Could someone please set me straight on the definitions and differences between 60/40 rails and 50/50 rails (shape and performance differences). Also, can anyone tell me about "Pinched" rails? I've heard this term thrown around a bit lately...What exactly does this mean and how are they shaped? Am I correct in assuming this means the rail has an "edge" or a kind of "point" to it? I really like the rail shape of Hap Jacobs' H1 model, and someone told me that they're Pinched. But I still can't tell what that means. I'd like to try to shape my board with this rail style...How do I do it?