I’ve been drawing out bottom roll and rail profiles on graph paper trying to get an idea of what I want with my next board, and I’ve come realize that your rail profile will always determine your depth of the roll. This seems obvious to me now, but a 3" board with bottom roll, and 50/50 rails will always have 1 1/2 roll. This all goes off the presumption that everyone is measuring roll depth at the apex of the belly to the apex of the rail.
How the roll progresses to the final depth is what I think counts. Knowing what rail profile you want and finding the curve that gets you to that point is what I think people are talking about when they say a board has so and so roll. The ol’ Swaylock’s saying rings true, “Don’t look at numbers look at curves”. Slight, medium, or deep belly is more about the curve between the points, and thus far measuring these as radius curves seems more reliable to me at this point.
I’ve got a board 3 1/4 thick with 1 1/2 belly (measured from belly apex to rail apex). Rail profile looked to be 50/50, but based off this they are 60/40ish.
How are other’s measuring bottom belly/convex?
Start talking about them bellies gentlemen!