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Re: Magnetic Variation (Declination) Calculator
From: Greg Rudzinski
Date: 2009 Aug 4, 18:47 -0700

```Irv,

At the magnetic pole the needle does point down rendering the magnetic
compass useless. That leaves you with a gyro that seeks the geographic
pole. The seeking process is not that stable but is better than a
compass needle pointing straight down. At the geographic pole the
magnetic needle will be pointing down but not straight down where as
the gyro compass is trying to rotate 360� each day constantly seeking
north back and forth. Your 180� variation is true the same way that a
clock is correct twice a day. Steering by the Sun or stars is good but
what if you are in that zone of early twilight. Polar navigation is
problematic.

Greg

On Aug 4, 6:09�pm, "Irv Haworth"  wrote:
> What am I missing? When one is in the magnetic pole area �the "needle"
> points down (only is it horizontal at the equator)... To best of my
> knowledge gyro compasses do not function too well at either pole. �Lastly in
> these areas all directions are south..and let me add that the variation
> between the GP and Mag P must be 180�
> Now for another bevy ,in order to better meet the barrage..
> Himself aka Irv
>
> -----Original Message-----
> From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf
>
> Of Greg Rudzinski
> Sent: Tuesday, August 04, 2009 5:46 PM
> To: NavList
> Subject: [NavList 9354] Re: Magnetic Variation (Declination) Calculator
>
> �If a navigator walks around the magnetic pole(as apposed to the geographic
> pole) then it is the gyro compass that holds steady while
> declination/variation changes rapidly. Therefor when near the geographic
> pole use the magnetic compass to stay on track and when near the magnetic
> pole use the gyro compass to stay on track.
>
> On Aug 4, 4:36�pm, Greg Rudzinski  wrote:
> > Professor Manoj C. Nair of NOAA was kind enough to answer all my
> > questions by email and he explained to me that due to the convergence
> > of longitude at the geographic pole there will be large change in
> > declination(variation) as you walk around the pole with compass in
> > hand but the compass needle will be steady and unchanged as it seeks
> > the magnetic pole. A simple concept that I should have been aware of.
>
> > On Aug 4, 2:33�pm, Greg Rudzinski  wrote:
>
>
> > > Manoj C. Nair of NOAA University of Colorado responded to my email
> > > reguarding the zero result for 90� of latitude and said that the
> > > current program recognizes latitudes above 89.999 as undefined. The
> > > zero result must be a default number. I noticed another program
> > > glitch where 13� West declination was displayed as 167� East.
>
> > > Greg
>
> > > On Aug 4, 10:20�am, Brad Morris  wrote:
>
> > > > Hi Greg
>
> > > > I just entered the pole for a gee-wiz kind of exercise. �To my
> surprise, it returned zero, so I tried a location close to the pole. �That
> returned non-zero, indicating that the software has some sort of bug.
>
> > > > Since I have no way to verify any other result it may present to me, I
> will distrust the data. �How many other lat long locations give 'bad' data?
> �How would I know?
>
> > > > Should NOAA fix this? �Certainly. How silly of them to permit an entry
> which provides erroneous results.
>
> > > > Do navigators depend exclusively on a compass within 366 feet of the
> north pole? �I sure hope not...
>
> > > > Best Regards
>
> > > > -----Original Message-----
> > > > From: NavList@fer3.com [mailto:NavList@fer3.com]
> > > > On Behalf Of Greg Rudzinski
> > > > Sent: Tuesday, August 04, 2009 1:03 PM
> > > > To: NavList
> > > > Subject: [NavList 9329] Re: Magnetic Variation (Declination)
> > > > Calculator
>
>
> > > > It looks like values above 89.998996� of latitude are all zero
> > > > instead of 14� 24'W. Does NOAA need to correct this since it is
> > > > only 366 ft from the pole?
>
> > > > Greg
>
> > > > "Confidentiality and Privilege Notice The information transmitted
> > > > by this electronic mail (and any attachments) is being sent by or on
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```
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