Hollow in rear 1/3 of board = DACA profile. NACA don't have that.

I understand what you mean. I like the DACA profiles alot better. Board don't stall easily and you really turn them and pull the boat around without much fear of stalling them. It feels like the grip (bite) the water much better. That is unless the cord on them is too small. I think the I-20's suffered from that last issue before they went to the newer and larger cord rudder boards.

Wouter