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I cant see my reply to Stephen Collins SKID post. So I am repeating my post under a new topic

To see the comments added to a photo album click on the "comments" at the upper right of the post. (added by moderator)

That is a lot of weight to be handling! There is an alternative method which can be used for solo layout.

1. Hammer a nail in with just 4mm protruding and hook the tape over it:

In the picture I am showing the measurement of the end correction (this only has to be measured once)

2. Insert a nail at 50m with the tape NOT under tension. When you tension it will read about 49.990m

3. Having previously strapped up the tape drum with a loop you can hook the spring balance to, you can now tension the tape with your right hand while getting your head close enough to the nail to read the tensioned reading :-

4. Here is what you see taking the reading

The method is absolutely fool poof provided the nails are inserted far enough into firm tarmac so that they do not wobble at all under tension. Just remember to take along a portable masonry drill just in case you encounter a concrete road!
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I originally tried to use nails. It was 20 deg F out and I was having a helluva time trying to pound them in.

I was using concrete nails and even tried a hand (4 lb?)sledge hammer. They would bend, come flying back at me, go in crooked...

That's when I gave up and rigged up the skid.

My 330 foot tape has its zero mark offset from the end. That eliminates one more possible source of error.

In warm asphalt, it probably would have gone much better.
OK, I did a google search and found out what a P-K nail is. I figured McMaster-Carr would have every kind of hardware known to man, but aparently this is a surveyors' specialty item.

This should be explained in the Course Measurement Manual. I read it cover to cover and could make no sense of the nails aspect, so I just used concrete nails. Since you have to drive them in a couple of inches and they are skinnier, there is more potential for trouble.

Thanks for you kind words on my skid.
Neville read the tape correctly!

Any beginner wanting more details of laying out calibration courses will find a great deal of information elsewhere. The basics are well covered in the following two on-line references:

IAAF Booklet (.pdf)

USATF Course Measurement Manual

However these two don't deal with the solo method , which is the one I now teach all new measurers as the preferred method. The pictures, which I used to communicate the idea but not the detail in response to Stephen's posting of his photo-album, were actually taken from the on-line course measurement seminar. The seminar contains more details which may be of use to measurer undergoing training. You can read a bit more about the seminar in a posting I made here last year:

on-line measurement tutorial

I am afraid the only the introductory lesson can be readily accessed by all. You have to pass the introductory test and be given a password to again access to the full theory training seminar, which is supported by an on-line tutor. Although at present the seminar uses UK language, measurement forms, certification procedures, and assumes driving on the left(!), it could be internationalised if there is a demand.

P.S. ABOUT P-K Nails
It was Pete who first gave me a box of P-K Nails, years ago. I now give each new trainee a small bag of these, enough to layout his home calibration course. By the way the size, which I find generally useful, is 1 1/4 inch long and 3/16 inch diameter. However I do keep some slightly longer ones just in case I encounter very soft tarmac when the short ones might move under 10lbs side ways pull.
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