In trying to obtain a Cruise Ship job I was asked to obtain the seamans or seafarers Discharge Book. Could you define what this book is and how do I go about trying to obtain one so that I can get this job.

I may well be wrong but my understanding it is a licence or rating. Normally gained though going through training to be a seaman.

You may check out this web site for more information:
http://uscode.house.gov/download/pls/46C73.txt