When I changed over to OT from MS in 1975. It was considered sea duty (kef). When I graduated from OT "A" school in Nov 1975 (Phil Blauvelt instructor), I received orders to Antigua and not Grand Turk island (Bill Winholz got that set of orders). It was because I came from Kef and Bill came from shore duty in California. We were the only two 2nd class petty officers graduating from that class. I lucked out thanks to Kef. As it turned out though, Bill passed through Antigua a few times on the "range liner" and told me that he had a sail boat and he and his wife lived onboard in the Grand Turk harbor. So he liked it there. Good for both of us!
For enlisted (87-07) it was considered sea duty for rotational purposes and was classed as arduous or other. Luckily the Navy gave me the opportunity to "volunteer" for OEF, so I am now a VFW life member.