In addition to twin rudders which have become a familiar design feature over the past ten years of so, this sports boat also has what appeared to be a steerable trim tab and horizontal control.
The twin rudders are quite short but presumably their location close to the waterline mean that the leeward rudder is effective when heeled.
Presumably the horizontal control reduces pitch and maintains for and aft trim plus contributes slightly to directional stability but I'm guessing it's real purpose is to generate downward force at speed to provide additional sail carrying capability (the keel is high aspect with a lead tear drop).
The Jester Dinghy: The Known and the Unknown
3 hours ago