Once upon a time I was surfing on swaylocks until the end of the night and I remembered reading someone explained how to calculate rail rocker with stringer rocker and concave measures. It was looking super obvious to me at this time until today where I tried to find out how to do it. After making sketchs of rail and stringer and board and aluminium bar and ruler and etc etc I find myself really confused. So I tried to find the post I've read few weeks ago and I can't. Did I really read it? Can someone help me please?