UKC

I am trying to calibrate the compass on a Casio Protrek watch that Mrs Nonymouse has just treated me to.

Does anyone know how I can get an accurate reading (+/- one/two degree) with which to calibrate it. I only have a basic Silva compass. Would a GPS be more accurate?

In reply to nonymouse: what are you trying to calibrate to? magnetic north or grid north?

In reply to nonymouse:

I'd expect the Silva to point pretty accurately to magnetic north, and you should be able to read it to within a degree or two

The GPS compass only works when you move, by (simplified) calculating the direction it has travelled (form at least one position to another) and then relating that to north. Since each position measurement is subject to an error, this will propagate into an error in the compass reading. Over time and distance this is probably tolerable, but I wouldn't think as accurate as a compass

In reply to woolsack: Sorry - Magnetic

In reply to nonymouse:

I wouldn't say so due to the perpetual need for calibration. The obvious would be another compass that you know works, a mate's?

In reply to nonymouse:

If its anything like the sunnto you just need to turn the watch 360 deg as the watch has inbuilt memory of where North is. Its a bit like a gyroscopic compass in an aircraft, movement expecially acceleration and deceleration/ g force allow it to drift. You then have to free the compass and slave (fix it) back onto mag north.

You shouldn't need to marry it up with a silva type compass, which are only accurate to +- 5 degrees and are affected by magnetic variation on the earth surface.