If you look at the AC boats the curved boards are forward of the front cross bar. This would make sense since the purpose is to just keep the bows up. I wonder if the placement of the boards is to far aft. The placement works for a balanced sailplane. But the further aft the boards the more the nose comes up in porportion to the lift the boards create. They may need to move the boards or reduce the amount of curve thus reducing the amount of lift.