Originally Posted by Simon B
Cookee, whats a hook?
It usually happens during a turn or if a bit starts bouncing around (as this video shows graphically) resulting in a loss of control - The hull enters the water after getting some air at a slight angle and with a bit of roll, ie leaning to one side slightly, it then works a bit like a snow ski does and it grips the water and follows the curve of the keel resulting in a violent turn.
It can happen in a turn if the boat is bouncing around a bit, in racing this can happen if you're following in someone else's wake or it's a bit rough - all of the above can be cured with a little less enthusiasm with the throttle!
Hope that explains it!