![Image](https://cdn2.bigcommerce.com/server6000/7efdf/products/8906/images/21643/Fantaic_WS_Flow_Foil_H9_Combo.001__49358.1509576446.500.659.jpg)
I would like to suggest an alternative mechanism
There is in the aviation world a phenonemon know at phugoid (or fugoid) motion. This is a slow pitch oscillation of the aircraft, which if not controlled can and has resulted in significant deviation from the flight path (aka a crash). Now I don't have my aerodynamics textbooks to hand, but Wikipedia suggests it can be controlled by tuning the length (and, I suspect, in the case of a typical sailboard foil, the stiffness) of the tail.
Just a thought
Simon