Over the years I've picked up a few good 'rules of thumb' and alternative measuring 'devices' that have proved to be useful tools for the toolbox in my head.
1. One minute of arc subtends about 3cm in 100m
2. Combined scale factor changes approximately 5ppm for every 30m change in height (5mm per 1000m distance)
3. Curvature of the earth is about 1/2 foot in a mile
4. My left index finger is 3" long
5. My left thumb nail is 1/2" wide at the base
Although the last two only work for me, I am certain there are others that my fellow surveyors have learned over the years. Any others that can be suggested?
6) When you get in the truck and ready to leave the job and get the sensation from your sixth sense that something is amiss - something IS amiss - so just get out of the truck and walk around until you figure it out.
7) The contrary will likely be shown by somebody at some unknown future time, if you don't follow rule #6
8) A SUV will be parked between two traverse points.
9)Quick steel tape correction (if anybody remembers those) is 0.01' for every 15 degrees (F).
:)Sometimes, it might make a little difference, but it doesn't really matter.
Amen, Wayne. Pay attention to that little voice - it is your subconscious trying to tell you something.
10) My boot is 12".
15lbs pull.....:)
If you stretch out your arm straight and extend your fingers wide, with your thumb up, and set your little finger on the horizon your thumb will be about 15 degrees elevation as a quick check for GPS visibility at your location.
You also look like a scarecrow!
This one comes in handy for me sometimes. 1 second of arc is roughly 0.01' at a radius of 2000'.
Only if you try to do it with both hands at once. 😉
If you can see a far horizon, it's level between there and your eyes.
It's 3' from my nose to the tip of my thumb (hand in a fist) with my arm extended horizontal.
It is exactly 0.10' between my top two knuckles on my left index finger.
A 3' boot with a rod is at the waist of my Levis.
The radius of a 1 degree curve is 5729.5779'.
A chord length is twice the radius times the sine of the deflection.
Don't ever do up the chain left handed.
Don't ever put 6H in your Pentel.
You can't get a sausage biscuit after 10:30 AM.
The span of my hand, from thumb tip to pinkie tip is 8-in
Every 3 fingers from the Horizon to the sun is approx 15 minutes of daylight left.
Pointer, middle and ring
When setting out on a surveying road trip I find that I am much less likely to forget something if I use a checklist (which I developed over time).
It takes 10 days for a thornapple thorn to fester and pop out on it's own- unless you're allergic...
People who espouse metrication should be institutionalized for their own safety....
the radius point is your friend.
be nice to the eits - someday they may be your boss.
one degree of arc at 100' is 1.745 feet.
Paden
Don't try to let out tape that was done up left handed. I did that ONCE, worst birds nest you have ever seen.
Andy
The from the tip of my pointer finger to my first knuckle is 0.1'.
good tips.
I remember when I was an "instrument man" I knew a lot of measurements for scale. I knew a range pole was 0.09' wide, the top of a plumb-bob tip was 0.03'. (the top of the plumb-bob was 0.04' and the edge of a gammon reel-I forgot). I knew a lot more, so if I told the rod-man 0.04 left I knew I was real close to correct. It was kind of irritating when rhe rodman would move a tenth when you told him 2-hundredths. Especially when the "rod-man" was your crew chief and blamed you when you had to tell them to go 0.08 back the other way.
