Dear Ms. Havens,
Thanks for posting your request to History Hub!
We suggest that you request your great-grandfather’s merchant marine personnel service jacket by writing to the USCG-National Maritime Center (NMC-421), ATTN: Correspondence Section, 100 Forbes Drive, Martinsburg, WV 25404. Please include his name, date of birth, copy of death certificate, Social Security number, address, and Z or Service number. Their website is https://www.uscg.mil/nmc/.
We hope this is helpful. Best of luck with your family research!