According to Peter C's excellent kite surfing handbook ...
kitesurfing-handbook.peterskiteboarding.com/progression/kite-trimming"...trimming the kite so it flies in an optimal manner and you are not overpowered or oversheeted."
This is an
essential technique to master and I don't think trainers teach it enough or correctly.
It all comes down to the AOA (Angle Of Attack).
Kites are no different than an airplane wing. They have the same shape structure looking at a kite from the side (see above link for diagrams).
Essentially ...
When you DEPOWER your kite you are effectively PULLING IN the
LEADING EDGE (or front of the kite facing the wind) of the kite down, which creates less AOA.
When you POWER your kite you are effectively RELEASING OUT the
LEADING EDGE (or front of the kite facing the wind) of the kite UP, which creates more AOA. Again look at the green arrow on the diagrams.
A lot of people think that you are trimming the REAR of the kite. No, that would be the opposite effect (pulling in the line will POWER the kite as opposed to DEPOWER it, and of course releasing the rear lines will DEPOWER the kite). But thank fully I don't think any modern kite does this.
So why is it easier to re-launch when the kite is fully DEPOWERED? Because of the position of the kite relative to the wind. When the kite is not at the edge of the window, the kite is already what I called "highly aspected". In other words, it's catching wind like as if it's fully powered up.
If you release the centre lines to create more AOA (powering the kite), you are actually NOT creating power and why it's harder to re-launch. The angle of the kite is facing more away from the wind, hence catching less wind.
But essentially a kite like the shape of an airplane wing, is naturally designed to "move forward". It's shape allows it to be pulled "into the wind" (the upwind effect), and so the more it can do this, the easier it is to re-launch.
Cheers
