Compass Question

S

STAGE 2

Joined
Oct 11, 2005
Messages
1,178
What is the point of having tritium markers on the bezel and base of the compass if there aren't any on the needle?

I saw one in the store today that had this and couldn't for the life of me figure it out.
 
Proly a cheapo compass.

They more than likely aren't tritium either but glow paint.

there is no reason not to have the needle glow, it should have the paint like the rest of it.

Skam
 
STAGE 2 said:
Actually it was a $55 silva compass. I can't remember the model but it looked nice.
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It is not unknown for compasses to be defective. I have seen a few that pointed south instead of north. Also I saw one that was designed for surveying (I think) that only had 0-90 degress marked on the bezel. Make sure you don't buy the wrong one and that it works correctly.
 
I always give them a run through before I buy. I just thought it was really wierd. If it was a defect, then it was the whole batch because each one on the rack was like that.
 
STAGE 2 said:
Actually it was a $55 silva compass. I can't remember the model but it looked nice.
Click to expand...

Odds are you didn't notice the paint on the needle or they have made an error. Cant see Silva doing this knowingly.

Skam
 
Codger_64 said:
Hmm... the Australian model?

Codger :D
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I had forgotten about this thread so I had to look and see if the gent got his question answered/resolved. I saw your post and had a good chuckle. You would be suprised how many people actully think that. But seriously folks it does happen.
Codger, you probelly know the difference but I wonder how many people know the differance between compasses built for the southern hemisphere and the one built for us northerners.
 
Yes, it was tongue in cheek. Probably very few know the differences (or care) between compasses made for the N and S hemispheres. I doubt that most know about the "error" in compasses and maps or how to compensate for them either. There are some excellent tutorials online for compass use though if anyone is interested. For the deviation between true North and magnetic North for your particular location in the U.S., look at the corner of the USGS topo map for your area. It will show the angle of declination.

In this example from topozone, pick the "whats this" text below the trail topo map for a window explaining the above.

http://www.topozone.com/map.asp?lon=-93.1058&lat=35.7314&datum=nad27

Codger
 
The N/S hemisphere thing does create problems if you take a compass north or south that was designed for the other part of the world.

I'll try to explain it...

The magnetic lines of force flow north and south in a curve that roughly follows the curvature of the earth. The compass needle will align itself to this vertical force as well as the horizontal. A compass made for the Northern hemisphere is weighted to spin freely in the northern hemisphere taking this vertical alignment into account. If the same compass is taken...to Brazil for example... it will align itself at such a sharp angle that the compass needle will press up against the glass so hard that it won't rotate freely.

With some compasses this is very pronounced and others it is barely noticable. You can get the compass needle to spin freely by tipping the the body of the compass but it is a pain and can affect getting an accurate read. My Recta DP-2 works here and in PA so I am happy. The first time I went home from Brazil I took a baggie of compasses home and left them with my brother. Mac
 
Anybody try a Suunto Global compass? I always wanted one, but I doubt I am ever leaving North america
 
Personally I prefer the higher-contrast colors on the non-global Suunto compass' needle. If you're not leaving NA, then save your pennies for the next toy, er, peice of much-needed gear.
 
It could be that there was tritium underneath too. When it glows and the needle is dark, you can tell where it is pointing.

Kind of like the Cammenga compasses. They have phosphorus or tritium on the N arrow, but also a big blob in the bottom of the compass. When it glows you can still read all the numbers on th dial, besides being able to see the N arrow.
 
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