In Nick Mordin's book, Mordin On Time, Nick writes "the average hurdle adds 0.7 of a second to the time of a race". Stating National Hunt Flat Races are usually 5.6 seconds faster than two mile hurdle race with 8 hurdles. Is this a good way of estimating how much a hurdle would slow down a horse, in your opinion? I've done some rough tests on this and I seem to be coming up with a hurdle taking a lot less time than 0.7 of a second. Somewhere between 0.2 and 0.3 was what I found. I'd be interested to hear if anyone else has a view on this.