I wish I had more knowledge than I do, mine has been one of measure every thing, get the compass degrees off of everything, I worked for a couple of years on 5 / 6 drill holes, had a good friend that showed me where they were at around a lake and could drive to them, different sizes, depth, finally got it figured out that the 4 inch wide ( 10 cm ) 4inch deep ( 10 cm )= 2 times the circumference ( 34.5 cm X 2 ) = 69 feet = a cordel = 189.5 feet, so started using that as a distance measurement and it worked out they did use compass degrees also except where they set the monuments to shoot across country. I wish I had some 18 year old legs to take me across country, I think I could live on fish, crawdads, rabbits, turtles. crubs, worms when I needed to.