G'day,
No centreboard. Just 2 oversize rudders in daggerboard cases hung off the side of the boat. A fixed centreboard makes shunting too slow and adds weight and cost as you still need 2 rudders. Two foils are all that is needed, and if they both rotate, they work much better. Can even angle them both slightly to force the boat to windward. Experience so far is that this is very costly in terms of speed, but handy when jamming for a mark, or stopping someone going past to windward.
Regards,
Rob