Hi, I'm trying to calculate the maximum bending stress in a beam with a varying cross section. I found a great resource (link below) that gives examples on how to do this but am a little confused. Basically the equation used is σ=M/Sx I know what σ and M are, but I haven't a clue what Sx is meant to be. Can anyone tell me what this is? It's kind of tough to figure our a way to google "S" and get meaningful results. Thanks! http://www.aaronklapheck.com/Downloads/Engr112_Handouts/ENGR112 Solutions/05-03ChapGere.pdf PS. What I'm trying to do, is calculate the maximum stress of a boat hull. I'm approximating it as a beam, but the cross section geometry is arbitrary. If any one has any suggestions about a better way to do this, they are certainly welcome!