How to find true North (not magnetic North) in Hamilton?

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5 years 7 months ago #527826 by fungus
In the process of building a house in Hamilton soon but we want the house to be true North facing.
-Did a bit of google and found there is some sort of formula / declination based on your location and add or subtract that to your West or East and etc... ..way over my head.
-Downloaded a finding true North android app on my phone.....but it doesn't work.

Been told there is a basic way of finding the true North base on putting a stick on a land and looking its shadow at noon but then I got told by another person is 1pm due to daylight saving or something?!

Can someone clarify the last method for me?

Thanks

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5 years 7 months ago #527831 by Rokker
The National Oceanic and Atmospheric Administration (NOAA) has calculators that you can use to calculate the magnetic deviation at different points on the earth.

For Hamilton we get the following data:

Date: 2016-11-22
Latitude: 37° 46' 34" S
Longitude: 175° 16' 23" E
Elevation: 0.0 km GPS
Model Used: WMM2015
Declination: 20° 17' E changing by
0° 3' E per year
Uncertainty: 0° 20'

So the direction of true north is 20 degrees, 17 minutes East of magnetic north as of today, but going further east by 3 minutes each year.

Do NOT cross this paddock! ... Unless you can do it in 9 seconds, 'cos the bull can do it in 10!

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5 years 7 months ago #527834 by Stikkibeek
It's also pretty easy to find true north if you have a. a sunny day, and b. an accurate analogue watch.

If you need to create a shadow to help line the watch up, then, a pencil is ideal, or a stick in the ground. Line up the watch so the shadow falls through 12 and 6. Then, bisect the gap between the 12 and the hour hand and that is north. If you are on daylight saving (As at present), then use the 1 and 7 for your shadow line and bisect the gap between the 1 and the hour hand.

It is best to take off the watch and put it flat on your hand, or the ground or any other level surface.


If you are in the northern Hemisphere, you use the hour hand to line up with the sun, and the bisect between the hour and 12, is south.

Did you know, that what you thought I said, was not what I meant :S

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5 years 7 months ago - 5 years 7 months ago #527845 by Rokker
Yep, that's exactly how we used to do it on bush tramps. Stand facing the sun (shadow directly behind) and holding your watch with the 12 straight out in front (or the 1 for daylight saving), then true north is at an angle half way between the 12 (or 1) and the hour hand. It's reasonably accurate - only limited by how good you are at standing still and sighting up the angles. Stikki's method of using a stick would make it a lot easier I'd imagine.

Do NOT cross this paddock! ... Unless you can do it in 9 seconds, 'cos the bull can do it in 10!
Last edit: 5 years 7 months ago by Rokker.

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5 years 7 months ago #527849 by Hawkspur
Anywhere within 10 degrees of True North will be close enough. That applies to sun, shading and solar panels, so don't get too worried about precision.

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5 years 7 months ago #527855 by igor
When using the watch or clock method always remember to correct for daylight saving time.

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5 years 7 months ago #527862 by Rokker
To get really technically pedantic, a magnetic compass needle actually points to the earth's magnetic south pole, not magnetic north. The earth's magnetic north pole is actually just off the Antarctic continent near the Ross Sea. The North magnetic pole is more accurately known as the North-seeking magnetic pole. Here endeth the Geophysics lesson for today! :S

Do NOT cross this paddock! ... Unless you can do it in 9 seconds, 'cos the bull can do it in 10!

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5 years 7 months ago #527866 by muri
there are aps you can downlopad and you can find out the shading of sun on a building called Sunseeker
There is another with a similar name, one is free for downloading so perhaps search what aps you can obtain

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5 years 7 months ago #527873 by spark
NIWA Solarview might also be useful:
www.niwa.co.nz/our-services/online-services/solarview
solarview.niwa.co.nz/
(free to use but you have to register)

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5 years 7 months ago #527911 by Aquila
In the late afternoon or early morning (because the shadows are longer) put a stick in the ground. Put a second stick on the end of the shadow. Wait an hour. Put a third stick on the end of the shadow. Pull the initial stick out of the ground. Draw a line between the two sticks, this is East West. Draw a line crossing the line at right angles, this is North South (North is towards the sun in the southern hemisphere)

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5 years 7 months ago #527920 by Mudlerk
Aquila, that IS clever! Put a tail on it and call it a weasel!!

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5 years 7 months ago - 5 years 7 months ago #528002 by Aquila

Mudlerk wrote: Aquila, that IS clever! Put a tail on it and call it a weasel!!

Cheers, can navigate by the stars too. 13 years in search and rescue, you learn a few things. No technology, no apps, no registering and completely forget about magnetic North.
Last edit: 5 years 7 months ago by Aquila.

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5 years 7 months ago #528003 by Rokker
Yep, there you go, fungust - locate South by using the Southern Cross, and obviously North is directly opposite direction.

Imagine a line from the head to tail points of the cross, go about four and a half times that distance further from the tail point, then drop a line down to the horizon from there. That gives you true South.

Do NOT cross this paddock! ... Unless you can do it in 9 seconds, 'cos the bull can do it in 10!

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5 years 7 months ago #528018 by fungus
THANKS for ALL the replies!!! Very helpful!

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