  NM10/55 (3/5/55) --  OBSTRUCTION -  COE ADVISES THAT AN OIL DRILLING RIG ON A PONTOON WAS LOST OVERBOARD FROM A BARGE IN ABOUT 14 FEET OF WATER IN APPROX. 28/59/40.00N, 089/11/45.00W (NAD27).  THE OBSTRUCTION IS NOT VISIBLE ABOVE THE WATER AND IS REPOR