Using the fat box what support the side of the board is that not important? I know the front and back load up but isn't there side loads on the boards? Does anybody know what brands of A-cats use these types of boards I'd like to check it out?
The boards, even on most typical beach cat with straight boards, are only supported by the deck opening and the hull bottom opening. The daggerboard trunks usually slip outside formed and sized openings for the daggerboard and don't normally provide any support for the board (some are even paper thin and pretty much there just keep the water out - like on the nacra 6.0).
The new (v5) Geltek Flyer and I think the latest EVO has the capability of running either straight or curved boards.
