The tantrum requires a different edging than almost every other wakeboard move. Start from far outside the wake and cut hard with a little more weight on your front foot, loading the line immediately. About halfway to the wake, begin letting off your edge, standing with your head and chest tall and turning toward the shore that you just came from. Be sure that when you hit the wake, your board and body are parallel to the wake and you are looking back toward where you just came from. Lean your head and chest back slightly as you come off the top, letting the wake kick you up and over. You don’t need to “throw” a tantrum; the wake does all the work. Keep your eyes open the entire time so that you can see where you’re about to land.
If you’re coming up short, it means you’re trying to initiate the edge change at the last second and thus throwing the move too early. Feel for the wake with your back foot and let it pop you in the air.