Originally Posted by Dougcole
A copy of your cruising permit would be the safest way to go, but if you don't have it I wouldn't sweat it too much.
I would sweat it. Yes you sometimes get by without it. But I know some one who was denied boarding till they got a copy of the cruising permit faxed to the airline.
Some times a letter from the captain with the ships stamp and details in it will work too.
It's up to the each airline and each counter person as to how lenient they want to be with the rules. So I prefer not to risk getting some one who is having a bad day and wants to pass that along to me.