In article , "iwdplz" wrote:
"harry k" wrote in message
For 27' feet? You won't even be close at the end.

If he uses the chalk line to make sure he's parallel with ALL of the dashed
lines, including lines near the end which are vertically aligned using the
top of the panel as a measuring reference, why wouldn't it be close at the
end?

Any small error in marking is magnified as the number of marks increases. So
is any small error in the level itself.

A water level is dirt cheap to make and dirt simple to use, and its accuracy
rivals that of professional surveying equipment. Why use anything else?