For clarification of the 'rules' on this, I would call your nearest USCG Regional Exam Center and ask them. I'd give you the link but it is being blocked due to not enuf posts. Google USCG Regional Exam Center or STCW...
has addresses and phone numbers for the REC's, application forms, etc.
Please let us know what the REC says since I've seen this Navy question come up before.