How to Backsight, The Art of Backsighting
by Walter Hargrave
who was taught by Mike Ryan and Mark Ronko

Disclaimer
In this article I will try to explain the art of backsighting poles in chain link & wood fencing as well as a simple comparison to using a string line. I personally only use a string for the top of wood fences that we are custom building on the job and not pre-fabed sections.

A string line is handy if you are alone to get the initial layout setup. If you have a team member, he can site my diggers in and we blaze down the line. Next we split one to mix the mud, while the other back sights the line poles in, ready for mud. :)

Why I like backsighting over string lines.

1. Back Sighting is Faster, you don't have to keep checking the string.
   
   
2. Wind is not a factor.
   
   I have seen jobs where 1 pole pushes the string out a bit which makes the entire line wrong if you don't catch it early and you have to go back and adjust it.
   
   
3. The string is not in the way of walking, buggy, or other moving entities. Note: We called the Wheel Borrow a "buggy".
   
   
4. Once you master it, you have lazer straight lines.
   
   
5. It's one more tool to wind up and let out over and over. Heck, while they are setting string lines, I am setting poles.
   

Backsighting

Basically you stand behind 2 already set and in line poles and compare by looking on each side, near the top, looking up and down the pole for how in line it looks compared against the other 2 line poles. You will be able to tell if one of the other poles is out of line or level here too. All the while holding the pole level in respect to line. You then check grade on the top setting it a bit high. If the hole is to deep, you can bring it up in the mud. Keep checking all three things.

Check level both ways, after you think you've got it, go back one pole and site it into the terminal on the other end to verify all is well. It usually is correct once you get the hang of it. Before you know it, you can do 3 or more and then check. If you can keep the poles level both ways and the grade across the top is perfect straight or rolling smoothly all without a string line, people are impressed by that.

More in a few.