My grandfather was a tug boat captain. I understand that during WW II, anyone who worked on the water was required to obtain a Coast Guard/Merchant Marine pass. Following up on this tip, and after contacting several archives (including the Coast Guard historian), I was directed to the National Maritime Center, who holds personnel records. They informed me they can't perform a search for my grandfather unless I provide a 'z number' or 'book number'. What is a 'z' or 'book number'? Is this equivalent to a service number? How do I find out what my grandfather's number was? The only information I currently have is his employer during WWII and of course, all personal information (age, address, dob, ss#, etc). I would be grateful for any advice or assistance on this matter. I feel as though I'm chasing my tail! Take care, Tracy