Why are Nacra dagger boards tapered forward at the top?

Hi,

Does anyone know why the Nacra (5.2 and 5.8 generation etc) dagger boards slope in at the top? e.g.:

http://www.bnrwatersport.com/images/stories/virtuemart/product/IMG_0118.jpg

Sometime I find when I pull them up from being all the way down they jam a little if not pulled up straight, I might need to put a bit more carpet in a key spot but if they didn't taper at the top then they would only be able to come up straight?

Anthony
To save weight?
Reduced windage. Later boards cut a large handle hole as well. In higher winds you wouldn't be running the boards all the way down and having a foot of board sticking up above each hull hurts performance. The slope also helps your body slide off the top of the board if you fly into it during a pitch pole.