What people fail to see here is that you need a single number, history had told us this over and over again, any rule that tries to have a rating for different conditions runs into trouble very fast. IRC rates Supermaxi's to 1/4 tonners very well and this has a single number system (it's not perfect but what system is?), IMS had many rating for different conditions and it's just about dead! Is SCHRS only in Europe?