from Hung Vu's kitesurfing school website
To jump, you need to be in a powered up situation where you can lock
the kite in at 45 degrees vertically or making a small sine wave
between 35 to 55 degrees vertically. If you have to make a larger
sine wave, you simply don't have enough power to jump.
While moving on a beam reach very fast with the kite locked in at 45 -
55 degrees vertically, turn the kite upward/backward to 70 - 85
degrees vertically in the backward direction (the stronger the wind,
the higher you can send the kite). Once you have checked that the
kite is moving toward the right direction, continue to look forward
and move the board in the same direction (don't look at the kite as
that will make you go down wind and loosen up all the line tension
necessary for jumping). You must have the feeling of "I am going
crazy" as you have sent the kite through the power zone while moving
fast forward and not looking at the kite.
Once you feel the line tension is strong enough (the same feeling
when you are overpowered), flatten your board and extend your legs
(simulating a very light jumping action) to jump. This will be your
last contact with the water so it is also the time to create any
needed momentum to do the trick you want (table top, backward/forward
loop/spin, etc.). When to release the edge and jump is dependent on
how fast you are moving forward and the kite is moving backward. In
the beginning it helps to start counting (one, two three, etc.) after
you have sent the kite backward/upward. You will find the right time
to release the edge after a couple of trials. If you release the
edge too soon, you will slide down wind instead of jumping. If you
release the edge too late the kite will probably yank you right out
of your board.
Immediately after being air born, move the kite forward to zenith (or
slightly forward) to create the "pendulum" effect to sustain your air
time and prepare for landing.
Do whatever trick you like to do (table top, spin/loop, etc.).
Try to move the board in front of you for landing (in high jumps,
don't try to land directly on top of your board, especially in 20-30'
jumps; you will break your ankles that way). Flex your legs upon
landing to absorb any shock.
Move the kite forward/downward to get going.
When you first learn flat water jumping, remember to keep your inputs
small such that you don't over turn the kite which could lead to some
drastic situations (too backward a jump or too fast a landing)