I'm pretty sure this was unintended. I do not have the high seas booster pack, I have a normal ship. The ship, and key, are mine and belong to me. My friend waited on the boat, while I used my runebook to recall to a bank. Then she opened a moongate for me to return to my boat. I could not travel through the moongate, and got the message in my journal saying that I had to upgrade to the high seas booster pack to use this option. ??? I did submit this bug in the game via the help option. Not sure if the Dev's ever get the time to look at those, so, I thought I'd post about it here as well.