RedactedNarrative: The Operator with one passenger were recreating on Lake DuBay and were returning to their boat landing.  Operator was travelling west under the State Highway 34 Bridge and the Canadian National Bridge.  The Operator was seated in the driver seat at the controls and was sitting on a seat bolster which allowed him to sit higher in the seat. The Operator was operating at planning speed and travelled under a span of the railroad bridge that was 9 inches lower than an adjacent span which most boat traffic utilitize.  The top of the Operator’s head struck the first girder of the railroad bridge resulting in severe head trauma.  The Operator fell backwards and landed on the bottom of the boat and was unconscious, but breathing.  The vessel travelled a few hundred yards west where it came to a stop in open water.  The Passenger called for help and two adults from a residence near by responded by pontoon boat.  One of the responders operated the boat back to their private dock where emergency personnel transported the Operator to a hospital.  The Operator subsequently passed away as the result of his head injury.