Centerboards that change their angle with respect to the hull centerline are called gybing centerboards. I think 505s have them and some older I-14s had them (do they still?). The action is automatic - the back edge of the board is fixed while the front is allowed to move slightly(clunk!).

The important question is: does using a gybing centerboard improve the lift to drag ratio of the hull and appendages as a system? (not always)


Inward canted boards:

Inward canted boards can begin to work at speeds where the lift to drag ratio of displacement hulls starts to worsen. They work better when the side load on the board is a high fraction of the weight of the boat (hence their use on ORMA tris). They work by reducing the wetted surface of the leeward hull through changes in trim and draft, which reduces viscous resistance.

Boats with a lower side load for their weight may see no advantage from canted boards. A-cats are narrow for their hull length and carry a rig with a high center of effort - so might not be good candidates for canted boards. A wide cat with sail area not limited by a rule is more likely to benefit.

Canted Hulls:

Canted hulls allow the hull to be more upright in the water when the boat is heeled. This results in a slight reduction in wetted surface - which helps reduce viscous drag.

If the hull has slight bow tumblehome or vertical sides the sheet of water on the hull (feather) can remain supercritical (WRT shallow water waves in the spray sheet) for a longer distance from the bow when the hull is not heeled. This reduces the spray drag since the hydraulic jump occurs on a portion of the hull skin that is inclined less forward. Spray drag is not so important for ships, but it matters for small high speed craft.

If the centerboard is kept vertical it's lift to drag ratio will be highest. At lower speed, and for boats that do not have a very high side load for their weight vertical boards are more efficient.

-colin pitts