A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Greg Rudzinski
Date: 2014 Jun 30, 10:06 -0700
Doniol longhand sight reduction summary.
1. Simple rules.
2. Easy to memorize.
3. Uses DR as assumed position.
4. Fast four place precision.
5. Flexible for longhand, log, slide rule, or basic non trig calculator.
6. Works with as few as 2 pages of cosine sine tables.*
7. Reduction fits on one side of an index card with room to spare.
8. No form needed.
1. A few subtraction steps.
2. Azimuth is not reduced. **
* A 6 page haversine table is recommended to save time and reduce errors.
** The classic azimuth formula using diagram , slide rule, or longhand to 2 places complements the Doniol Hc formula.
The pros far out weigh the cons making Doniol a leading contender to replace the clumsy NASR at the back of the Nautical Almanac.