While on a ship in single-player survival mode, I've twice been sent flying into the air by the ship's collision boxes. First time I was trying to figure out if there was a way to climb the tall mast, and was catapulted so high that when I landed I instantly died. The second time I was sailing in the middle of the ocean when the same thing happened, only I was attempting to jump onto the prow of the ship.
Not wanting to lose my fully stocked ship, or character...