Magnetic Compass

[tomtinker]

Why does my compass always point south ?

It is because the other end always points North.

 

[dcarp]

I Saw this tool up at hunting camp yesterday.
It's been there for years and I rarely give it any thought. It's nothing special but we still use it now and then.
We're real friendly with our neighbors up there but each side will occasionally "walk the line" and flag the trees with tape.
Best when you can do it with a couple of youngsters. Train them on a compass and throw in a little about Earth's magnetism while you're at it. Then have them run ahead and "hold the tree" we sighted on.
Not many kids around anymore tho. Maybe folks are forgetting to have them?
I looked on ebay and found a couple like this one.
Worth about $20.
They have some nicer ones there too.
$45 for a brass one. Same style and brand.
But I didn't bite on any.
Anyone here collect compasses?
I'm thinking there might be some who do. Maybe one that sits on its original binnacle and is valuable as heck....
Or you got one from your Grand dad that you like.
Or one that survived the wars?
Anyway...
Compasses are great tools and I don't remember seeing them talked about much here on Tool Talk
So let's see yours.
And No, the app on your phone doesn't count.
Thanks

There is one in the IPhone. Don’t have a clue about it’s accuracy

 

[unc]

There used to be a company that made compasses called the Tates Manufacturing Company. They weren't very accurate though, and some would say He who has a Tates is lost. unc

 

[Oregon Tractor Jack]

When I was traveling for business I would carry a compass. I would use it to navigate around in big cities. My anchor point was my hotel and I would take a bearing and walk around. It was a great help when you don't speak the language or the streets are not laid out in any type of reasonable grid. Take a look at the street map of London, UK for example...

OTJ

 

[Ozlander]

According to some recent news, the N pole has moved significantly over the past several decades. It makes me think I need to reset the declination on my Silva before I run another property line for the neighbors. It's a good thing we are going between established pins, but once in a while it takes a bunch of off-setting to get it to be a straight line between pins. There's always a lot of trees in the way, too. steve

And that is the reason airport runway numbers change every so often.

 

[stevieb49829]

There is one in the IPhone. Don’t have a clue about it’s accuracy

dcarp, the only way it could be very accurate, is if the phone knows your location, and it can use your location to adjust the declination, Check your permissions, to see if the compass app has permission to use your location.

Think about this: our declination here is about 22 degrees. That means the needle is pointing 22 degrees off of where true north is. And maps are based on true north. steve

 

[dcarp]

dcarp, the only way it could be very accurate, is if the phone knows your location, and it can use your location to adjust the declination, Check your permissions, to see if the compass app has permission to use your location.

Think about this: our declination here is about 22 degrees. That means the needle is pointing 22 degrees off of where true north is. And maps are based on true north. steve

Yup, here ya go.

 

[Charles in Aus.]

Maybe it's an Australian compass?

Unless it is a ' Global compensated compass ' , it won't work very well in Australia. Compasses for the Southern Hemisphere are weighted to allow for magnetic variations here .
I found this out while trekking in Europe , my compass from home was wildly inaccurate there .

 

[Charles in Aus.]

My WW1 British Expeditionary Force ( BEF ) compass with original leather case .

 

[john in la]

If you have a few hours and know how to use the sun with a stick (most of the instructions on the internet are wrong) you can find true north and set the declination of your hand held compass.

 

[stevieb49829]

Unless it is a ' Global compensated compass ' , it won't work very well in Australia. Compasses for the Southern Hemisphere are weighted to allow for magnetic variations here .
I found this out while trekking in Europe , my compass from home was wildly inaccurate there .

That's a really good point, Charles. I tend to forget this forum is world-wide. steve

 

[john in la]

A unweighted compass will point up and down unless you are on the equator.
A compass from the north is weighted on one end while a compass from the south is weighted on the other end so the needle stays flat.
If you use a compass from the south in the north the needle will point up and down and get stuck on the base to where it will not rotate freely.
A compass works best on the equator and the more you move off the equator the more you have to compensate for latitude.

 

[stevieb49829]

Unless it is a ' Global compensated compass ' , it won't work very well in Australia. Compasses for the Southern Hemisphere are weighted to allow for magnetic variations here .
I found this out while trekking in Europe , my compass from home was wildly inaccurate there .

I just started thinking about that. Are your compasses designed to be attracted by the south pole, since it is closer, and therefore more powerful of an attraction? steve

 

[john in la]

Steve
First remember if you put two like ends of a magnet together they will push apart and if you put two different ends of a magnet together they will pull together. A compass is a magnet on a stick.

