EDIT: I believe the title and my speculation is either wrong/only partially correct. It doesn't appear to be based on how fast you do it, but rather if the teleportation thing happens or not.
Sometimes when standing up if you immediately start walking around on the boat, you will NOT have the teleport bug happen, if this is the case then, the next time you attempt to sit down it will break your character.
What aspects of the character that breaks also seems to vary, this time I //could// attack and open the inventory, but the hotbar didn't work and I couldn't put anything in my hands.
As you can see I get out of the boat and start walking forwards, I'm glued to the boat a bit due to the inertia bug and this time I don't get teleported backwards, the next time I try and sit down the in-world HUD disappears again and my character has become bugged.
{F5401178}