RedactedNarrative: THE CAUSE OF THE SWAMPING IS UNKNOWN AT THE TIME OF THIS REPORT.  THERE WERE NO LARGE WAVES AT THE SCENE THAT WOULD HAVE SWAMPED THE BOAT FROM COMING OVER THE STERN.  THE BOAT DID NOT APPEAR TO HAVE ANY HOLES OR FIBERGLASS DAMAGE TO THE HULL.  POSSIBLE CAUSES WOULD BE THE PLUG WAS REMOVED AND PUT BACK IN, SINCE IT WAS FOUND TO BE ONLY FINGER TIGHT, OR THAT THE MAIN SEAL AROUND THE LOWER UNIT FAILED.