NavList:

Guy:

While I studied for the USPS Navigator grade back when Ageton rather than NASR was the accepted "compact table" reduction method, I do not believe the use of an Assumed Position rather than a DR as the starting point for sight reduction should significantly affect the accuracy of a sight reduction.   The major items affecting the accuracy of a sight reduction (and remember, this is for calculating Hc and comparing it to Ho) is the accuracy of almanac data and the granularity of the tabular reduction data.  For a quick sanity check, consider what would happen if you were doing Law of Cosines with your DR position the same as the assumed L/Lo positions required by NASR.   Would you expect one to be more accurate than the other?

Lu Abel

Guy Schwartz wrote:

Hello folks:

I am studying for the Navigator grade in the US Power Squadron.

Part of my sight folder is a two object sight that need to be plotted using law of cosine and using the Nautical Almanac Sight Reduction methods.

The power squadron has a 3 mile tolerance (GPS location vs. fix position).

My concern is that the 3 mile tolerance is for both Law of cosine and NASR methods.

It seems to me the NASR would deserve a larger tolerance in that there are assumed L and Lo positions as starting points

Am I right?

Thank you,

Guy   

 

"May the SCHWARTZ BE WITH YOU"

 

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