A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Magnetic Variation (Declination) Calculator
From: Greg Rudzinski
Date: 2009 Aug 4, 18:47 -0700
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: > > > > Brad, > > > > 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 > > > > Brad > > > > > -----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 > > > > > Brad, > > > > > 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 > behalf of Tactronics; it is intended for the exclusive use of the addressee > named above and may constitute information that is privileged or > confidential or otherwise legally exempt from disclosure. If you are not the > addressee or an employee or agent responsible for delivering this message to > same, you are not authorized to retain, read, copy or disseminate this > electronic mail (or any attachments) or any part thereof. If you have > received this electronic mail (and any attachments) in error, please call us > immediately and send written confirmation that same has been deleted from > your system. Thank you." --~--~---------~--~----~------------~-------~--~----~ NavList message boards: www.fer3.com/arc Or post by email to: NavList@fer3.com To unsubscribe, email NavListemail@example.com -~----------~----~----~----~------~----~------~--~---