Kiting and sailing by the lee
Sailing fast in an optimist is hard especially in downwind, the boat doesn’t accelerate enough to enable surfing as other sailing boats might. There are 2 fast angles on a run, one is broad reaching and the second is sailing hard enough by the lee, both require the use of a wind indicator and The sailor (Rosetta) is ensuring it is pointing away from her.
In each of those there are very delicate nuances that makes a significant speed difference.
Here the sailor was practicing finding the correct angle to sailing by the lee to maximize speed, it required her feeling how the speed of the boat changes with the slightest angle changes of the boat.
Being a very talented sailor she caught it up brilliantly and was surfing waves and pumping the sail.
Her upgraded downwind speed helped her to win the Taiwan national games.
A big part of Toplevel Sailing sail coaching philosophy is to encourage talent and to encourage using the feel of the boat as a tool of improvement, as well as allowing our sailors a better understanding of the physics of sailing and how to make the boat go faster