I'm new to this field, working on my first calibration and course certification. I've had my head in the manual enough to make my eyes hurt, but I do love the detail and procedural aspect of it all.

In Appendix F of the 2022.1.1 manual, it states that "The marathon is defined as 42.195km exactly". It shows conversions for the half marathon and the SAE equivalent distances - 13.10938M in my case.

My confusion is that the online system goes as far as to need the temperature of my steel tape, but yet does not allow me to use the fifth decimal place to enter the distance for my half marathon course application. I would think that the five inches that the 0.00008 miles represents is probably more than a tape would stretch on a hot day.

My main worry however is that the system is going to complain that my distance counts (13.10938M) don't match the applied-for distance (13.1093M).

Am I over thinking this? I am about to hit the submit button on my first certification and would very much like to get it right.

Thanks,

Tom

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Original Post

Tom, first, welcome to course measurement!!

It never hurts to take a step away from your data from a few hours or even overnight when things don't add up.

To your question (I may start and argument with my suggestion) but this issue would  a moot point if the course is measured metric, as 42.195km with a KM constant. Marathon and Half should be measured metric, then you wouldn't need to do this conversion and the decimal places wouldn't be an issue.

The only courses I measure with an imperial constant is an imperial course, 1-mile, 10-mile etc.

respectfully,
Brandon Wilson
Regional Certifier, South Carolina

I couldn't agree with Brandon more. The length of almost all races is defined in kilometers, including the marathon and half marathon. You'll save yourself a lot of headaches in dealing with seemingly random decimals if you do your final course length calculations in metric rather than imperial.

Those are great points. I should have thought of that initially. The calibration course that we did was for 1000' and is still pending certification. I think I'll make another for metric, as we're going to certify a gravel 50k course in the coming months. Would you go with a 300m course?

When I first started measuring, Jay Wight strongly suggested that I do all my calculations using metric and it made my life a lot easier. Now if I could just figure out how to abandon ounces and tablespoon measurement when cooking.

Your 1000ft cal course is 304.8 meters long. There is no need to measure another cal course. Is 300 really that much easier to type into your calculator or spreadsheet than 304.8?

For several years I have made my calibration courses by picking the endpoints and then measuring the distance between them. Examples of endpoints might be the south edge of a sewer drain or the first road expansion joint south of the driveway of a house address. Using endpoints like that make them easy to identify if the nails disappear. And around here pretty much all nails disappear every winter due to snowplows. An arbitrary distance for a cal course, as long as it is greater than 300m, is fine. And I would argue that it's better than an arbitrary endpoint.

To expand on Mark's comment, you already know your cal course is 304.8m, here is how you calibrate in metric (and this formula will work for any metric cal course):

Calibrate on any METRIC cal course using this formula:
(1000 / cal course length in meters * Avg counts) * 1.001
(we're going to assume your avg counts were 3434)

(1000 / 304.8 * 3434) * 1.001 = 11277.6706 ct/km

Convert to miles to layout mile splits
( 11277.6706 * 1.609344 = 18149.6515 ct/mi )

Basically if you learn those formulas you can calibrate on any course easily

And in-case you run into an odd distance imperial cal course:

Calibrate on any IMPERIAL course using this formula:
(5280 / cal course length in Ft * Avg counts) * 1.001

(5280 / 1000 * 3434) * 1.001 = 18149.6515 ct/mi

Convert imperial constant to metric
( 18149.6515 / 1.609344 = 11277.6706 ct/km )

It's pretty easy to memorize what you need to know.

Miles to km: 1.609344

feet to meters: 0.3048

5k = 3 miles + 172 meters

Half Marathon = 13 miles + 176 meters

Yes.

Bob Thurston has these conversions permanently stored in the calculator he uses for certifications. I need to do this.