The Inter 17s (among others) use canted hulls so that the leeward hull and board and rudder are perpendicular to the water when the windward hull is flying just above the water (the ideal configuration). This positions the hulls for lowest wetted surface (lowest drag) and the lifting foils for their best performance in resisting leeway.

Higher aspect ratio foils are more efficient than lower aspect ratio foils, in general. Aspect ratio is length over width of the segment that is under water in design position, in this application (I think).

I hope this helps.