nbsp; Secrets of the sea03/10/02By ROY HOFFMAN Writer in Residence CHARLESTON, S.C. -- Shea McLean was born down in Alabama, in Mobile, on Feb. 17, 1964 -- one century to the day after eight Confederate sailors disappeared in Charleston Harbor on the submarine H.L. Hunley. McLean, a marine archaeologist, finds that coincidence slightly eerie. quot;Some re-enactors pointed out the dates to me,quot; says McLean, 38, a tall, dark-haired man who looks, ironically, a little like Armande Assante, who played Mobile riverboat engineer George E. Dixon, the Hunley captain, in a television movie about the submarine. quot;They say I was...