I asked on another list about Merchant Marines and this is the response I received. <My father was a merchant marine and the Z number a certificate number of his seaman's certificate of identification issued when he graduated from the maritime school at Hoffman Island, NY in 1943. It is issued by the Coast Guard. I don't know if you have any of the certificates still, but the number is then written on other documents, such as the listing of ships my father was on that he retained from the Coast Guard. My father belonged to the Teamsters Union and the Maritime Union (NMU). He also had a "Seaman Passport" issued by the Department of State. I don't know if any of that will help.> Rose