (2) persons onboard, traveling west.  Vessel 2 (V2), the 94.5' tug boat Helen Merrill was traveling east bound, pushing two (2) barges.  For an unknown reason, V1 collided with the front barge being pushed by the Helen Merrill.  After impact, evidence indicates that V1 swamped then capsized.  Operator of V1 appears to have sustained head injuries during the collision/impact.  Passenger of V1 sustained serious internal injuries and a laceration to her leg.  Passenger of V1 was retrieved, holding onto V1, by V2.  Operator of V1s body was recovered in the ICW.    Passenger of V1 was transported to the hospital and has had several surgeries.  There was evidence of alcohol in V1.  Toxicology tests are being performed on the operator of V1 at autopsy.    The  ignition safety switch lanyard of V1 was still attached to the engine.  Both vessels were equipped with adequate PFDs but weren't being used at the time of the incident.  Neither subject in V1 was wearing a PFD.