graham
New member
For my sins I seem to spend quite a lot of time playing with other people's survey data as well as my own.
Over the weekend I have been having an interesting exchange about compass errors. We found a discrepancy between two surveys of the same cave, done thirty years apart, of up to 14 degrees. Now, it is probable that 4 degrees of that is down to magnetic deviation, but that might possibly leave a compass error of ten degrees.
This was no surprise to me, as much of the data I have used has had anything up to 12 degrees of correction needed, though much of that was Mag Dev, in Ireland where it's bigger than round here, but was found to be alarming by others.
So my question is: what sort of compass errors have people had to deal with?
Over the weekend I have been having an interesting exchange about compass errors. We found a discrepancy between two surveys of the same cave, done thirty years apart, of up to 14 degrees. Now, it is probable that 4 degrees of that is down to magnetic deviation, but that might possibly leave a compass error of ten degrees.
This was no surprise to me, as much of the data I have used has had anything up to 12 degrees of correction needed, though much of that was Mag Dev, in Ireland where it's bigger than round here, but was found to be alarming by others.
So my question is: what sort of compass errors have people had to deal with?