Not the Gulf, but off Lagos in the late 70's.
I was on a tanker anchored awaiting a discharge berth, we had been there a few weeks. The next ship to us was I think a Scandinavian flag cargo ship.
In the early hours of one morning, she upped anchor and sailed off, to return only an hour or so later, which was a little odd, as when you needed to make water you sailed out for a day or so.
The 3O got on the radio to ask if everything was ok and got the answer:
We were boarded by pirates, now we have no pirates!
Ian