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I was talking briefly with a pilot who is in a new government program to teach the old way of navigation with a sextant. They are during this in the event of a terrorist act to our systems. What was intersting is he said that 30 miles off course was acceptable. Were sexants that bad on accuracy? Waas GPS accuracy is 3 feet.

In it's pure math, the sextant can be very accurate. The two biggest limitations are the accuracy of your clock, and your ability to accuratly measure the height of the celestial body above the horizon. I would think for quick casual observations 30 miles is pretty good. It's really an offshore device of no use near land. I have a cheap plastic one I play with, but around here it can be tough to find enough open water to have a horizon to shoot at.

I was a navigator in the Navy and went to a 2 week school on celestial navigation. We used to play with sextants a lot at sea to keep up on it. The math calculations involved are extensive and easy to forget. The best fix I ever took was off by only a mile. 10 miles was average, but we were being competitive about it. My first few tries were off by close to 100. Good thing we had GPS as a backup:)

For those who are landlocked, like me in the suburbs, when I have a chance to play with my sextant, you can use a bowl of water about 15 feet away as an artificial horizon and get good readings.

I have one of those plastic sextants that included the instructions for the artificial horizon.

The plastic is nowhere near as accurate as an old sextant someone gave me. All the tools and fittings included in a wooden box.