more simmions questions

I think Ive got the bottom and rocker info down but what about the deck and rails? does it have to have an s deck ive seen alot with out it but ive also seen some with a scooped out nose. How much volume are you guys leaving in the rails is it more of a flat deck  and the thickness is carried out to the rails? Or is it more of a domed deck with pinched rails.

Thanks guys