How do you hide your ship when your on an island you know you'll be at for an extended amount of time? Simple answer, chainshot
When on a sloop angle the sails back to it's original position (how it is when the ship spawns) and you will be able to take your own masts down.
I'm sure this could work for the brig and galleon (haven't tested) but you might have to rely on a island cannon to get the galleon's back sail down.
Of course there are ways to position yourself so that players will have a harder time finding you but using this method players will only find you with a keen eye or a touch of luck.
