Hi John,

Sorry I didn't get back to you sooner; I have been kind of busy with the holidays.

> Well, I do have a question about the Tape Correction field

> in the survey editor, as I just had an opportunity to use it

> this week; we broke our tape(at the 0.4 foot mark) on the

> first shot of a survey. We recorded the distance data in the

> book as we read it- i.e., we didn't correct for the missing

> bit of tape.

[...]

> This may be a math word problem I just can't grasp, but as I

> see it, if I measure my height with an unbroken tape, I'd be

> 6.0 feet tall. If the tape broke at the 1.0 foot mark, I'd

> read the tape as 7.0 feet. I would want the correction

> factor to be subtracted from the 7.0 foot reading, not

> added, yes?

You are correct. The documentation isn't worded very well and actually I didn't really think it through very carefully when I wrote it. When I wrote the documentation, I was having a hard time imagining how someone would use the correction. At first, I thought maybe it would be used to correct for stretching of the tape, in which case, you would probably want the correction to be some kind of percentage. Somebody convinced me that tapes do get damaged and cut short and so I used the current system. You experience proves that the feature was worth including.

So, in your situation, you should use a negative correction factor. I have changed the documentation to read:

     COMPASS has three correction factors: Compass

     Correction, Inclinometer Correction and Tape

     Correction. These values are entered into the Survey

     Header and they affect all the shots in a particular

     survey. These values are added to the azimuth,

     inclination and length values for each shot. This

     compensates for any problems with the instruments. For

     example, if your tape was one foot short, you would

     measure each shot one foot longer than it really was.

     As a result, you would set the Tape Correction to minus

     one foot. This would subtract one foot from the length,

     thereby compensating for the defective tape.

The new help files will go up on the internet with the next release.

Larry