But one thing is interesting, are the "banana boards" are hydrofoils or not?
It is quite difficult to get rid of hydrofoils in a sail craft, they are needed to keep forces in balance. Any underwater device capable of generating dynamic lift is a hydrofoil. Even the hull generates dynamic lift.
Common daggerboards (straight, vertical and with symetrical section) generate a vertical lift component when the boat heels: upwards if the hull has a bow up attitude, downwards with a bow down attitude.
Rudders also generate a vertical lift component when the boat heels: downwards with weather helm; upwards with lee helm.
What can possibly be banned in a class are "appendages that generate a dynamic lift force component along the axis perpendicular to the plane defined by the waterlines of the two hulls".
