RedactedNarrative: After backing out of his boat slip, operator shifted into forward, then suddenly realized that he was not going to clear the pylon at the end of the dock. He turned the boat to port, however the boat glanced off the pylon throwing operator into the front passenger seat where he struck the back of his head.  The vessel then went into a tight spin circling twice before hitting the pylon straight on.  The impact threw operator forward causing a laceration to his face.  The motor shut down on impact.   Operator may have lost consciousness from the incident because he had trouble recalling exactly what happened after that point.