A compass always points to magnetic north no matter where you are.
But if you remember back in school the magnetic lines come out the south pole fly over the earth and go in the north pole.
At least till our magnetic poles flip.
This causes the compass to point up and down toward or away from the center of the earth the closer you get to the poles.
So they use a small weight to keep the needle level.
In the south the weight is on one end of the needle to stop it from pointing up and in the north the weight is on the other end of the needle to stop it from pointing down or vise versa I can not remember.
On the equator a compass does not need a weight.

Your latitude will determine how much you have to compensate for true north from magnetic north.
This figure changes over time as magnetic north moves around.

Take a stick and put it in the ground before sun noon.
Mark where the shadow is.
Measure the shadow length and draw a circle around the stick.
As noon gets closer you will notice the shadow move and gets shorter.
After sun noon the shadow will get longer.
When the shadow gets the same length as when you started you will be at the same time after sun noon as you was before sun noon when you started.
Draw a line between these two points.
Draw a line 90 degrees from this line.
This second line will point to true north.
Take out your compass and see where it points.
Now you know how many degrees off your compass is for your latitude.
You can now use this degrees off to always find true north for your latitude.
Or you could just look it up on the net by your GPS spot and save yourself the time.

Most instructions on the net tell you to wait 15 to 30 minutes for this sun dial.
This does not compensate for the shadow getting shorter or longer so it makes your line off.

 

[stevieb49829]

Steve
First remember if you put two like ends of a magnet together they will push apart and if you put two different ends of a magnet together they will pull together. A compass is a magnet on a stick.

A compass always points to magnetic north no matter where you are.
But if you remember back in school the magnetic lines come out the south pole fly over the earth and go in the north pole.
At least till our magnetic poles flip.
This causes the compass to point up and down toward or away from the center of the earth the closer you get to the poles.
So they use a small weight to keep the needle level.
In the south the weight is on one end of the needle to stop it from pointing up and in the north the weight is on the other end of the needle to stop it from pointing down or vise versa I can not remember.
On the equator a compass does not need a weight.

Your latitude will determine how much you have to compensate for true north from magnetic north.
This figure changes over time as magnetic north moves around.

Take a stick and put it in the ground before sun noon.
Mark where the shadow is.
Measure the shadow length and draw a circle around the stick.
As noon gets closer you will notice the shadow move and gets shorter.
After sun noon the shadow will get longer.
When the shadow gets the same length as when you started you will be at the same time after sun noon as you was before sun noon when you started.
Draw a line between these two points.
Draw a line 90 degrees from this line.
This second line will point to true north.
Take out your compass and see where it points.
Now you know how many degrees off your compass is for your latitude.
You can now use this degrees off to always find true north for your latitude.
Or you could just look it up on the net by your GPS spot and save yourself the time.

Most instructions on the net tell you to wait 15 to 30 minutes for this sun dial.
This does not compensate for the shadow getting shorter or longer so it makes your line off.

Thanks John. I didn't understand the weight thing, but that makes sense. Now I know why one end of my compass needle is bigger/heavier. And all I do is look up one of the declination charts every once in a while to keep me and my compass honest. But I might try the stick trick one of these days with the grandkids, who are learning orienteering. steve

 

[Charles in Aus.]

I just started thinking about that. Are your compasses designed to be attracted by the south pole, since it is closer, and therefore more powerful of an attraction? steve

We are backwards and often upside down in many things , our compasses though , still point to North .
An old rhyme I was taught as a boy , no need for a compass if your watch is accurate.
" Point the hour of the day to the sun in the sky , twixt this and twelve doth true North lie ".

 

[Hemmjo]

Why does my compass always point south ?

If it always points South, you are at the North Pole!!! Watch out for those cuddly white bears!!! They are always hungry!!

 

[Hemmjo]

We are backwards and often upside down in many things , our compasses though , still point to North .
An old rhyme I was taught as a boy , no need for a compass if your watch is accurate.
" Point the hour of the day to the sun in the sky , twixt this and twelve doth true North lie ".

How many have an analog watch these days?

 

[Charles in Aus.]

How many have an analog watch these days?

A quick count numbered 15 in my desk drawer !
The question remains though ; " How many keep a compass in their pocket ?".

 

[Hemmjo]

I have an old compass that I got from an old guy at my church. We were helping him move to a new place. It is an a brown leather case. Stamped on the case is " G & K, 1918 CWA". From what I have read it is a WWI vintage gunnery compass.

The liquid inside is thick and the dial will not rotate freely. I have been tempted to take it apart to see if I can clean it up and get it working, but don't really need it and hae too many other projects