Awesome Rob, this was a long time coming, and im glad it came through you, if anyone reads this reply, be assured that you are getting a compilation of formulas from one of the best tutors/instructors in the business of Drilling (Rob St Ledger), by far the best i have been to while at my time with Transocean, if i ever get a chance i will always go to Robs IWCF school for my recertification and will always recommend him very highly.