Whenever I'm floating as a ghost near boats it might happen that my character becomes stuck. I loose the ability to control my character, he just keeps floating to the direction where I went before the bug occured until I relog or if somebody revives me. This is most likely because my character tries to jump on a boat as ghost, but ghosts appear to lack the action for jumping and so jumping does nothing for them, except that their controls gets disabled.
Become a ghost, enable your lag compensation for higher success and try to fly over or around a boat. Using the mouse might also help to reproduce it.