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accuracy

The difference between your true position and the fix position found from a round of celestial sights. Generally this is better thought of as the uncertainty in your fix, which, with good procedures and a good sextant, should be less than 3 or 4 miles routinely. This can be improved to about 0.5 miles, but this requires special care, especially when moving. Anything over about 10 miles indicates some problem with procedures or equipment. A rough way to judge your accuracy is the size of the triangle of crossed lines of position, assuming that each side of the triangle represents the average of several sights of the same body. The most accurate fix comes from sights of 3 bodies, bearing about 120° apart. See Sextant Sights and Fix.

Accuracy in dead reckoning is the difference between your fix position and your DR position at the time of the fix. With calibrated instruments and careful dead reckoning this should be no worse than about 15 percent of the distance run since the last fix, although this depends very much on the conditions present. See Dead Reckoning.


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