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Subject: Re: COMPASS ROSE
From: Dan Hogan (dhhogan@XXX.XXX)
Date: Sat Mar 24 2001 - 14:01:30 EST
On 24 Mar 2001, at 8:59, Edgar Kitchin wrote:
[Snip]
> Then there is the system that one no longer sees which had the form "N
> 45 E", "S 20 W" etc. for which I can't see any advantages but presumably
> they some at sometime.
>
[Snip]
The above system is the result of using "the Law of Cosines" formula for
sight reduction. HO 208 and many of the pre-WWII short tables give the
answer in reference to N/S__W/E of the quadrant. These required
memorizing a set of "rules" to use them.
Let L= latitude h= altitude
d= declination Z= azimuth
t= local hour angle
h= sin<-1> (cos L x cod d x cos t + sin x sin d)
Z= sin<-1> (cos d x sin t / cos h)
The above formulas can be worked with an pocket calculator or, if you
really want to work, with a set if Trig Tables. Most are described in pre-
1995 navigation manuals.
Dan Hogan WA6PBY
Catalina 27 "GACHA"
Navigation-L List Owner
dhhogan@XXX.XXX
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